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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Laughy on March 17, 2013, 07:06:40 PM
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Hello,
Wondered if anyone can help. I just dug out my old A500, checked it worked on a friend's compatible TV, it was fine. Took it home waited a couple of days, while trying to scrounge a TV off anybody I could!
Anyway, set it up, all good. Put one of the same disks in as I had checked it with, it failed to load! Got a little way then power light flashed. That's it!
Had a look on you tube for tips on cleaning disk drive, took Amiga apart, disk drive out. Couldn't get it completely out of casing, not having proper size tiny screwdriver, so cleaned as much of the fluff out of it, and the reading heads as I could with cotton buds and alcohol. Put it back, loads a bit more but not properly.
The other thing is I couldn't tune it in to the TV. Controller doesn't seem to be working, even with new batteries. I'm going to get an RGB to SCART cable as I have found out that TV is compatible.
Any help is much appreciated, as I don't know anything about fixing computers!
Thanks
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The power light flashing means the machine crashed. It probably has nothing to so with the floppy drive. To help you further, can you say whether it's a 500 or a 500+ , or if it comes up with a white or purple screen with no disk inserted. Also, what game(s) made it do this? trust me, it's all relevant.
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Hello,
Wondered if anyone can help. I just dug out my old A500, checked it worked on a friend's compatible TV, it was fine. Took it home waited a couple of days, while trying to scrounge a TV off anybody I could!
Anyway, set it up, all good. Put one of the same disks in as I had checked it with, it failed to load! Got a little way then power light flashed. That's it!
Had a look on you tube for tips on cleaning disk drive, took Amiga apart, disk drive out. Couldn't get it completely out of casing, not having proper size tiny screwdriver, so cleaned as much of the fluff out of it, and the reading heads as I could with cotton buds and alcohol. Put it back, loads a bit more but not properly.
The other thing is I couldn't tune it in to the TV. Controller doesn't seem to be working, even with new batteries. I'm going to get an RGB to SCART cable as I have found out that TV is compatible.
Any help is much appreciated, as I don't know anything about fixing computers!
Thanks
Hi,
A couple of things first! You need to count how many times the power light flashes, and is it consistent? Ie. happening at same point or various random times? Are you getting a picture at all, you mentioned your remote isnt working? At this stage it could be (off the top of my head) the PSU, floppy drive (some models have surface mounted caps that fail related to rotation speed), CIA or worst case RAM (not socketted, hard to remove).
Simple things you can do to start with are to remove RAM expansion and retest, take cover and shielding off and make sure all socketed chips are firmly in place. If its an a500+ you could have a leaked nicad battery, the same battery issue occurs in the 512Kb RAM expansions also.
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Hi,
A couple of things first! You need to count how many times the power light flashes, and is it consistent? Ie. happening at same point or various random times? Are you getting a picture at all, you mentioned your remote isnt working? At this stage it could be (off the top of my head) the PSU, floppy drive (some models have surface mounted caps that fail related to rotation speed), CIA or worst case RAM (not socketted, hard to remove).
Think he means the TV remote ;) also, he stated that it 'loads but not properly' so it seems like the machine kick-up ok. Think we're onto a compatability or dead disk issue.
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Think he means the TV remote ;) also, he stated that it 'loads but not properly' so it seems like the machine kick-up ok. Think we're onto a compatability or dead disk issue.
Yes, i thought he meant he'd not got it working with the TV because the remote isnt working? Why else mention the remote? Hopefully its the drive. He mentioned the game worked previously so it can't be the KS version, logically it's going to be the disk, the drive, loose chips, leaked battery, CIA, or RAM - I would check in that order. Btw, you can swap the 2 x CIA chips around to see if the behaviour changes - if it doesnt you can rule that out.
One of the most common chips i've seen fail in 500's and 2000's is the CIA, and it normally follows movement of the machine, static, and or removing devices whilst the a500 is on - design fault, something to do with different ground levels.
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Yes, i thought he meant he'd not got it working with the TV because the remote isnt working? Why else mention the remote? Hopefully its the drive. He mentioned the game worked previously so it can't be the KS version, logically it's going to be the disk, the drive, loose chips, leaked battery, CIA, or RAM - I would check in that order. Btw, you can swap the 2 x CIA chips around to see if the behaviour changes - if it doesnt you can rule that out.
One of the most common chips i've seen fail in 500's and 2000's is the CIA, and it normally follows movement of the machine, static, and or removing devices whilst the a500 is on - design fault, something to do with different ground levels.
+1 (including memory expansion)
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If there's a memory expansion in the trapdoor slot remove it and see if it changes anything. Usually, they've got a battery inside which leaks and eats up the board. If the fuzzy stuff has already spread to the board it'll need a good cleaning at best.
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Wow, Thank you all for your replies! I will try to answer all your questions!
Thankfully it's an A500 not the 500+! Have seen the damage caused to the motherboard from the leaking clock battery. When machine turned on, it does make the normal clicking noise from the empty drive, so I assumed it will have the screen with the hand and disk. No way yet to confirm this yet as I can't seem to find the signal from the amiga using the RF cable. It was fine on friends TV just days before I tried it at home.
I have tried everything I could think of on the controls on the TV itself (changing input on EXT, AV, VCR, etc) I was hoping that if I get the RGB to SCART cable I have seen recommended on this site, that the TV will recognise it, and I won't have to tune it. Works fine with a dvd player. Just thought there would be more options and ease of use with the TV remote.
I will go through all that you suggest and get back to you all.
Thanks again!
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The 500 doesn't output RF, it's only got (monochrome) composite and - much preferable - RGB. (Plus digital RGBI, but you wouldn't want that either.)
For RF you'll need an A520 modulator but as long as your TV has any way of directly inputting a video signal you won't really want that.
Try connecting the RCA jack on the left edge to your TV's AV input (any RCA cable will do). There's no color but you should be able to see something.
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The 500 doesn't output RF, it's only got (monochrome) composite and - much preferable - RGB. (Plus digital RGBI, but you wouldn't want that either.)
For RF you'll need an A520 modulator but as long as your TV has any way of directly inputting a video signal you won't really want that.
Try connecting the RCA jack on the left edge to your TV's AV input (any RCA cable will do). There's no color but you should be able to see something.
I've got the 520 Modulator, perhaps that has stopped working, as I put the RCA cable into the mono output on the Amiga, as you suggest and yes, I can see the usual screen with hand and disk! Fuzzy and not stable!
I tried the Workbench 1.3.2 disk, just to see what happenend, it did load a bit, but stopped..
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The power light flashing means the machine crashed. It probably has nothing to so with the floppy drive. To help you further, can you say whether it's a 500 or a 500+ , or if it comes up with a white or purple screen with no disk inserted. Also, what game(s) made it do this? trust me, it's all relevant.
On checking again it just crashes, power light just goes dim, no flashing. Though I could swear it did flash a couple of days ago (prior to taking apart and attempted cleaning).
It's a 500, with white screen. Games I played the other day which were fine, and not now : Turrican 2, Nitro and Project X.
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If there's a memory expansion in the trapdoor slot remove it and see if it changes anything. Usually, they've got a battery inside which leaks and eats up the board. If the fuzzy stuff has already spread to the board it'll need a good cleaning at best.
No battery on this trapdoor expansion, it looks absolutely clean, no damage. Have taken it out.
