Re: Apple IIgs error on start-up (any ideas)- Fatal System Error - 0911

[Rubywand <rubywand@swbell.net>]

Keith writes ...
> 
> I have a IIgs that comes up with "Fatal System Error - 0911" when you
> switch it on? Any ideas on what this error message means, so I can see if I
> can fix it??
>
 ....

     Fatal System Error 0911 indicates that you are experiencing an
Apple Desktop Bus (ADB) Controller "can't sync" problem. Usually, this
indicates an ADB Controller IC malfunction. (I seem to recall that the
error had a different number on ROM-00 machines-- something like 0400--
not sure. Upgrading to the 01
ROM changed the number to 0911.)

     Many early GS's came with an ADB IC which malfunctions over a
narrow range of relatively low temperatures. Rooms are normally cooler
during summer; so, this is when the error pops up most frequently.

    '0911 bombs can occur 'any time' but they usually happen at startup
and when doing OpenApple-CTRL-ESC accesses to the Desk Accessories
(CDA's, Control Panel, ...) menu. As the machine warms up, '0911 crashes
tend to become less likely.

     There is no 100% fix except to replace the temp sensitive ADB IC.
Unfortunately, it is soldered to the motherboard and, besides,
known-good replacements are difficult to find. Originally, users who
noticed the problem in time got a fix by getting a motherboard swap from
Apple. (As fate would have it, the GS was released in the fall when
rooms were generally warmer. By the time many users knew there was a
problem, their warranties had expired.)

     Since the problem is coolness, a decent cure is to tape a small 12V
panel light bulb to the top of the ADB IC (one of the square IC's near
the right front of the motherboard).

     As to _which_ ADB IC-- there are two, the ADB Controller and the
ADB GLU-- our notes say the ADB Controller; but, we could have easily
misidentified the function back then and the ADB GLU IC 'clicks' better
with memories of the fix. (The ADB GLU IC is a bit larger and easier to
reach.)

Note: The easiest way to identify the temp sensitive IC is to apply the
fix (below) and see if it works. If it does, fine. If not, it is easy to
move the fix to the other IC. For now, my suggestion is to try the ADB
GLU IC first.

     Use duct tape and try to enclose the bulb and IC in a kind of
mini-oven. Run the leads from the bulb to the +12V Fan power pins near
the back left area of the motherboard.

     The idea is to quickly warm up the IC. I used a scheme like this on
our early GS and 0911 bombs dropped from 4-5 per day to 2-3 per week. If
you can safely power the bulb via an external power module (e.g. a
calculator or radio 'AC adapter') so that the bulb can be ON at least a
few minutes before powering up the computer, 0911 bombs might disappear
entirely.



Rubywand