Fixing a Portable M5120; Divide by Zero Error(?)

[theletter0xff]

It chimes, then death chimes.

Sad Mac error code
01000400
0007FFF6

I am stuck. Following http://myoldmac.net/FAQ/SADerror-portable.htm to decode results in ROM test failed, divide by zero. At a guess, there are traces hiding under chips that are bad, or logic chips were zapped by someone trying to power it with a bad battery and the wrong power adapter, but I don't know where to start.

 

[David Cook]

Is this a 5120?

If so, try adding a temporary bodge wire as shown in purple.

There seems to be an electrical noise issue in many 5120 Portables when the sound circuit turns on. It causes the CPU to scramble. The above bodge just keeps the sound circuit on all the time. It is a workaround until the community discovers the true fix.