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Hi,
A couple of things first! You need to count how many times the power light flashes, and is it consistent? Ie. happening at same point or various random times? Are you getting a picture at all, you mentioned your remote isnt working? At this stage it could be (off the top of my head) the PSU, floppy drive (some models have surface mounted caps that fail related to rotation speed), CIA or worst case RAM (not socketted, hard to remove).
Simple things you can do to start with are to remove RAM expansion and retest, take cover and shielding off and make sure all socketed chips are firmly in place. If its an a500+ you could have a leaked nicad battery, the same battery issue occurs in the 512Kb RAM expansions also.
Socketed chips all firmly in place, the whole motherboard is in good condition. I can get the screen, followed suggestion from Zac67, without using the 520 Modulator.
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Socketed chips all firmly in place, the whole motherboard is in good condition. I can get the screen, followed suggestion from Zac67, without using the 520 Modulator.
Just to be clear, have you removed the modulator when using the black and white composite signal? maybe you plugged the modulator in whilst it was powered up or something? If video output is faulty it could be a problem with hybrid. Could be denise but unlikely I think. Try swapping the 2 x CIA chips around and check behaviour, if swapping them around changes behaviour it will be faulty CIA - i've got several spares.
Edit: when you swap them make sure they are installed the correct way around.
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Just to be clear, have you removed the modulator when using the black and white composite signal? maybe you plugged the modulator in whilst it was powered up or something? If video output is faulty it could be a problem with hybrid. Could be denise but unlikely I think. Try swapping the 2 x CIA chips around and check behaviour, if swapping them around changes behaviour it will be faulty CIA - i've got several spares.
Edit: when you swap them make sure they are installed the correct way around.
Modulator was unplugged when using the mono output. Just tried it again, get a picture both connected and unconnected. Just not through the modulator.
Had a go at removing the CIA chips, but they are well in and am a little worried that I will damage the chip and/or motherboard taking them out. I will have to get one of those PIL tools to grab both ends at the same time. It's going to take quite a bit of force in any case though.
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On checking again it just crashes, power light just goes dim, no flashing. Though I could swear it did flash a couple of days ago (prior to taking apart and attempted cleaning).
It's a 500, with white screen. Games I played the other day which were fine, and not now : Turrican 2, Nitro and Project X.
Modulator was unplugged when using the mono output. Just tried it again, get a picture both connected and unconnected. Just not through the modulator.
Had a go at removing the CIA chips, but they are well in and am a little worried that I will damage the chip and/or motherboard taking them out. I will have to get one of those PIL tools to grab both ends at the same time. It's going to take quite a bit of force in any case though.
The CIA will come out easily, just lever them out by putting a flat head screwdriver under the chip but above the socket and lever a little then swap to the other side. Repeat that proccess 4 or 5 times on each side until each side has raised out if the socket. Take your time and be careful and it should be easy.
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Do you have a multimeter? It's worth checking all the voltages are there from the PSU. Doesn't sound like a PSU issue but I am wondering if that modulator needs a 12v or -12v source or something, could explain the loading problems as well as the drive probably needs the 12v line also, whereas most if not all of the logic on the main part of the board will probably work with +5v line regardless of the +12v / -12v lines - they tend to be used for comms, and audio output.
EDIT: Regards my comment on the message previous to this one, see this video:-
https://www.youtube.com/watch?v=RkSCh53fO6Y
Around the 2:59 mark you can see how the guy remove the DIP chip from the socket. The smaller the blade on the screwdriver the better, he's used quite a large one there imo.
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Do you have a multimeter? It's worth checking all the voltages are there from the PSU. Doesn't sound like a PSU issue but I am wondering if that modulator needs a 12v or -12v source or something, could explain the loading problems as well as the drive probably needs the 12v line also, whereas most if not all of the logic on the main part of the board will probably work with +5v line regardless of the +12v / -12v lines - they tend to be used for comms, and audio output.
EDIT: Regards my comment on the message previous to this one, see this video:-
https://www.youtube.com/watch?v=RkSCh53fO6Y
Around the 2:59 mark you can see how the guy remove the DIP chip from the socket. The smaller the blade on the screwdriver the better, he's used quite a large one there imo.
I know I am quoting myself here but i've taken a look at the circuit diagram just now, and it could well be a PSU issue. +12v, +5v and -5v are used by the modulator. If you aren't getting a stable picture using the mono composite, it could be that your PSU output voltages aren't quite right.
EDIT: The Hybrid also takes in +12v, My suspicion is your +12v line is low (pray it isn't high or it may have damaged the Hybrid). You need to use a multimeter set to DC voltage and check the +5v, -5v, +12v.
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Do you have a multimeter? It's worth checking all the voltages are there from the PSU. Doesn't sound like a PSU issue but I am wondering if that modulator needs a 12v or -12v source or something, could explain the loading problems as well as the drive probably needs the 12v line also, whereas most if not all of the logic on the main part of the board will probably work with +5v line regardless of the +12v / -12v lines - they tend to be used for comms, and audio output.
EDIT: Regards my comment on the message previous to this one, see this video:-
https://www.youtube.com/watch?v=RkSCh53fO6Y
Around the 2:59 mark you can see how the guy remove the DIP chip from the socket. The smaller the blade on the screwdriver the better, he's used quite a large one there imo.
No multimeter, but could probably borrow one. You'll have to forgive my lack of knowledge of electronic stuff. I'll have another go with the CIA chips.
Just so I get it straight in my head, you think that it is one of the CIA chips that has stopped the drive from loading and stopped a signal going through the modulator?
Maybe I was a little misleading with my description of the mono picture, it is there, just not great, needs a bit of tuning. No flicker or anything like that. Sorry, shouldn't have said not stable.
I will have to look up PSU as I don't know what that is. I wouldn't know where I would have to test to find out the voltages. Shall I see if I can get a multimeter, and get back to you? I'm not sure what the hybrid is, sorry, I assumed you meant the RGB to SCART cable. I don't have one yet. But then, if the RGB output is buggered, no point getting one until I fix it?
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PSU = Power Supply Unit - the power brick
If you're using a multimeter, measure the voltages loaded, i.e. while the PSU is plugged in and the machine is running (or trying to). Just clip the black cord to ground somewhere (e.g. RF shielding), easy access to +5V & +12V is on the floppy power connector. DO NOT short circuit any power pins with their neighbors!
The "Vidiot" hybrid is that black card right next to the Denise chip (upper left corner). It's converting the digital video signals to analog ones for RGB output. Have never seen one die but you never know.
Apart from trying the very easy CIA swap my guess is on one the RAMs or the Agnus socket.
Is the floppy spinning up?
Is the head moving?
How long does it take from inserting the disk to the flashing LED? Anything on the screen then?
Have you tried removing the trapdoor expansion to see if it makes any difference?
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The pinout of the PSU can be found here:
http://www.hardwarebook.info/Amiga_500/600/1200_Power_Supply
And for a photo:
http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_Power_supplies/body_amiga_power_supplies.html
When using a multimeter, hold the common ground probe of the meter (usually black) to pin 2 - common ground. Then use the other lead (usually red) and hold on the voltage pins (1, 3 and 5) one at a time. You need both probes to touch one pin each to get a reading. Sorry for sounding too informative but I do not know how much electric/electronic skills you have.
