A500 disk drive stopped!

[Laughy]

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!

[Laughy]

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?

[Laughy]

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:


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Have now set it to this, 200 seems to be right...

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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?!

[Laughy]

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...

[Laughy]

Hope these photos will be close and clear enough..

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I'll definitely need help to trace the correct 12v line!

[Laughy]

Don't think they all uploaded properly..try again!
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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?

[Laughy]

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+!

[Laughy]

PM sent!

Sent the photos off to you!

[Laughy]

Here is that area around the expansion port: Think it may have been in shadow in earlier pic.

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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.

[Laughy]

Looks like the second pic got attached as a thumbnail, don't know how that happened!

[Laughy]

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?

[Laughy]

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..

[Laughy]

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

[Laughy]

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...
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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!!

[Laughy]

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?

[Laughy]

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..