Hi! I recently got an Enhanced IIe from someone who was getting rid of it and I've been trying to coax it back to life. I have had a II+ for years and, except for a power supply failure, it's been rock solid.
Anyway. the IIe had a blown power supply, so I tempoararily swapped in good (ReActiveMicro) one from my old Apple II+. On first powerup I get a blank screen with no beep. Turn it off and back on and I get random vertical lines. I say random because I can turn it off and on again and get another variation on those lines. Here's a picture:
Here is what I have tried so far:
1. Pulled 65C02 (338-6503) out of IIe and installed in II+. The CPU works in the II+
2. Swapped the DM74S02N at B8 with a new SN64S02N
3. Swapped the 74F109PC at C1 with a new SN74109N
4. Swapped the 74LS125APC at E1 with a new SN74LS125AN
5 Tried pulling CPU totally and seeing what happens. Still get the same random vertical lines!
Any ideas as to what's going on? I'm baffled!
Here's a picture of the board:
Leave the machine on for 5 minutes or so and then feel the top of each IC. If any of them are much hotter than the rest - replace.
I had a case where I had to swap out the SN74LS245N (LS245) to fix the vertical lines issue. I note it is also present on your board in position B2.
Thanks for the tip! I happened to have a spare LS245 to swap in and it's doing the same thing, sadly. Hopefully that LS245 isn't bad as well.
I let it run for a while and nothing really stood out heat wise other than that LS245 and it wasn't uncomfortably warm.
I am able to check and verify the video rom with a chip programmer, but I can't check the CD and EF roms as I don't think it can read those types of chips.
Could be worthwhile to take the 6502 from your II+ and give it a spin in the IIe ?
Otherwise - might be worth getting an IIe enhancement kit -these are not too expensive and usually ship with all the ROMS and a new CPU. I ordered a kit from Ebay (in Europe) or Reactive Micro might be an option in the US: https://www.reactivemicro.com/product/iie-enhancement-kit/
Keep us posted - if you solve the puzzle, I'm sure it will be useful to others in the community.
Last idea - try and chip swap the RAM. Usually the RAM from an 80 column card can be use don the board. I see yours is socketed so should not be too much of a hassle.
RAM kits available on Ebay as well - there are a few variants that are compatible.
Ok, just tried swapping in some M3764-15RS for the M6665a RAM chips on the board. I did get a different output: solid, evenly spaced white bars. They never randomized.
ramswapdisplay.jpg
(ignore the pink color in the bottom right, the refresh rate was messing with the camera)
I also tried swapping out the 6502 from the II+ to no effect.
With or without the CPU and with the swapped RAM I got that display.
I put the old RAM back in and I'm back to the randomly generated bars.
I guess it would be worth it to pick up the enhancement kit roms, if nothing else, and see what happens!
I think the MMU and the IOU chips are toast. I tried swapping in known good roms and another known good CPU and still get the same thing. D'oh!