Maybe that you can borrow a multimeter from can help you to check? Ask for help but stay with that person during the test and see what he/she does. And ask questions. Learn. And then get your own multimeter. For just checking basic voltages you do not need an advanced one. I paid ~AU$20 (~GBP14) for the one I have. And it's a decent one to to basic stuff.
Good luck!
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No multimeter, but could probably borrow one. You'll have to forgive my lack of knowledge of electronic stuff. I'll have another go with the CIA chips.
Just so I get it straight in my head, you think that it is one of the CIA chips that has stopped the drive from loading and stopped a signal going through the modulator?
Maybe I was a little misleading with my description of the mono picture, it is there, just not great, needs a bit of tuning. No flicker or anything like that. Sorry, shouldn't have said not stable.
I will have to look up PSU as I don't know what that is. I wouldn't know where I would have to test to find out the voltages. Shall I see if I can get a multimeter, and get back to you? I'm not sure what the hybrid is, sorry, I assumed you meant the RGB to SCART cable. I don't have one yet. But then, if the RGB output is buggered, no point getting one until I fix it?
Yes, the CIAs can cause all sorts of weird behavior as they connect to various other chips. I've seen for example CIA's cause the green screen error typically associated with bad RAM when it was the CIA, i've also seen CIA's interfere with floppy loading although you would expect it to be more likely to be the Gary chip or the floppy drive itself.
Swapping the CIA's is a nice easy check just to rule it out as they are identical chips and swapping them should result in no change in behaviour. If you get a significant change after swapping them around you know one of them needs replacement.
The other guys have given you some good advice there on checking the voltages - just borrow or buy a cheap multimeter, you will probably get one on ebay for £5 to £10 and the benefit is you can use it to check fuses around the house when things fail, or check voltages on batteries, test bulbs etc etc - everyone should learn to use one for those basic uses.
The hybrid as mentioned by one of the other chaps is the black ceramic package that is connected to the board at a slanted angle, just behind Denise and before the RGB socket. They seldom fail but they have rarely been known to fail, normally caused when connecting the modulator or monitor connection whilst the Amiga is powered up - but it is very rare tbh - i've accidentally wiggled the modulator around many many times and never damaged one. CIA's go for the same reason, disconnecting and connecting things whilst its on. I watched a great video recently by one of the head engineers from Commodore and he explained why that occurs - something to do with differing ground levels.
Start with the simple stuff, checking things are firmly in sockets, remove RAM expansion, check PSU voltages, try it without keyboard connected - does it boot and not crash then etc. Hopefully its something simple like the power supply, you could at least then get one off EBAY or something for £5 to £10 probably.
EDIT: When you want to check the voltages on that power connector, be careful not to short the pins on each other with the probes or you could damage the power supply.
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I watched a great video recently by one of the head engineers from Commodore and he explained why that occurs - something to do with differing ground levels.
Sorry for going a bit off topic here, but is this video available online? And if so, do you have a link? It sounds very interesting and I'd like to learn more:)
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Thanks all, suggestions taken on board. I will try swapping the CIA chips in daylight, I don't want to damage my computer! Have taken out RAM expansion. No change as yet.
Will also get hold of multimeter asap. As soon as have done chip swapping, will get back to you..
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Have swapped the CIA chips, that was a bit nerve wracking! Especially as one of them was really hard to get out. It all popped up in one go really quickly, and all the pins on one side were still in the socket, and got bent!!
Straightened them out, turned on. No picture through the modulator, so went back to the mono output. Get the white usual hand and disk screen. Tried loading a game, drive the same, makes two turns with the disk, then stops. Difference now seems to be that the power light doesn't dim!
There is something showing on the screen, it turns blue as the disk stops, and then, goes to what could be a white screen with something small being displayed. It is unstable at this point, diagonally flickering..
RAM is out too.
What should I try next? Getting the multimeter and checking power to RGB socket?
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Have swapped the CIA chips, that was a bit nerve wracking! Especially as one of them was really hard to get out. It all popped up in one go really quickly, and all the pins on one side were still in the socket, and got bent!!
Straightened them out, turned on. No picture through the modulator, so went back to the mono output. Get the white usual hand and disk screen. Tried loading a game, drive the same, makes two turns with the disk, then stops. Difference now seems to be that the power light doesn't dim!
There is something showing on the screen, it turns blue as the disk stops, and then, goes to what could be a white screen with something small being displayed. It is unstable at this point, diagonally flickering..
RAM is out too.
What should I try next? Getting the multimeter and checking power to RGB socket?
You could try cleaning the drive heads first. Use a cotton bud with alchohol and rub the heads lightly, just to rule floppy drive out. Then check power using multimeter, and if that doesnt reveal anything you are looking at a faulty chip probably. Sounds like you can rule the CIA chips out, my next guess would be the RAM, which is soldered on board and hard to remove if you dont have experience. Have you pressed the Agnus chip down to make sure its firmly socketed?
Edit: Ignore comment about RAM for now, its probably not that - I was forgetting that your modulator isnt outputting.
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It could be a dozen things. Load Workbench first (if you have it) and then insert the disks they could come up as bad and that might be normal depending on the disk. But at least you should get an error of some type.
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The pinout of the PSU can be found here:
http://www.hardwarebook.info/Amiga_500/600/1200_Power_Supply
And for a photo:
http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_Power_supplies/body_amiga_power_supplies.html
When using a multimeter, hold the common ground probe of the meter (usually black) to pin 2 - common ground. Then use the other lead (usually red) and hold on the voltage pins (1, 3 and 5) one at a time. You need both probes to touch one pin each to get a reading. Sorry for sounding too informative but I do not know how much electric/electronic skills you have.
Maybe that you can borrow a multimeter from can help you to check? Ask for help but stay with that person during the test and see what he/she does. And ask questions. Learn. And then get your own multimeter. For just checking basic voltages you do not need an advanced one. I paid ~AU$20 (~GBP14) for the one I have. And it's a decent one to to basic stuff.
Good luck!
Thanks mrknight,
Got myself a multimeter, think you are right it is a PSU problem. Tried black lead on pin 2, and put red lead on pin 1,3 and 5. Nothing at all showing. So tried black lead on pin 4, signal ground (going by the diagram). Results:
Pin 1, 10.9v
Pin 3, 26.2v
Pin 5, 0.0v
Pretty scary! Does this explain why modulator not working, does it mean that there is no 5v supply going into the computer?
Would getting a new PSU solve all my problems?
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It could be a dozen things. Load Workbench first (if you have it) and then insert the disks they could come up as bad and that might be normal depending on the disk. But at least you should get an error of some type.
Put in workbench disk, it does load for quite a while, can't remember if this is normal. When it eventually stops, there is something showing on the screen, but the picture is so bad can't see if it is anything, or just more static!
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You could try cleaning the drive heads first. Use a cotton bud with alchohol and rub the heads lightly, just to rule floppy drive out. Then check power using multimeter, and if that doesnt reveal anything you are looking at a faulty chip probably. Sounds like you can rule the CIA chips out, my next guess would be the RAM, which is soldered on board and hard to remove if you dont have experience. Have you pressed the Agnus chip down to make sure its firmly socketed?
Edit: Ignore comment about RAM for now, its probably not that - I was forgetting that your modulator isnt outputting.
