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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: circlip on December 21, 2007, 04:37:47 AM
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Hi all,
Aussie Amiga newbie here!
I put a post in the introductions section, but can't find it now.
Anyways, I have just bought a used Amiga 500 setup with "the lot" sold as an "as is" auction on ebay. No software for it yet, but I'm going to hopefully buy WB1.3 next week.
I have turned it on to see a nice "insert WB 1.3" screen, but occasionally it will reset itself. Sometimes it will do it a few times in a row, sometimes I can leave it for 5 minutes without a hitch, sometimes after the 5 minutes it'll do it's reset thing again. Also the "Caps Lock" key is sometimes flashing. As I have no WB yet, I have no way to test the keyboard, so I don't know if the keyboard is OK.
Does anyone have any idea of which part I could replace? Power supply, main unit, or motherboard? I can easily get these from ebay and other sources here in Australia.
I've tried shaking the power supply, and the connection to the main unit is fine, I've tried shaking the keyboard unit, fine too.
Any ideas anyone?
Circlip.
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Is there something in the trapdoor? It getting hot used to make my A1200 go nuts before I started keeping it raised above the desk with milk jug caps.
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Check the belly of the 500 and see if there is a RAM card in there. Some have NiCad batteries that have surely leaked by now and done their deed so remove it and see if it helps cure the problem...
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Some chip on the mobo may have bad contact into its socket - I once had an A500 with Agnus contact problems resetting itself - or giving green screen.
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Wow guys, very quick replies! Thanks!
No extra ram cards, and I opened my A500.
Is it true that A500's have bcakup batteries like pc's do? I couldn't find one, and there is no battery corrosion anywhere, so I guess that's a good thing.
I did find the floppy power cable a bit out, but I could've knocked it, so I just pushed it back in.
I also tried to gently press a few of the major chips, in case of a bad contact or whatever.
I put it all back together, and haven't seen any "resets" but next week when I start using it for real, I will then know. I tried a couple CTRL + Amiga + Amiga, and still ok, tried a few power off + on again, fine.
Thanks very much guys, I will let all know if I run into trouble next week when I'm actually doing stuff with Workbench 1.3
Actually, one more thing.... is the rapidly flashing CAPS LOCK key a problem though? It will do it sometimes, and sometimes it's steadily on.
Circlip.
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That sounds to me like a keyboard controller problem (esp CapsLock blinking).
Mine a500 and many others (all?) have this problem: the plastic sheet that isolates controller pins from metal shielding can be pierced with sharp pins and make shortcircuit. If that is the case, first check the two identical capacitors that are symmetrically located on pcb and use some extra isolation.
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How do I isolate them Defender? Does that mean my keyboard could be useless when I get it going, or just a weird Caps Lock light?
Circlip
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@circlip
A500's don't have an internal battery. That's the reason why there are those clock expansion things. Before them, you had to reset the time with every boot-up. Or, like probably everyone, ever, not worry about setting the correct time at all. :-)
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Hmmm... just booted up again, and it's still doing the reset thing. Do you guys think I should shell out for a new keyboard unit, or is there a few other things I could try?
Thanks for all your help on this....
Circlip.
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I would unplug the keyboard and use it for a while to see if it is indeed the KB that is causing the reboots...
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@ TjLaZer
Hmmm... don't know if it's the KB itself, but I meant replacing the WHOLE THING (keyboard that houses everything else inside), would cost about 50 bucks on ebay, and I'd have to go money borrowing, lol.
Shame that my nearest Amiga repairs shop in Sydney NO LONGER supports Amiga. :boohoo: So I'm stuck either figuring out what's wrong, or buying another whole unit, and keeping this one for spare parts.
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Please don't mistake the actual keyboard with the entire computer. ;-)
I'd try pushing down all socketed chips first, then another power supply second.
I have had A500 PSU's that reset the machine intermittently.
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@circlip
Maybe you're not in Australia afterall, but actually in New Zealand by mistake, and what you are experiencing are the mandatory power outages.
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I hade the same problem but on a A1200 and it was a faulty PSU. If you can try with another psu and see if it's ok.
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Well,
I ahd another go, and shook the PSU a bit. It sounds like it has something rattling inside, and I can feel something big shifting in there.
Is it safe to open the power supply with it unplugged without electrocuting myself or something?
@ Jope: Sorry about the Keyboard mistake, I just called it a "keyboard unit" maybe I should call it a "main unit" or something, or A500 unit next time?
