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From: Ian McCall on 28 Jun 2010 10:55
OK - looks like my breadbox-style C64 has died. I power it up, and nine
times out of ten I get gibberish characters on the screem. Few things
load, either tape or disk. It won't read from the MMC64 I've been using
for ages either, and that also has gibberish characters on the menu.

Sound likely to be a RAM error to anyone else? Any checks that can be
done, and is the prognosis terminal? Am guessing yes, but you never
know.


Cheers,
Ian

From: Clocky on 28 Jun 2010 11:05
Ian McCall wrote:
> OK - looks like my breadbox-style C64 has died. I power it up, and
> nine times out of ten I get gibberish characters on the screem. Few
> things load, either tape or disk. It won't read from the MMC64 I've
> been using for ages either, and that also has gibberish characters on
> the menu.
> Sound likely to be a RAM error to anyone else? Any checks that can be
> done, and is the prognosis terminal? Am guessing yes, but you never
> know.
>

Nothing is terminal ;-)

It does sound like a RAM problem it it is intermittent, but have you
reseated the VIC-II and any other socketed chips? You might also want to
check the power supply as voltage ripple can take out the RAM before
anything else.

A shorted memory chip will get very hot when compared to the other chips so
do a feel test to see if any are hotter then the others. If any are cooler
then the others it may have gone open circuit, and an easy test would be to
clip a spare DRAM chip over the suspect faulty one piggyback style and see
if it corrects the problem.



From: Dombo on 28 Jun 2010 13:45
Clocky schreef:
> Ian McCall wrote:
>> OK - looks like my breadbox-style C64 has died. I power it up, and
>> nine times out of ten I get gibberish characters on the screem. Few
>> things load, either tape or disk. It won't read from the MMC64 I've
>> been using for ages either, and that also has gibberish characters on
>> the menu.
>> Sound likely to be a RAM error to anyone else? Any checks that can be
>> done, and is the prognosis terminal? Am guessing yes, but you never
>> know.
>>
>
> Nothing is terminal ;-)
>
> It does sound like a RAM problem it it is intermittent, but have you
> reseated the VIC-II and any other socketed chips? You might also want to
> check the power supply as voltage ripple can take out the RAM before
> anything else.

Based on my experience problems with RAM chips are either bit failures
(symptoms: some characters are might wrong, crashes with some or all
programs) or a shorted chip (resulting in a dead C64). Reseating chips
and checking the power supply are good tips, which I would try first
before looking further.

> A shorted memory chip will get very hot when compared to the other chips so
> do a feel test to see if any are hotter then the others.

If it is shorted chip (getting very hot) I wouldn't expect intermittent
symptoms but rather a totally dead C64.

> If any are cooler then the others it may have gone open circuit,and an easy test would be to
> clip a spare DRAM chip over the suspect faulty one piggyback style and see
> if it corrects the problem.

If does correct the problem it does tell that the RAM chip has gone
circuit (have never sen this happen), however if it doesn't correct the
problem you can't say anything about the state of the RAM chip; it might
be good or it might be bad.
From: Sam on 28 Jun 2010 17:37
On 28 jun, 16:55, Ian McCall <i...(a)eruvia.org> wrote:
> OK - looks like my breadbox-style C64 has died. I power it up, and nine
> times out of ten I get gibberish characters on the screem. Few things
> load, either tape or disk. It won't read from the MMC64 I've been using
> for ages either, and that also has gibberish characters on the menu.
>
> Sound likely to be a RAM error to anyone else? Any checks that can be
> done, and is the prognosis terminal? Am guessing yes, but you never
> know.
>
> Cheers,
> Ian

I think it's the PLA who is bad. I've seen this symptoms before.

SAM
From: Andreas Kohlbach on 28 Jun 2010 21:34
Ian McCall wrote on 28. June 2010:
>
> OK - looks like my breadbox-style C64 has died. I power it up, and
> nine times out of ten I get gibberish characters on the screem.

Wow. I had this with my first C64 which I bought October 1984 (yes, I was
late). I was excited to start it. And that really ruined that special
day. :-(

Similar for the Amiga 500 I bought a few years later. It worked but
certain hardware hungry demos not (main reason I bought it :-). I
returned both and the next would work.
--
Andreas
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