Have cleaned the heads on the drive as best as I could, I reckon you are right, and that it is a PSU problem, tested outputs. Don't think they are what they should be!
Pressed the Agnus chip, it was fine. If it is as simple as the PSU not working, problem may be solved, just have to look on ebay!
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Thanks for everyone's help.
This may be better than trying to reply individually! It took me a while to be able to get to a shop to get a multimeter. This is all new stuff to me, never thought I would be mucking about trying to fix a computer!! I'm happy to be learning though, thanks for your patience!!
I posted results of testing the PSU outputs, here they are again Pin 1, 10.9v, Pin 3, 26.2v and Pin 5, 0.0v
Seems like there is no 5v going into the machine. Sounds like that is the cause of all the problems?
My concern was how this all occurred just from moving the machine! But then it is over 20 years old!!
What should I test next?
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Thanks for everyone's help.
This may be better than trying to reply individually! It took me a while to be able to get to a shop to get a multimeter. This is all new stuff to me, never thought I would be mucking about trying to fix a computer!! I'm happy to be learning though, thanks for your patience!!
I posted results of testing the PSU outputs, here they are again Pin 1, 10.9v, Pin 3, 26.2v and Pin 5, 0.0v
Seems like there is no 5v going into the machine. Sounds like that is the cause of all the problems?
My concern was how this all occurred just from moving the machine! But then it is over 20 years old!!
What should I test next?
I am not sure you've measured using the correct ground pin. If there was no 5v you wouldn't get the image of the hand holding the disk on the white background etc. The +5v powers most of the logic chips so 0v would mean nothing happening at all. Put the black wire of the multimeter on signal ground and see what voltages you get, and then try the black wire on the shielding ground and see what you get.
It's sometimes best to actually measure the voltages under the board whilst the amiga is powered up - that way you get 'under load' voltages which can vary wildly from what you measure coming out of the PSU when its not connected to the Amiga. I've seen +16v on 12v line drop to +12v when connected to the amiga etc.
EDIT: I've re-read and realised you said PIN 5, not the 5v line =)
Pin 1 is 5v
Pin 3 is +12v
So your +12v is mega high - could have damaged the FDD or modulator.
And your +5v is very high also - again could have damaged chips.
Check the voltages under load as ive described and use your multimeter on the pins under the board where the socket mounts the PCB. See what you get under load, just to be sure.
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I am not sure you've measured using the correct ground pin. If there was no 5v you wouldn't get the image of the hand holding the disk on the white background etc. The +5v powers most of the logic chips so 0v would mean nothing happening at all. Put the black wire of the multimeter on signal ground and see what voltages you get, and then try the black wire on the shielding ground and see what you get.
It's sometimes best to actually measure the voltages under the board whilst the amiga is powered up - that way you get 'under load' voltages which can vary wildly from what you measure coming out of the PSU when its not connected to the Amiga. I've seen +16v on 12v line drop to +12v when connected to the amiga etc.
EDIT: I've re-read and realised you said PIN 5, not the 5v line =)
Pin 1 is 5v
Pin 3 is +12v
So your +12v is mega high - could have damaged the FDD or modulator.
And your +5v is very high also - again could have damaged chips.
Check the voltages under load as ive described and use your multimeter on the pins under the board where the socket mounts the PCB. See what you get under load, just to be sure.
Ok, sorry about confusing post. When testing PSU unloaded (not plugged into machine), with black connector on Pin 2, always had a zero rating when red connector put onto Pin 1,3 and 5. So had another look at the diagram and put black connector onto Pin 4 Signal ground, then got those readings.
Have been testing PSU underload, took mother board completely out of machine, but was reluctant to bend back metal casing, as I don't think I'll ever get it back in place.
So worked which pin is coming out through the inside of the connection.
Got some very varied results. When putting black connector on Pin 2, there is some reading, strange how there was nothing when it wasn't plugged into the machine.
Anyway tried lots of the chips and floppy power supply, mono output, etc. Both with black connector on Pin 2, and Pin 4.
The mono output measures 3.5v with both,
RGB output measures 10.4 Down to 3.1, depending which pin red connector is placed on. So I suppose that there is one pin that is the power source for the modulator? You can see that I know absolutely nothing about electronics.
Sorry if this seems too long winded..
Other results are: with black connector on Pin 2;
DENISE 2.0v
ODD CIA varies between 2.3 and 10.6v (depending which pin on chip)
EVEN CIA 10.4v highest
PAULA 10.3v
GARY 10.6v
Trap door 8.6v
Floppy power source 10.6v
And with black connector on Pin 4
DENISE 8.1v
ODD CIA 10.4v
EVEN CIA 10.4v
PAULA 10.3v
GARY 10.6v
Trap door 8.3v
Floppy power source 10.6v
I've realised that certain pins on the chips carry the power, so the low readings should probably be ignored when there is a higher reading across the whole board of around 10.6v?
Hope that makes some sense!
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There's something wrong with your ground connection... 10+V all over the board would fry just about everything.
E.g., you can use the board's screw holes for ground reference, they're definitely grounded. Then, check the two outer contacts of floppy disk power - they should read 5V and 12V.
You're not by any chance using an analog multimeter that's severely decalibrated? The needle needs to be trimmed to 0 when it's idle.
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There's something wrong with your ground connection... 10+V all over the board would fry just about everything.
E.g., you can use the board's screw holes for ground reference, they're definitely grounded. Then, check the two outer contacts of floppy disk power - they should read 5V and 12V.
You're not by any chance using an analog multimeter that's severely decalibrated? The needle needs to be trimmed to 0 when it's idle.
Right, oh dear! I'm using a Ginometer M-830B, no real instructions on how to use it. So turned dial to 200V~
Checked again with black connector on a screw hole:
Left hand floppy pin 26v
Right hand floppy pin 10.5v
Should I be very worried?
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So turned dial to 200V~
Sounds to me that you have set the multimeter to measure AC. You need to do the reading in DC. See if you have a range setting for DC or VDC.
Maybe post a photo of the multimeter with the probes attached?
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Sounds to me that you have set the multimeter to measure AC. You need to do the reading in DC. See if you have a range setting for DC or VDC.
Maybe post a photo of the multimeter with the probes attached?
^ Yes, you are measuring AC and its DC you need.
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Sounds to me that you have set the multimeter to measure AC. You need to do the reading in DC. See if you have a range setting for DC or VDC.
Maybe post a photo of the multimeter with the probes attached?
I see, the instructions don't explain what the symbols mean, then again the ~ symbol should have been obvious enough! I just googled the meter I've got, some images have VDC and ADC instead of just the symbols.
Ok, I had it set to this, as it appeared to give readings that were sensible:
[ATTACH]2798[/ATTACH]
Have now set it to this, 200 seems to be right...
[ATTACH]2799[/ATTACH]
Tested a few things again, with black lead on screwhole:
Mono output 2.0v
Left hand floppy pin 12.2v
Right hand Floppy pin 5.2v
ODD and EVEN CIA 5.1v
DENISE 3.0v
Does that sound a bit better?!
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I see, the instructions don't explain what the symbols mean, then again the ~ symbol should have been obvious enough! I just googled the meter I've got, some images have VDC and ADC instead of just the symbols.
Ok, I had it set to this, as it appeared to give readings that were sensible:
[ATTACH]2798[/ATTACH]
Have now set it to this, 200 seems to be right...