@weirdami, NZ couldn't be as bad as Papua New Guinea or Indonesia with their power outages, I've lived in both, annoying when chatting or working on an important file!! :crazy:
The rattling in the PSU sounds like a small loose screw or something.
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Make sure you've got the sound hooked up to your TV or WHY and listen out for 'machine gun' style interference (technical term - ahem). If you hear such noises - it'll probably caused by a faulty PSU.
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I've never received so much help from a forum before guys, so thanks for all your hints and tips! We shall get this thing going somehow!
Hi DrDekker.
I plugged it directly into the Audio/Video ports of the TV, and I didn't get any noises. If you meant for me to use the A520 Modulator, I haven't got the right cable for the RF OUT, I'm only able to use the A/V ports.
I'm still intrigued by the rattling noise though.
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circlip wrote:
I've never received so much help from a forum before
You've been going to the wrong forums then! :lol:
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circlip wrote:
If you meant for me to use the A520 Modulator, I haven't got the right cable for the RF OUT, I'm only able to use the A/V ports.
The audio ports are just fine. Also check the keyboard connector on the motherboard - a bad connection here can sometimes cause random reboots.
Another cause can be the keyboard controller chip located on the keyboard. On early models the chip is socketed (red LED for floppy drive?) - on later models (yellow/orange LED - e.g. A500+) the chip is soldered directly. If it's the former - just lever the chip out a little and press it back home. Since the fault is random (ish), it could be just a poor connection. If the capslock light flashes in a particular sequence it usually indicates there's a mainboard fault or the keyboard controller chip has gone west.
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Hi DrDekker again.
The led colours on the keyboard are: power=orange, floppy=greenish
The Caps Lock light doesn't have any sequence as such, either I switch it on and it's steady, or I switch it on and it just flashes continually. Want me to crack it open again? (this is gettin fun. :-) )
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The led colours on the keyboard are: power=orange, floppy=greenish
That sounds like an A500+ ... (or I suppose it might be a late A500, I can't recall which way round they are on my 500+, are they the right way round?). What colour is the boot screen when there is no floppy in the drive, what version Kickstart is it?
Ed: ok, you're running it into some green-screen monitor (as you said in another thread), so what does the boot screen tell you...
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Yes, meega, it's a green-screen. But I have plugged it into the tv once or twice. Startup screen "white with blue floppy with words "Workbench 1.3"", so I'm assuming it's a kickstart 1.3 if I'm correct.
EDIT: Does anyone think a motherboard replacement will (hopefully) fix my problems? I found a cheap one which I could buy next week. It has no chips.. so if a chip is the problem, I might make no headway.
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There is a difference between Kickstart and Workbench, an A500Plus will also boot into 1.3 and give the blue Workbench display if you put a 1.3 system disk in the floppy drive. Try removing the floppy, and give it the three-fingered salute (Ctrl+Amiga+Amiga) and tell us what it shows then.
(But you should know if it's an A500Plus, because it says that on the badge on top of the case.)
And further eds: I might just be wasting your time, you might well be entirely correct. The keyboard looks like either an A500 or else a US layout, A500Plus uses the International keyboard with a different Return key.
Also, apologies if I'm getting this wrapped around the wrong way... Rereading your posts makes me think it is indeed an A500.
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Hi meega,
Well, I don't have workbench yet...
(that was a floppy I simply tried to boot unsuccesfully with, after reading further into transferring files to an Amiga (I'm getting workbench 1.3 hopefully next week))
But basically it asks for WorkBench 1.3... white screen, blue coloured disk icon. There is no "Plus" badge anywhere.
EDIT: If anyone wants screenshots of anything for further investigating (inside or outside of the A500) I can make them asap.
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Do you have a multimeter handy? then you could check if the psu is giving out the right voltages.
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circlip wrote:
Yes, meega, it's a green-screen. But I have plugged it into the tv once or twice. Startup screen "white with blue floppy with words "Workbench 1.3"", so I'm assuming it's a kickstart 1.3 if I'm correct.
EDIT: Does anyone think a motherboard replacement will (hopefully) fix my problems? I found a cheap one which I could buy next week. It has no chips.. so if a chip is the problem, I might make no headway.
Most likely it is either a chip, bad contact or psu. I would rather invest in a whole machine as a500 goes for very cheap anyways.
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I do have a multimeter, I can give it a shot. I saw an Amiga 500 on ebay for about 50 bucks (excluding postage) and I don't want to fork out that much if I can avoid it.
