System 11B board problems, now with video!!:)

Nicholas:

The ten flashes indicate "in theory" that there is a problem with ROM U27. The issue is that the self diagnostics are not always accurate, and the problem may not actually be the ROM itself, but associated circuitry, including PIA's.

Battery damage is elusive, because it causes all kinds of unseen problems - and also creates shorts, because the battery "liquid" is conductive. It really requires a stripdown of all parts that were affected by the leakage to remove all possibilities of interference. It can even be a socket issue!

I have a board right now that is giving me 11 flashes at boot up (meaning a "U26" ROM problem), I plan to look at it today. I will let you know what I find.

Chris
 
Hey Chris M and Lindsey!

I'm never going to socket all those PIAs:)

The reason why I'm still trying is that after I changed those SIPs the
situation is somewhat better. Before that, only the +5V LED was on....

The board had 'homemade' SIPs installed before, with only nine píns.

But IF it is U27, does that also account for the huge voltage drop on the board??

Thanks!

Nicholas
 
Any short/partial short can/will compromise voltage to some extent. It can be any chip, any where, really, it can be a compromised gate in a TTL chip, a leaky cap, etc.....any path for electron flow between power and ground.

Still don't think it's your ROMS, see my PM.

Chris
 
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