[ATTACH]2799[/ATTACH]
Tested a few things again, with black lead on screwhole:
Mono output 2.0v
Left hand floppy pin 12.2v
Right hand Floppy pin 5.2v
ODD and EVEN CIA 5.1v
DENISE 3.0v
Does that sound a bit better?!
Ok, you are getting there! The 5v and 12v sounds OK. Measuring mono isnt going to help as its a complex signal not really a source of voltage to measure in that way. Denise wont be 3v, you are probably checking a signal pin rather than vcc. I will check diagram later and tell you where to check for -12v, and there might be a -5v, I cant remember until I check the schematics.
Are you sure composite from the modulator isnt working, I mean are you sure you are connecting the composite cable into the video out and not audio in on the modulator - both sockets look the same.
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Ok, you are getting there! The 5v and 12v sounds OK. Measuring mono isnt going to help as its a complex signal not really a source of voltage to measure in that way. Denise wont be 3v, you are probably checking a signal pin rather than vcc. I will check diagram later and tell you where to check for -12v, and there might be a -5v, I cant remember until I check the schematics.
Are you sure composite from the modulator isnt working, I mean are you sure you are connecting the composite cable into the video out and not audio in on the modulator - both sockets look the same.
Excellent! Feels like I'm learning something too!
Just checked every leg on Denise, highest reading I get is 5.2v about half way along edge nearest to RGB output.
I've tried the RF out socket and Video out, no signal from either. I am unable to find out how to tune the TV properly because the remote doesn't work. However, I did find the right setting for the mono output. So leaving the TV on that channel, and swapping the cable ( while machine turned off!), between RF and Video, just get a blue screen. Which I think is what this TV does when nothing is happening.
I had tried to go through all 100 channels with no luck. And the settings menu, selecting the External to AV input. Even tried VCR, but nothing.
Does it sound like the modulator has stopped working? I was about to get an RGB to SCART cable anyway...
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Excellent! Feels like I'm learning something too!
Just checked every leg on Denise, highest reading I get is 5.2v about half way along edge nearest to RGB output.
I've tried the RF out socket and Video out, no signal from either. I am unable to find out how to tune the TV properly because the remote doesn't work. However, I did find the right setting for the mono output. So leaving the TV on that channel, and swapping the cable ( while machine turned off!), between RF and Video, just get a blue screen. Which I think is what this TV does when nothing is happening.
I had tried to go through all 100 channels with no luck. And the settings menu, selecting the External to AV input. Even tried VCR, but nothing.
Does it sound like the modulator has stopped working? I was about to get an RGB to SCART cable anyway...
It's an odd problem because you seem to be having a sync issue on mono composite as well dont you? That might be why colour isnt working through the modulator. If the modulator was faulty you should still get a stable mono output when the modulator is not connected, and the fact you are getting crashes leads me to believe theres fault on motherboard or the power is still in question, but unlikely to be causing a video sync issue - although its possible. You need to check the -12v line, because that could be causing a problem still.
If the power us OK (and weve not ruled out the power yet, whilst voltages seem ok you might have a tonne of noise on the power lines which would cause what you are seeing), then I am inclined to think that something is wrong with denise, the hybrid or supporting circuitry.
Could you take a few close up pics of the area around demise, and agnus, and garry / CIAs if possible - it might reveal something unhealthy visibly, eg a burn resistor, signs of heat damage, colour changes to components etc.
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Hope these photos will be close and clear enough..
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I'll definitely need help to trace the correct 12v line!
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Hope these photos will be close and clear enough..
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[ATTACH]2801[/ATTACH]
[ATTACH]2802[/ATTACH]
[ATTACH]2803[/ATTACH]
[ATTACH]2804[/ATTACH]
[ATTACH]2805[/ATTACH]
I'll definitely need help to trace the correct 12v line!
I can see the last attachment but the others aren't working for some reason?
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Don't think they all uploaded properly..try again!
[ATTACH]2806[/ATTACH]
[ATTACH]2807[/ATTACH]
[ATTACH]2808[/ATTACH]
[ATTACH]2809[/ATTACH]
[ATTACH]2810[/ATTACH]
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The file sizes are just a little past the limit of 97.7Kb. If I PM you my email, that may be better?
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Interestingly the CSYNC comes from Agnus, along with HSYNC and VSYNC. Not suggesting there's anything wrong with the CSYNC signal, but those are obvious signals springs to mind regards the sync issue you have with mono and the fact you are getting no colour at all. I know i've asked this many times now, but have you pressed the Agnus down hard to make sure she's firmly in her socket? Ideally personally I would remove her and re-seat her but you need the proper tool to do that or you will likely break the socket - so just press down and make sure the chip isn't loose at all.
If something was wrong with Agnus you would get crashes as well, but it's all very strange to be honest as I wouldnt expect video issues like this. Do you know anyone else who has a 500, so you can borrow a PSU just to rule out noise on the +5v line?
You could buy a cheap 500 off EBAY - there's one on there in Cheshire atm (collection only) which sounds OK minus a dodgy power socket and the floppy needing replacing, but it's like £10, which would give you a full set of chips, or worst case just use the whole other motherboard and re-solder the power socket and it should be good to go. Depends how desperate you are to repair it. It's sad but the value of these things has dropped so much that we are now at a time where many go to landfill rather than be repaired or sold, and the postage often outweighs the cost of the thing to start with.
I could take a look at it for you but the postage will likely be a killer. By the time you've posted it each way (lets say £10 for motherboard only), that's £20 and you might end up with £5 to £10 or parts, worst case full bank of RAM @ £20 or £30. You could buy another working A500 for between £30 to £60.
EDIT: Wierd, in the time i've just posted this comment the 2nd image from the bottom is now appearing OK as well. (can see bottom 2 atm).
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PM sent!
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Just looking at my notes from when I used to repair Amigas. If there is a fault we might be on the right tracks looking at Agnus. I've had one with incorrect CSYNC before and it was Agnus, although there are a few other things can cause it including an 74 series chip, and a resistor pack. Anyway, it's all speculation at this stage.
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EDIT: Wierd, in the time i've just posted this comment the 2nd image from the bottom is now appearing OK as well. (can see bottom 2 atm).[/QUOTE]
I reposted when I saw that only the last one appeared! Then I saw the limit on jpeg files!!
Took them all in digital macro. I checked the Agnus again, it's absolutely solid, it's a real bummer it going wrong so suddenly. Unfortunately I don't know anybody else who still has their Amiga, I'll have a look for that one on ebay, it's a bit too far to go to pick it up though. I was just hoping to play Alien Breed, and Z-out, and probably IK+!
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PM sent!
Sent the photos off to you!
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Sent the photos off to you!
I've had a good look at those close ups, everything looks good, no obvious signs of damaged resistors, chips or capacitors. The ROM looks like it has a patch in the bottom left of it where moisture has been on it but I doubt that has anything to do with the problem. You could try taking the ROM out and putting it back in just to make sure but typically you would get the red screen error if anything was wrong with the ROM.
