Hello!
I've moved on to solving problems on my 488 interface. I know that I have at least one failed MC3446 because one leg was disintegrated. The other two are unknown... However, I purchased a pair of MC3446N chips and tried swapping between them... The GPIO diags that Frank referred me to come back even worse with the new chips in place. With the old chips, the drives will light up and seek, but I get weird stuff at the top of the display and disk access is definitely not successful.
I can't seem to find anything definitive. Can anyone tell me if the MC3446 chips are MC3446N or MC3446AP in the original? The schematics just have "MC3446" on them
Apparently the difference is internal termination. Of course, with old parts, it's also entirely possible that both of the "new" chips are bad.
Thanks!
ps- Before you ask, yes, I've tried a number of different 6520s. No difference.
I've moved on to solving problems on my 488 interface. I know that I have at least one failed MC3446 because one leg was disintegrated. The other two are unknown... However, I purchased a pair of MC3446N chips and tried swapping between them... The GPIO diags that Frank referred me to come back even worse with the new chips in place. With the old chips, the drives will light up and seek, but I get weird stuff at the top of the display and disk access is definitely not successful.
I can't seem to find anything definitive. Can anyone tell me if the MC3446 chips are MC3446N or MC3446AP in the original? The schematics just have "MC3446" on them
Apparently the difference is internal termination. Of course, with old parts, it's also entirely possible that both of the "new" chips are bad.
Thanks!
ps- Before you ask, yes, I've tried a number of different 6520s. No difference.