EDIT: Ok, I have the pinout diag, here on the bottom of the PSU.
------\ /------
* +12V \ / * SIGNAL GROUND
\/ |
* -12V |
* SHIELD GROUND *| -5V
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So where should I put each probe? I especially don't know how to test the 5V lines. Forgive me, I've only tested a few "simple" things with a multimeter, never an A500 PSU. :-?
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circlip wrote:
Hi meega,
Well, I don't have workbench yet...
But basically it asks for WorkBench 1.3... white screen, blue coloured disk icon. There is no "Plus" badge anywhere.
Yep, I believe it's an A500. You were quite correct - but I seem to remember a big red LED, on early ones at least...
When you get the Workbench disk, make sure you get the Extras disk that goes with it as well - and enjoy the font editor ;-) I think it's just the two disks that you need (but there are one or two others with some versions). Also, you probably won't need them for a lot of games - they often just use the ROM.
When you get your system disks, COPY THEM and use the copies for everything. Never work with the original disks - make them write-protected and leave them that way. The originals are your source disks, make as many copies as you require for your own needs.
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Thanks meega, I was thinking of doing that actually. Also if my A500 does its reset thingy, will it ruin the disk?
@Tomas and anyone, check my edited post above with the pins. The diagram really didn't turn out, but you get the idea.
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The major risk to a disk is if the machine is actively writing to it (not just reading) when it resets or loses power. That can corrupt the data on the disk, which is why you should never use the original disks as anything other than sources to clone for everyday use. Recovering data from a corrupted disk can be done, with varying degrees of success. Diskdoctor might manage it. Transfer anything you do manage to recover onto a fresh disk. If a disk is corrupt, a reformat will normally allow you to carry on using it. As long as there are no hard errors, it should take and hold a format.
When ejecting a disk, make sure it comes out swiftly and smoothly - sometimes your finger can slip, and the thing gets stuck halfway or pops back in... again there is a risk of physical damage to the floppy surface, but it is quite a slight risk. A good firm press on the button should make the drive eject cleanly. Amiga floppies are amazingly durable, and you should experience few problems. Do beware of hairs trapped in the mechanisms (pet owners), and try to avoid very dusty atmospheres with fans blowing dirt onto the machine.
Ed: as you are in Oz, look out for spiders. :-)
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@meega... hmmm... what to do with my cats? :crazy: We don't have A/C in our house, so fans are the buzz at our place, we have them in each room, gets pretty hot this time of year. I remember using one of them for my old C64 PSU, i think they all(??) have overheating problems, well my two C64 PSU's did anyways.
Man, Amiga disk drives are funny aren't they? They should've put a seperate LED for "write floppy" so we know when to be careful around it. :roll:
Edit: euch! spiders, little baby {bleep}roaches... kitty cats, at least we have no snakes in the city! :-)
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Just don't kill the power, press eject, or reboot when the disk is spinning - if it's working at all then let it finish.
Ed: except of course you are allowed to reboot if you know for a fact that it is only reading and not writing.
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Just some tips:
Last series of A500 have the amber LED for floppy and green for power.
When you open your Amiga again, look for the circuit-printed label (near the expansion RAM header). There you will see the model of the motherboard.
It must says some like:
" B52/Rock Lobster (yeah, is the song from B52'S)
the initials from the crew who made the board
A500 REV. X.xx ( <- expect for 6 or 6A here)"
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For the rebooting issue: with the Amiga opened and not powered on, look for the keyboard header, see if it is properly connected and even further, if the cables are not loosing or peeled. If so, insulate them (one by one).
The keyboard "cpu" is in the keyboard board. If a problem arise in the unit, the capslock LED will blink a number of times.
If apparently everything is OK, close the Amiga case and go for the next, who is...
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The PSU
Whit it disconnected from the mains and from the Amiga itself, open the brick (four phillips screws). You'll not zapped or anything, just be sure to await half an hour after disconnected from the mains.
Check for bulking or leaking capacitors. If you spot one, swap it for an identical unit (the values are printed in the capacitor itself).
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Hope it helps!
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Have you tried running the 500 WITHOUT the keyboard plugged in? (The actual thing you type on, not the computer itself!) Yes you can run the Amiga without the keyboard plugged in. Test to see if it does it's reboot thing... You can buy a keyboard for CHEAP, Just bought one NEW for $10 last month.
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@TjLaZer
hmmm, where did you get it NEW? I'm interested..
