Amiga 500 intermittently reboots for no reason!

[circlip]

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.

[weirdami]

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.

[TjLaZer]

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...

[zipper]

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.

[circlip]

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.

[orange]

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.

[circlip]

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

[weirdami]

@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. :-)

[circlip]

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.

[TjLaZer]

I would unplug the keyboard and use it for a while to see if it is indeed the KB that is causing the reboots...

[circlip]

@ 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.

[Jope]

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.

[weirdami]

@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.

[JLPedro]

   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.

[circlip]

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.