Re: Fatal error 0911 and GS self-test

[rubywand@aol.com]

In article <59825e$h3i@news.stolaf.edu>, Peter F Handel
<handel@stolaf.edu> writes:

>
>Computers can never be too cold :)  There's refrigerants to really freeze
>your CPU to make it run much faster.
>
>

     In the case of some ADB Controller IC's used in early GS's, 65
degrees F may be "too cold".

    We are, really, dealing with malfunctioning over a range of
temperatures. For example, the IC may function fine at 55 degrees and
below and at 80 degrees and above. Since the IC can start at a temp below
its peak 'glitch range' and warm up into the range,  ADB IC bombs can
appear to be a result of "over-heating".

     Many users find the ADB IC "over-heating" problem a very frustrating
one to cure. Naturally, because steps which cool the computer may actually
increase the frequency of 0911 crashes. One could, 'with luck', even
stabilize the IC temp squarely in the middle of its glitching range! We
found that adding a System Saver GS had this effect. Similarly, after
warm-up, spraying the IC with coolant increased the chance of bombs. 

     It seemed like a good idea to help warm up the IC as quickly as
possible to get it past the glitch range of temperatures and keep it
there. So; we taped a small 12V panel light bulb to the IC with duct tape
enclosing the bulb and IC to form a mini-oven. (The bulb was powered using
the 12V fan power pins located near the left back of the motherboard.)

     The fix could hardly have worked better! Before, we could count on a
few 0911 bombs each day. After the fix, bombs dropped to near zero per
week.

     Perhaps some ADB IC's do bomb at higher temps (e.g. 130 degrees F,
etc.).  In these situations, the above fix will not work. For the majority
of Woz machines plagued by 0911 crashes, the bulb fix should just about
eliminate the problem.
 

Rubywand