Hi Folks,
I have recently aquired a trip back into my childhood and have a lovely Apple II Europlus with 9" B&W monitor and Disk II controller with drive.
Everything seems to work ok and as expected, until I plug any expansion card into any of the slots. The Disk II controller can plug into any slot, and all works as expected. However, if I plug my A2DVI card or a 16k memory expansion card (In to slot 0), then the computer just doesn't boot. There is no beep, and the disk drive doesn't spin. In addition the screen just displays all white squares.
I have a spare non-working Apple II europlus motherboard, if I need to try swapping IC's out to troublshoot. Does anyone have any clues as to what the issue might be related to.
Thanks
I'd start with the 8T97 chips which are near the expansion slots. H1-H3. Look for 74LS367 chips installed there instead of the proper 8T97. 74LS267 chips are functionally compatible except they aren't able to drive as high of loads as fast as a real 8T97. They will often work in a lightly loaded machine but will start to behaveweirdly or fail if you add more cards.
One source of them is here:
https://www.reactivemicro.com/product/8t97/
You can also find them through Amazon, eBay or Aliexpress (watch out for fakes or re-marked 74LS367 or even 74C367).
Thanks, I'll check that out and feedback.
The 74LS138 Line Decoder at H2 is a plausible candidate.
In this previous thread, user tony359 had a Europlus with two bad 74LS138 Line Decoders. The one at H2 can cause a conflict between any two of the cards you listed, so it's the best candidate. The Line Decoder at H12 might cause conflicts between the Disk II and A2DVI cards, but it wouldn't affect a 16K card.
If replacing H2 resolves the conflict between Disk II and 16K card, but doesn't fix the conflict between Dist II and A2DVI then the Line Decoder at H12 is probably bad. Maybe both H2 and H12 are bad...that's what happened in tony359's case!
Thanks, I'll try swapping those out and feedback.