[Coco] 6821 PIA Chip Bad?

[Arthur Flexser]

I had an almost identical situation years ago with my dad's Commodore-64
that crashed after a few seconds. Its PIA-equivalent chip was very hot,
cooling it with some ice in a plastic bag delayed the machine's crashing,
and swapping the chip with an identical one on the same board changed the
symptoms of the crash.   A new chip cured it.

Art
On Wed, Apr 27, 2011 at 3:38 PM, Steve Batson
<steve at batsonphotography.com>wrote:

> Sounds like something is shorted.
>
>
> Steve Batson
> Batson Photography
> "Today's Special Moments, Tomorrow's Priceless Treasures"
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> On Apr 27, 2011, at 11:30 AM, Eric Keppel <keppel at earthsounds.com> wrote:
>
> > Hi Coco Folk!
> >
> > Well, I purchased another Coco on eBay, and unfortunately, it got lost
> > by the USPS for about a month and then suddenly appeared at my door
> > yesterday.  The delay was caused by the box ripping apart, and the Coco
> > obviously fell out and got caught on a conveyor belt or something.  The
> > case is really beat up now and the power and reset button are missing.
> >
> > Anyway, I powered it up and it wouldn't boot (garbage on the screen,
> > sometimes an orange screen, and once in a while the ECB 1.0 message,
> > missing key presses from some keys).  Even when it would manage to boot,
> > it would always lock up in about 60 seconds or so.
> >
> > I cracked the unbroken warrantee seal (bummer) and opened it up to have
> > a look.  It's an older gray Coco1 with a Rev. E board and 16k.  After
> > checking that all of the various chips were seated well, I noticed that
> > one of the 6821 PIA chips was running VERY hot.  I just about burned my
> > finger on it.  Well, I swapped the two PIAs with one another and it
> > booted right up nicely, but didn't stay up for very long, then that same
> > PIA chip got hot again and the machine locked up.
> >
> > So, I am suspecting that the hot PIA is bad since it got hot regardless
> > of which socket it was in.  In fact, when I put my finger on it, the
> > machine stayed up much longer, presumably because my finger is acting as
> > a heat sink and keeping the chip going a little longer.  This is very
> > unscientific, but my best guess.
> >
> > I see that the chips aren't too expensive, so I was thinking of getting
> > one to replace it unless someone has a better suggestion or sees
> > something I missed.  Am I on the right track?
> >
> > --Eric
> >
> >
> >
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