The Agnus is an 8372A, which is the 1Mb chip RAM Agnus so you must have a rev 6a / 7 board probably, unless someone has replaced the Agnus before - but from looking at where pin 1 is I suspect it is an original chip on rev 6a / 7 board. It doesnt look pushed all the way in to me, I wonder if someones done the double sided sticky pad job on it. I recently bought an A500 where someone had removed the agnus, damaged the socket and then 'stuck' it back in the socket with a double sided pad, which is fine for a period of time but it means the chip doesnt sit as deep into the socket as it should. CSYNC, crashes and floppy drive errors can be all caused by the Agnus not sitting correctly (or having an internal fault).
I've rechecked regards -12v and the minus 12v shouldn't affect anything other than comms (serial port and parallel port) so I wouldnt worry about that for now.
Is it a UK console that you've had for years, not a US version or something?
You can typically pick up an Agnus 8372A for between £5 and £10 on EBAY, but I don't see any UK sellers at the moment. The difficulty with the Agnus is removing it very very very carefully in such a way that you don't damage the socket. Ideally you should use a PLCC extractor tool but they aren't always easy to use. The alternative and dangerous (if you dont be careful and dont know what you are doing) method is to use a jewlers screwdriver (very very thin screwdriver and put it under the little hole (looking at your photo) in the top right and lever under the chip a little (and I mean a little) bit, like a quarter of a millimeter of movement, then do the same with the bottom right hole / gap / slot call it what you will, again levering just a tiny tiny amount, repeat that process 4 or 5 times for each of the 2 corners and provided you hardly use any force at all it will lift out.
If the socket has become brittle (which they do over time) and you press too hard you will break the socket, which means desoldering the 84 pin PLCC socket and putting a new one on. I've done this recently for the 500 I bought - it was in a shocking state.
I think you should try another TV to see what if anything is different on the video outputs, check the pins of the video sockets on the back of the amiga as well to make sure none are bent and shorting on each other etc - i've seen that before from people ramming in the modulator when its not straight etc. If there's no difference on another TV, and pressing firmly on Agnus to double check its totally making contact (you could start the A500 up whilst you are pressing down firmly on it with your thumb), and you've not got another power supply to try (to 100% rule it out), then you are looking at a faulty chip or other component, so its then a question of how you go about getting replacement bits of EBAY etc, or just get a working / semi working 500 off EBAY as a doner.
Do you live in the UK or elsewhere?
EDIT: Removing Agnus - on your photo the slots to get under the chip are TOP LEFT and BOTTOM RIGHT, not TOP RIGHT!!
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Just looking at one of the pics again, can I see what looks like corrosion in the bottom right hand side of one of the pics? One with Agnus, in the bottom right theres a 74F244 and a black resistor pack next to it, the legs of that chip look a bit brown but its not very clear. Might be an idea to take a picture of that area there where the expansion memory card plugs into.
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Spotted something else as well - See the first picture with Denise, above Densise is 74HC245, and to the left hand side of it, there's a capacitor C40 (yellow), and to the left of that are 2 tracks on the circuit board. See the very left one, I cannot tell from the picture if that's corrosion or not, can you take a look at it and see if it looks damaged there, or is it a plastic coating or something?
Your multimeter should have a continuity test mode hopefully? You can check that the track is not damaged by putting meter onto continuity test mode, put one wire on a contact that one side of the track goes to, and your other prong on something connected to the other side of the track. You need to look at the board first to follow where it goes to - usually a solder point on the board or a chip pin.
EDIT: Hmmm, the plot thickens. Looking at that area of the board its not clear to me 100% but I am wondering if that capacitor has shed its load of electrolyte on the board - it could be that capacitor. Please take a close look where i've said to check that track and see around the big purple / blue capacitor above, is there gunk around it on the board?
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Here is that area around the expansion port: Think it may have been in shadow in earlier pic.
[ATTACH]2812[/ATTACH]
I'll mail you a clearer one.
It is a 6A board, pushed the Agnus as hard as I dare to. As far as I know, this is the first time it's been opened up. Security tags were still on it. This was a friend of mine's machine, we played on it back in the day, he gave it to me when he was chucking it out and it's been in a box for at least 5 years.
My own Amiga was lost by being thrown away by a family member, along with all games and a great comp pro extra!
I'm in the UK, in Essex.
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Looks like the second pic got attached as a thumbnail, don't know how that happened!
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Here is that area around the expansion port: Think it may have been in shadow in earlier pic.
[ATTACH]2812[/ATTACH]
I'll mail you a clearer one.
It is a 6A board, pushed the Agnus as hard as I dare to. As far as I know, this is the first time it's been opened up. Security tags were still on it. This was a friend of mine's machine, we played on it back in the day, he gave it to me when he was chucking it out and it's been in a box for at least 5 years.
My own Amiga was lost by being thrown away by a family member, along with all games and a great comp pro extra!
I'm in the UK, in Essex.
Thanks, they look OK. See some of my other posts above ^
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Spotted something else as well - See the first picture with Denise, above Densise is 74HC245, and to the left hand side of it, there's a capacitor C40 (yellow), and to the left of that are 2 tracks on the circuit board. See the very left one, I cannot tell from the picture if that's corrosion or not, can you take a look at it and see if it looks damaged there, or is it a plastic coating or something?
Your multimeter should have a continuity test mode hopefully? You can check that the track is not damaged by putting meter onto continuity test mode, put one wire on a contact that one side of the track goes to, and your other prong on something connected to the other side of the track. You need to look at the board first to follow where it goes to - usually a solder point on the board or a chip pin.
EDIT: Hmmm, the plot thickens. Looking at that area of the board its not clear to me 100% but I am wondering if that capacitor has shed its load of electrolyte on the board - it could be that capacitor. Please take a close look where i've said to check that track and see around the big purple / blue capacitor above, is there gunk around it on the board?
It looks like plastic coating covering that track. Had a gentle scratch with small screwdriver, it comes off a little bit, revealing copper track beneath.
Tried a continuity test, traced that track to the E403 by the Capacitor you mentioned and a solder port near the E703.
The display begins with a 1 showing, which I take means infinity. Get a reading of 01.3 should that be reading 0 though? Could that mean that the track is a bit damaged after all?
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Sorry, had a look for any gunk around that capacitor. It's clean, no leakage of any kind. Makes it even more mysterious.
I'll have to go back to a friend's to check on their TV, it could take a few days to be able to do that though..
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Faults
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Modulator doesn't seem to be outputting RF signal at all?
Composite Mono works OK, but you mentioned its not stable - could you explain what you see?
Floppy seems problematic, or at least it seems to crash when loading games with the power LED flashing.
What we know:-
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Same behaviour without Floppy Drive connected.
Same behaviour without Keyboard connected.
Same behaviour without RAM expansion connected.
Same behaviour with CIA chips swapped around.
Chips seated correctly.
Doesn't appear to be any visible damage - have you looked underneath the board to see if anything looks burnt or damaged at all?
+5v and +12v appear acceptable, but we don't know whether theres noise or ripples on those lines, lets assume the PSU is OK because I would expect different behaviour than no video output and floppy problems.
Your initial post was that you had floppy problems, and mentioned the power light flashing - we need to expand a little if we can, what games do you have to test with, load them up, see how far they get before you get the flashing light and what happens on screen then - does it go to the 'Guru Meditation' screen or what?
If you leave the Amiga powered on without a disk, do you get the Kickstart hand image up OK and does it look corrupt in anyway graphically? At that point you should hear the drive keep clicking as its looking for a disk - do you hear that? If you then leave it on for like 20 mins, does it just sit there waiting for the disk OK or does that crash at any point?
