How to troubleshoot your defective 386/486 motherboard with an oscilloscope

[Rasz]

I've listened to about 1 hour of that wireless guy's life as an engineer.  Absolutely fascinating.  I started watching while lying down in bed thinking it would be good material to fall asleep with, but on the contrary, it kept me up.

Computer History Museums Oral History series is pretty great.

Sounds like the missing components is a result of muntzing, which occurs for 2 main reasons as noted in that URL you shared: 1) cost reduction, and 2) excess components as causing more harm than good.

and 3/ being chabuduo and plain fraud. There is design optimization, and there is Chinese removal of fuses because $.02 more profit.

I mention the electrical wiskers theory because I did notice a small blob bridging two pins of the 482 chip...........If it acts up again, I'll have a look at the SRAM traces.

482 doesnt connect to cache, I cant imagine situation where computer with faulty 482 works without cache, but generates errors with cache on. The only common link is processor data bus, and short here would screw boot every time. Better do some percussive debugging on that board, try touching cache sockets while running etc.

[feipoa]

Yes, I know - I had the same sentiment as you concerning the 482 and would have been more convinced if it had been the 481.  But the order of events is too coincidental. Keep in mind, though, that I also cleared out anything which looked suspect between all leads of the 206, 482, 481, and AM386DX.  I did not swap the cache around between "cleaning".    That is, motherboard not working with L2, symptoms are repeatable from day 1 to day 2; while touching nothing else, I "cleaned" the SMD IC's; powered back up, no L2 errors. 

I'm not saying with absolute certainty that I've isolated the problem, but unless the symptoms reemerge, I'll be following the advice of this popular adage "if it ain't broke, don't fix it".   Of course, I will continue to test the system, move it around, press here and there, etc.  I intend to test an SXL2-50 at 55 MHz, a DRx2-66, and an IBM Blue Lightning DLC3 at 100 and 110 MHz.