At power up, sometimes, my europlus shows random stuff on the screen, or vertical bars (with low res graphics). This doesn't stay for long, and re-trying get the machine boot a bit.
In 95% of the cases, I get a black screen, with the "APPLE ][" on top, and a "/" at the first screen, in position 4 (ie: 3 spaces, then the "/").
In a couple of occasions, I got a "+" instead of a "/". I once got a ".". For reference, the ascii codes are 2F, 2B and 2E. It is ALWAYS in first line, column 4.
Lately, I got a couple "APPLE ][" message, immediately replaced by a screen full of "?"
When I press RESET, I generally get the basic prompt, and I can type (keyboards works fine), but pressing RETURN whill hang.
Sometimes, pressing RESET will drop me in the monitor, sometimes with a assembly listing. In those cases, when I press RESET, the listing continues. Sometimes the listing is half a line, sometimes several pages. Listing is often garbled in a very particular way (some complete lines are draw at the wrong location). It always starts a 0000.
Machine is an Apple ][ europlus.
Motherboard: 820-001-07 (c) Aple 1979. There is a hand written sticker on the board that says "8043". All ICs are in sockets.
RAM: 48K originally, 1 row was Apple branded, not the others. I swapped the RAM around to make sure it isn't a RAM problem. I removed all the RAM but the first row, to have 16K.
Removed all the cards (diskII + super serial).
I removed, cleaned with IPA and contact cleaner, and reseated all the ICs in row C and higher. ROM F0 seems quite different from the others, with very dirty pins, and I feel one is flimsy as hell. I'd rather not remove and plug it again if I can avoid.
Nothing I did had any sort of change to the issue.
I bought a MiniPro with which I will use when delivered to check the various 74xx circuits. My understanding it that I will not be able to test the ROMs or the RAM with it.
Does any of this rings a bell? The errors are not *always* exactly the same, but *very* close. I feel it could be a bad ROM (may be wrong, but if RAM, I would expect the error to be more deadly is systematic, or more random).
Thanks in advance!