Regards the games you have, you need to test each one and see what happens (and listen), do you get loading screens on some but not others, do you get any sound out at all? And when it crashes exactly what happens, does it crash at the very same point on the same game every time or not? Are there any games that load at all, have you tried a workbench disk?
And when the power light flashes, count the number of times it flashes and let me know how many you see.
Check on another TV like you said - just to rule it out! I am wondering if the Agnus has somehow gone into NTSC mode, either through bad connection or internal fault, that said games normally load when its in NSTC mode on a PAL console with PAL games, they usually crash a bit later.
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It looks like plastic coating covering that track. Had a gentle scratch with small screwdriver, it comes off a little bit, revealing copper track beneath.
Tried a continuity test, traced that track to the E403 by the Capacitor you mentioned and a solder port near the E703.
The display begins with a 1 showing, which I take means infinity. Get a reading of 01.3 should that be reading 0 though? Could that mean that the track is a bit damaged after all?
That 1.3 means 1.3 ohms probably which is OK as its very low resistance. The large number as you say means very very high resistance so no connection. You can use that mode of your multimeter to test fuses and bulbs - so keep the meter ;)
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Sorry for going a bit off topic here, but is this video available online? And if so, do you have a link? It sounds very interesting and I'd like to learn more:)
I can't remember but I think it was this one:-
https://www.youtube.com/watch?v=DXRvCnmLj7A
Look at his channel after you've watched that, he's got several more videos including another 2 or 3 related to that retro repair event.
I think he might have been specifically refering to CIA's in the 64 and 128, but I know the CIA's go for the same reason in Amigas. The number of CIA's i've replaced far outweighs any other component, although these days it seems to be RAM - all that DRAM in older machines is finally giving up the ghost it seems.
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Incidentally, here's are the schematics for your revision PCB:-
http://amigarealm.whdownload.com/archives/Amiga%20Schematics%20and%20Manuals/A500_R6a_7.zip
It might seem confusing to start with but there's a lot you can learn by looking that these - like how each chip connects to the next chip etc, and since you've got a multimeter now you could put it on resistance and check some of the resistors - the values are on the diagram. NOTE: You sometimes don't get an accurate measurement of resistance whilst measuring a resistor in circuit, so you occasionally have to desolder one end in order to measure it properly.
If you take a look at the page with Denise on you can see the _CSYNC input into Denise, and if you look at the Agnus page you can see _CSYNC as an output. I personally suspect something wrong with either Denise or Agnus, but it might not be the chips themselves, it could be supporting resistors, or capacitors etc. Anyway, don't bog yourself down with this stuff too much just yet, read 3 or so posts back and see my summary of where we are - try and reply to those questions if you get time.
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I can't remember but I think it was this one:-
https://www.youtube.com/watch?v=DXRvCnmLj7A
Look at his channel after you've watched that, he's got several more videos including another 2 or 3 related to that retro repair event.
Thank you! I have added the video to my 'watch later' section.
Laughy, when using a multimeter you should set the measuring range closer to the level you want to measure to increase accuracy. You are measuring a 12V level using a range of 200V. You can easily set your multimeter to 20V.
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Laughy, when using a multimeter you should set the measuring range closer to the level you want to measure to increase accuracy. You are measuring a 12V level using a range of 200V. You can easily set your multimeter to 20V.
Thanks mrknight! I did wonder what the numbers referred to exactly, but no explanation in the instructions at all! I set it to 20v and tested the power supply. It read 12v, -12v, and 5v. So it seems to be fine!
I'll hopefully be able to go through a lot of the tests that GadgetUK has mentioned, later on today
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Sorry for delay, didn't get to test Amiga on another TV as hoped. Have gone through the tests from GadgetUK with the TV I've got, for now until I get to another TV, hopefully this weekend..
Here is a photo of the kickstart screen in mono...
[ATTACH]2833[/ATTACH]
Picture has interference, which I hoped was due to TV not being tuned in properly. I have cleaned the remote controller, and got it working. It doesn't seem to have more functions than the buttons on side of TV, like I had hoped! Seems that it can't be more finely tuned.
Results of tests so far..
1. Haven't been able to verify if modulator working or not yet.
One good thing though! Found a friend who still has his old Amiga500!! But has lost the modulator, I'm going to see him on friday, taking my Amiga. At the very least to see if my modulator works on his Amiga, unfortunately he has no compatible TV.
3 Games the drive crashes on:
Nitro. After a few seconds, drive stops with both power and drive light on, no flashing. No signal going to TV.
Project X. Drive turns once, stops, lights on, no flashing. Drive makes one click, then 'bad disk' noise of continual clicking.
Turrican 2. Two clicks, one turn. Stops, lights on but not dim.
Workbench. Loads much more than other disks, lots of turning and clicking, sounds good. Loads for about 2 minutes, stops, drive light not on. No signal to TV.
No loading screens at all on any games tested.
Kickstart image is up, as photo shows. After 20mins, still up, computer doesn't spontaneously crash.
Drive makes it's normal, rhythmic clicking sound.
I will carry out all tests again on a different TV. Hopefully this weekend, if the modulator has not stopped working!!
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Sorry for delay, didn't get to test Amiga on another TV as hoped. Have gone through the tests from GadgetUK with the TV I've got, for now until I get to another TV, hopefully this weekend..
Here is a photo of the kickstart screen in mono...
[ATTACH]2833[/ATTACH]
Picture has interference, which I hoped was due to TV not being tuned in properly. I have cleaned the remote controller, and got it working. It doesn't seem to have more functions than the buttons on side of TV, like I had hoped! Seems that it can't be more finely tuned.
Results of tests so far..
1. Haven't been able to verify if modulator working or not yet.
One good thing though! Found a friend who still has his old Amiga500!! But has lost the modulator, I'm going to see him on friday, taking my Amiga. At the very least to see if my modulator works on his Amiga, unfortunately he has no compatible TV.
3 Games the drive crashes on:
Nitro. After a few seconds, drive stops with both power and drive light on, no flashing. No signal going to TV.
Project X. Drive turns once, stops, lights on, no flashing. Drive makes one click, then 'bad disk' noise of continual clicking.
Turrican 2. Two clicks, one turn. Stops, lights on but not dim.
Workbench. Loads much more than other disks, lots of turning and clicking, sounds good. Loads for about 2 minutes, stops, drive light not on. No signal to TV.
No loading screens at all on any games tested.
Kickstart image is up, as photo shows. After 20mins, still up, computer doesn't spontaneously crash.
Drive makes it's normal, rhythmic clicking sound.
I will carry out all tests again on a different TV. Hopefully this weekend, if the modulator has not stopped working!!
That is more than a bit of noise, that picture is well out. Just to confirm you are connecting from mono composite out to a composite in on the TV and you arent plugging it inti a uhf / rf socket? Composite is not 'tuned in' it just connects and you select the composite / av in/ aux on the tv and thats it.
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I cant help but wonder if all thats wrong is the FDD and all these video issues are your TV. If it doesnt work on another TV its probably Agnus, that said the reason I think there might not be fault with a chip on the Amiga is I would expect the power light to flash on a crash when it dumps to the guru screen. The behaviour looks like a disk drive read problem and its possible the display problems are the TV.
