Eric Rucker

Just trying to narrow down where I should troubleshoot... went to fire up my //c this morning (worked yesterday just fine), and it didn't boot - no beep, and every other row of the screen was a white bar. I BELIEVE that meansthe video section is up, the CPU section is down?

The //c is a ROM 0, with a Z-RAM II with 768k RAM.

Attempted making sure the CPU was well-seated in the Z-RAM II, no change.

Reseated the Z-RAM II, no change.

Removed the Z-RAM II entirely, no change (but I didn't expect one).

Installed the CPU, and an MMU I had lying around (Z-RAM II kinda captures the MMU installed in it permanently), no change.

Reseated the ROM, IOU, and chargen (I know the chargen has nothing to do with it, but I figured reseat it anyway), no change.

Where should I look from here?

Thanks,
Eric Rucker

Michael J. Mahon

Eric Rucker <bhtooefr@gmail.com> wrote:
> Just trying to narrow down where I should troubleshoot... went to fire up
> my //c this morning (worked yesterday just fine), and it didn't boot - no
> beep, and every other row of the screen was a white bar. I BELIEVE that
> means the video section is up, the CPU section is down?
>
> The //c is a ROM 0, with a Z-RAM II with 768k RAM.
>
> Attempted making sure the CPU was well-seated in the Z-RAM II, no change.
>
> Reseated the Z-RAM II, no change.
>
> Removed the Z-RAM II entirely, no change (but I didn't expect one).
>
> Installed the CPU, and an MMU I had lying around (Z-RAM II kinda captures
> the MMU installed in it permanently), no change.
>
> Reseated the ROM, IOU, and chargen (I know the chargen has nothing to do
> with it, but I figured reseat it anyway), no change.
>
> Where should I look from here?
>
> Thanks,
> Eric Rucker

Memory.

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon

Eric Rucker

There a good way to tell which chip is bad, given that it won't come up to the self test, or should I remove one, install a socket, install a fresh chip in there, and test, and do that until all of the MRD chips are replaced?I hate working on //c motherboards, easy to lift a trace...

Michael J. Mahon

Eric Rucker <bhtooefr@gmail.com> wrote:
> There a good way to tell which chip is bad, given that it won't come up
> to the self test, or should I remove one, install a socket, install a
> fresh chip in there, and test, and do that until all of the MRD chips are
> replaced? I hate working on //c motherboards, easy to lift a trace...

You can try piggybacking a known-good chip on each DRAM chip. This doesn't
work for all failures, but it works for many, and can save a lot of work
(and risk).

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon

Bill Garber

"Michael J. Mahon" <mjmahon@aol.com> wrote in message
news:925903782347773742.023602mjmahon-aol.com@news.giganews.com...
> Eric Rucker <bhtooefr@gmail.com> wrote:
>> There a good way to tell which chip is bad, given that it won't
>> come up to the self test, or should I remove one, install a socket,
>> install a fresh chip in there, and test, and do that until all of
>> the MRD chips are replaced? I hate working on //c motherboards,
>> easy to lift a trace...
>
> You can try piggybacking a known-good chip on each DRAM chip.
> This doesn't work for all failures, but it works for many, and can save
> a lot of work (and risk).

I tested my IIc's ram that way when I needed to, and it worked every time.

The last time, I actually just soldered the new chip onto the top of the old,
pin to pin, being careful of course, and it works to this day. If I recall, it
was well over 3 years ago.

Bill

Michael Black

On Sun, 8 Jan 2012, Michael J. Mahon wrote:

> Eric Rucker <bhtooefr@gmail.com> wrote:
>> There a good way to tell which chip is bad, given that it won't come up
>> to the self test, or should I remove one, install a socket, install a
>> fresh chip in there, and test, and do that until all of the MRD chips are
>> replaced? I hate working on //c motherboards, easy to lift a trace...
>
> You can try piggybacking a known-good chip on each DRAM chip. This doesn't
> work for all failures, but it works for many, and can save a lot of work
> (and risk).
>
I once found the bad ram in my Atari ST simply by checking the touching
each of them. One was noticeably warmer, changing it fixed that problem.

I know the failure was overvoltage, the power supply had a problem before
this RAM issue came along. I don't suppose others would be so lucky as to
have the same sort of failure.

Michael