Re: button 0 is stuck on IIgs

[rubywand@aol.com (RUBYWAND)]

In article <55gduh$o08@europa.frii.com>, shack@deimos.frii.com (Randy
Shackelford) writes:

>
>I located something I thought I'd never find up in Denver today, a
signature
>edition IIgs with ROM 0 and the original VGC. I bought it and brought it
home
>but when I tried running the diagnostics, it turns out that button 0 is
stuck
>in the pressed state. There's no joystick attached, and it's not the
keyboard
>either since it does the same thing with the original and a standard
keyboard
>II I tried on it. Any ideas? I could always swap the board with one of my

>spares but I'd prefer not to take out the original plus it'd mean
swapping
>ROM and VGC chips.


     What happens if nothing but the monitor and boot drive (i.e. no other
cables of any kind)  are plugged in?

     The idea of checking for a short at the 9-pin game port sounds like a
good try. Pin 7 (B0) shorted to Pin 2 (+5) would look like a Button 0
press.

     Something else to check is the ADB Controller IC. It's toward the
front-Right of the motherboard. The ADB chip was/is a problem on quite a
few Woz edition machines. You may be able to tell whether someone
attempted to replace the IC and messed up. (Or, there may be some sliver
of metal, spilled Coke residue, etc. shorting ADB chip leads.)


     



Rubywand