I also think he should disconnect the keyboard.
By isolating the keyboard, I mean putting some paper or plastic between keyboard controller and metal shield edge underneath it.
Have a look at it by (easily) removing the 512Kb cover on bottom of Amiga 500, you don't have to unscrew anything for that.
You'll see plastic insulator, make it thicker.
PS. orange is my nick ;-)
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Where else, eBay! They are on there all the time.
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Hi all... sorry @ orange for nick mix up. I just saw "Defender of Faith" and automatically took it for your nick for some odd reason.
Anyways, I'm going to crack open the A500 unit again, and see what the go is.
I'll try the "no keyboard" trick too, and PSU after 1/2 hour of off time. Only problem is that sometimes it won't play up as it should (like last time) so I'll have to check back a few times to see if everything definately is ok. I'll try gently pushing a few chips again too.
Ebay is one of my sources for stuff too TjLaZer, I saw an A520 modulator, new in the box and plastic wrapping! :-o
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@ rkauer
It is written on the mobo this:
B52 / ROCK LOBSTER
GRR/I3P/GUAY/FISH
RVW/VFA/DCA
HJM/CJW/TC/SMK
GET/LLK
A500 REV 5
btw, what is a keyboard header? Is it the plug? (sbsolute newbie here.)
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Header = pins sticking up from PCB.
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So I've checked the keyboard header... seems fine. The wires are ok too... I might put more insulation on under the keyboard pcb someday.
So, one question about the "flashing" Caps Lock key... does it mean it really COULD be the keyboard being the problem? It flashes constantly, no real pattern to it, just on-off-on-off really quickly.
I tried disconnecting the keyboard, and it hasn't reset itself in a while. I tried plugging it back in, and it reset itself constantly at 1 second intervals. Unplugged it again.. nothing. Plugged in again, didn't seem to reset again either.. so I'm thinking probably a broke keyboard. There is a cheap keyboard or two on ebay... should I give it a shot?
Circlip.
ED: meega, I found a little yellow sticker that fell out when I opened the A500 up again. it said "A500 P" and then a serial number. What's the difference between an A500 and A500+ ?
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er, I think you really should NOT (un)plug keyboard while Amiga is ON, you could damage something.
IIRC the flashing capslock usually is an error code: number of blinks indicate the type of problem (for eg. two lines are short).
But not in this case, if its flashing very quickly.
If you got time and patience, its worth opening the keyboard (all those tiny screws) and checking if something like cocacola has damaged it.
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Just remembered - I once had an A500 (a very long time ago) that had the same problem.
It took me quite a time to find the cause.
The problem ended up being a dying Denise. Once replaced, it was rock solid.
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oh, didn't realise I had a reply!
Well, I switched it off between plugging/unplugging, just thought it was a good idea.
There seems to be nothing spilled on the keyboard... I still see no sort of "pattern" to the Caps Lock key led "flashing". It just flashes continuously, that's all.
I edited my last post (on page two) but I'll put it again here.
@meega and all, I found a little yellow sticker that fell off the pcb or somewhere, and it said "A500 P", could this mean an A500+ ? What are the differences between the two?
EDIT: DrDekker... is there a way I can test the Denise chip with a multimeter, and how to do this? I could spring for a Denise next week.
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As far as I know there isn't any means of testing it, but I found out it was the problem by pressing down on the chip when the A500 was switched on and watched out for the reboots. Sometimes the Amiga would reboot and other times it would stay on for ages. I then thought it was just a bad connection, but the problem didn't go away until I replaced the Denise. The original chip must have had a dodgy leg or something. It's worth a ago replacing the Denise as she's a pretty inexpensive old girl. :-D
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circlip wrote:
ED: meega, I found a little yellow sticker that fell out when I opened the A500 up again. it said "A500 P" and then a serial number. What's the difference between an A500 and A500+ ?
The ROMS, the custom chips, and the keyboard itself. That's about it. It allows more chip RAM (1MB standard, and another 1MB can go in the trapdoor), and offers some more video output modes from the Enhanced Chip Set (ECS). Does the A500 have a battery-backed real-time clock as standard? A500+ does. It also uses Kickstart/Workbench 2 (ROM and disks), and is mostly backward compatible for software - especially if the programmers actually followed the rules.