You really need to prove one way or another on a different TV.
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Sure, just checked, I've got the cable going from mono out on the Amiga into the ANT IN on the TV. It's the only socket it will fit into.
Tried to select AV input on the TV menu, but says 'no signal' when I try that.
Does this sound like an issue with the sync from Agnus to Denise?
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Just to expand on my comment above about where you are connecting composite out of the Amiga...
Typically composite connector is yellow in colour. If you are connecting to a modern TV dont make the mistake of plugging into one of the 3 composite red, green or blue sockets - they are marked composite so you could do it by mistake. Ive got no idea what the picture would look like if you did that. You also should use a composite lead to connect - not the RF lead that you use with the modulator - the noise makes me think you are using that lead possibly??? It wont connect properly and leave the signal or ground floating.
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Thanks, your message came through while I was checking!
I will try it on the TV I first tested it on as soon as I can. If it does work, and turns out that this TV is the problem, do you think It's worth getting the RGB to SCART cable, and hoping it will work with that?
I ask because, I had a quick chat initially with someone at Amigakit, who told me they use the same TV for testing, and it would be ok.
I will probably need to get a new FDD in any case by the sound of it..
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I cant help but wonder if all thats wrong is the FDD and all these video issues are your TV. If it doesnt work on another TV its probably Agnus, that said the reason I think there might not be fault with a chip on the Amiga is I would expect the power light to flash on a crash when it dumps to the guru screen. The behaviour looks like a disk drive read problem and its possible the display problems are the TV.
You really need to prove one way or another on a different TV.
Sure, just checked, I've got the cable going from mono out on the Amiga into the ANT IN on the TV. It's the only socket it will fit into.
Tried to select AV input on the TV menu, but says 'no signal' when I try that.
Does this sound like an issue with the sync from Agnus to Denise?
OK, progress. See my last post. You are connecting composite mono to the RF in on the TV. That won't work.
Next step is to either retry modulator with that same socket on TV and make sure you scan through each channel as you try to program the channel. If you cannot do that, just order a scart cable from ebay for the a500, but make sure your TV does have a free scart socket.
I think theres nothing wrong here other than dirty heads, and possibly not even that...
Edit: how did you test with modulator to start with? I am suspecting you just changed channels and didnt actually 'tune a channel' whilst amiga was connected and powered up? Sorry if its a stupid question but ive got to ask. Worst case is perhaps your TV doesnt like the modulator signal or it wasnt all connected up properly when you tuned a channel in.
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Just to expand on my comment above about where you are connecting composite out of the Amiga...
Typically composite connector is yellow in colour. If you are connecting to a modern TV dont make the mistake of plugging into one of the 3 composite red, green or blue sockets - they are marked composite so you could do it by mistake. Ive got no idea what the picture would look like if you did that. You also should use a composite lead to connect - not the RF lead that you use with the modulator - the noise makes me think you are using that lead possibly??? It wont connect properly and leave the signal or ground floating.
Right, yes! Luckily I found I did have the Yellow, white and red composite cable lying around. I just tested it while trying with the usual aerial cable.
Took that out as you said, and put the hello cable into the video out on the modulator, and into AV in on the TV. Kickstart screen is perfect!!
Sorry for the mucking around, I had no idea the old RF cable wouldn't work as it was fine on the TV I tested it on first. Is that due to the TV's age?
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Just for your enjoyment! Again, I apologise for all that...
[ATTACH]2834[/ATTACH]
I have tried to clean the FDD, but now perhaps I should take it apart properly and clean the heads?
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See above. Ive dropped u an email as well just to say also check when tuning TV into modulator that you arent looking for a digital signal - TV needs to look for an analogue signal.
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Edit: how did you test with modulator to start with? I am suspecting you just changed channels and didnt actually 'tune a channel' whilst amiga was connected and powered up? Sorry if its a stupid question but ive got to ask. Worst case is perhaps your TV doesnt like the modulator signal or it wasnt all connected up properly when you tuned a channel in.
Yes, that was my initial problem with the TV. I had no way of scanning for a signal to tune it in, I thought the remote would have more options than the controls on the TV itself. Now that I have fixed the remote, I found out that there is no difference!
There doesn't seem to be any option to scan frequencies with this TV. I have plugged a DVD player in, and it just finds it. However, on the TV I tested the Amiga on, which is about the same age, I had to scan and tune the signal in.
I haven't had to do anything and it's fine!
In fact I have just loaded up Workbench, and that is fine too! Can't believe it!
Perhaps the game disks I have been trying have just become dirty?
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Woohoo! Progress!!
Yes, take FDD out. Then take lid off the drive (you dont need to take any other parts off). Some drive lids held on with 1,2 or maybe 3 ver small screws, but some amiga drive lids are taped at the sides, if its one if those just peal that tape / silver foil off and youre in.
Use a damp cotton bud with alchohol and gently rub the heads from side to side around 10 times each. The bottom head is easy, top one usually tricker - dont bend it upwards, just lift it gently until you get cotton bud onto it.
Also clean any hair or dust out of the assembly while u are there.
If it was taped at the sides u can replace with selotape.
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See above. Ive dropped u an email as well just to say also check when tuning TV into modulator that you arent looking for a digital signal - TV needs to look for an analogue signal.
Thanks! I haven't had to tune a TV for a long time...
I've just checked on the TV menu, I've got the input as AV:VCR. The picture is good.
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http://en.m.wikipedia.org/wiki/Occam's_razor#section_1
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Something unbelievable has happened!
I have just loaded up Project X, I can only apologise for wasting you time...but it seems like the signal not being received by the TV somehow stopped the disk drive from loading games, is that possible?
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Something unbelievable has happened!
I have just loaded up Project X, I can only apologise for wasting you time...but it seems like the signal not being received by the TV somehow stopped the disk drive from loading games, is that possible?
Nah, the video wouldnt likely affect game loading. You may have had a loose chip earlier on before you started looking inside (Agnus does sometimes cause the flashing led issue that seemed to dissapear). Also remember you swapped the CIAs around, one might be faulty and that might be why its now loading games.
I wouldnt do anything else now other than play some games to see how it runs, is it stable etc.
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Nah, the video wouldnt likely affect game loading. You may have had a loose chip earlier on before you started looking inside (Agnus does sometimes cause the flashing led issue that seemed to dissapear). Also remember you swapped the CIAs around, one might be faulty and that might be why its now loading games.
I wouldnt do anything else now other than play some games to see how it runs, is it stable etc.
Do I ever feel like even more of an idiot than normal...
Just don't know what I was doing wrong. I will play some more games, getting Alien Breed soon. And have to get a couple of joysticks. Got to remember what screws went where, and put it back together...
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Do I ever feel like even more of an idiot than normal...
Just don't know what I was doing wrong. I will play some more games, getting Alien Breed soon. And have to get a couple of joysticks. Got to remember what screws went where, and put it back together...
Don't feel bad, these things happen. When you put it back together dont put too long screws in the 3 holes nearest the front of the case - you can screw though the top of the case if you arent carefull.
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I owe you a beer sometime.
Thanks
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I owe you a beer sometime.
Thanks
No worries! At least we've learn't some stuff along the way. Keep that multimeter and use it to test fuses, batteries and power supplies in future.
Have fun and let us know if anything else crops up!