Fixing a Portable; Divide by Zero Error(?)

theletter0xff

New Tinkerer
Jan 5, 2024
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It chimes, then death chimes.

DivdeZero.jpg


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.