lowen
Veteran Member
well found a short near one of the PALS. Seems like the 12 ohm reading is normal. Still getting bughlt no68k even after swapping the CPU. Reseating all socketed chips. Cleaned edge connector etc. So no one out there has seen this problem before. Please help I really need it on this one.
Check for a shorted capacitor, possibly one or both of the electrolytics (C54 and C55, both 100 microfarads 16V). These might possibly be tantalum caps, in which case those are known to short out in this age range. Typically they'll show some physical fault, though. The PALs being U6, U36, U40, and U48: three of those are near C54 and C55.
Also, while it would be rare for them to fail shorted, it could possibly be one of the 0.1uF bypass caps scattered all over the board. But I'd start with the two electrolytics.