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Another Aussie, and a Sydney sider too :-D
If you can spring for another 500, it might be worth grabbing a working one and experimenting on this one - they're usually not too expensive on eBay. You can never have too many Amiga's :-P
Send me a message sometime if you need stuff, I may be able to help, I've still got my A500 since new in the 80's :lol:
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Is that it in your avatar?
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Meega, we were right before, it's an A500, not plus. Don't know what that sticker was about.. it had A500 and a serial number on it.
DrDekker, yah.. Denise is a cheap one on ebay, she looks like a good purchase.
Darklight! How are you mate? I might actually be moving to Briz next year... but hopefully I can stay here. My mum actually said "Well, what do we do with your Amiga? We might not be able to bring it with us." Even if I toss the monitor.. my Amiga will come along, I'm NOT about to leave it behind! Even if it has to sit on my lap for the trip up!
Money is a bit tight for me atm, so even if I have to get stuff piece-by-piece, like I'm doing, it's the only way for now. I saw an Amiga in Vic for about 60 bucks (excl shipping, PSU, monitor, cables (but I've already got those)) and I just can't do it. Next year maybe when I have some cash, but not now, and I'm impatient to really start using it.
I pretty much got the whole lot "as-is" for 30 bucks, which was a steal, buying each piece (A520 Mod, PSU, two joysticks, monitor) would've been painful, some ppl on ebay are selling each thing seperated.
Well next week or the week after, I'll try Denise. See how she likes her new home. ;-)
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@ circlip
I can totally sympathise with that - I've spent far too long as a student :lol:
Don't move to Brisbane - I guess it's alright though - as long as it's not Melbourne, it's always raining down there anyway :-D I'm in Western Sydney (out near "Penriff"), and there's not many people around these days that have anything to do with Amiga stuff. I know there used to be Amiga User Groups, but I don't know whether they still do anything.
You might want to occasionally check out 'Weekend Shopper' in the Saturday Telegraph - I've seen A500's for $10 in there a few times. None for a while, but you never know. Other than that, the Salvos are always good :-)
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Darklight,
Yeah.. I love Sydney. Brisbane isn't too bad though, but not much to do there. We got all the shops, pubs, clubs, everything here, and our George street is bigger than Brizzy's Queen street mall. I don't know how they do with such a small strip of "city".
Well I'm out on the East Hills train line, (yeah the one with the stops for the airport). Not bad out here, but boring. I've been skulking salvo's and other op-shops, trying to see if anything turns up. I once bought a Playstation 1 for 3 dollars, and it wouldn't load a disc, so I got a guide online to adjust the trimpots and it worked!! I've got my sources for games for it too, which is cool.
I'll have to check the Saturday Telegraph paper then, it's interesting some of the things you find, huh? Another man's trash is another man's treasure. :-)
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The blinking Caps Lock LED gives it away. You have a flaky power supply. I've been through this before. The A500's power supply was weak to begin with, and now is really showing its age.
What I did was to measure the voltages on each of the pins when it was plugged in and on, then traced each pin to its respective wire. I then cut the wire from the power supply going to the A500, and spliced it into a PC power supply. That is what I did to resolve the blinking caps lock LED and intermittent resets.
Bear in mind that a bad power supply can cause other damage to your Amiga, so it really is in your best interest to get something beefier.
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Thanks guys...
I've bought a keyboard and Denise chip, and will test these out.
DigitalQ, if these don't work, I'll spring for a PSU.
Anyone have any tips on removing and rplacing a chip? I figure it's pretty nasty to attack it with a screwdriver, right? ;-)
Circlip
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Hi everyone.
I have tried changing the Denise chip, and also replacing the keyboard. Both were tested 100% working before sold to me.
I think it might be the PSU giving me problems, as someone mentioned earlier. I'll try that next.
Thanks,
Circlip
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circlip wrote:
I have tried changing the Denise chip, and also replacing the keyboard. Both were tested 100% working before sold to me.
I think it might be the PSU giving me problems, as someone mentioned earlier. I'll try that next.
Thanks, Circlip
Like I said before, those originals PSUs are prone to fault. Use a peecee AT or ATX instead.
Don't know how?
It's easy: look at Amiga Hacking Zone (http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_Power_supplies/amiga_power_supplies.html), by Ian Stedman.
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Hi,
I got a few unused A500 psu`s if you want to pick 1 up fell free too.
i`m in sydney(2207)
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Hi guys, thanks for all the help. It was just a faulty PSU. Everything is working ok now, and I have workbench 1.3 now too.
Thanks to the Amigan friends in Sydney, you guys rock!