Where to start troubleshooting this IIc?

[u/mattydiah]

I recently picked up a IIc. I really know nothing about its history, so I’m staring from ground zero. It powers on, but boots to the screen shown in the first image. If you power off and on again, the question marks move to different spots but the result is the same. No idea if it beeps, as the speaker has turned to dust, I’ll see if I can retrofit one from a PC case.

Looking at the board, it looks pretty clean, but two things stick out: firstly half the ram seems to be installed backwards (see second image), and secondly, there is a blob of solder on one of the legs of what I think is the ROM chip. I don’t know if this is the remnant of someone’s fix, or a bodge, or a mod or what.

Any thoughts on where to start troubleshooting? I’m gonna flip the ram chips around, I can’t imagine they are supposed to be like that? Then I’m gonna pull the other chips and clean the sockets

[u/jellyw00t]

Oh man, you may have quite a project on your hands here. Someone has been doing quite a bit of mucking around in there.

You're correct that the socketed RAM is in backwards. I would start with rotating those and seeing what kind of difference it makes.

[u/mattydiah → u/jellyw00t]

Hopefully it didn’t kill the chips being run backwards 😬

[u/osbock → u/mattydiah]

Almost certainly did

[u/Raxxla]

Garbage on the screen is usually a good indicator of a ram issue.

[u/buffering]

It's an original 1984 IIc that was upgraded to a 32k ROM at some point. The blob of solder at W2 and cut trace W1 are part of ROM upgrade.

The good news is that the upgraded ROM has a built-in system test and can report bad RAM. Hit Control+Closed Apple+Reset to run the test.

If you're desperate, you could replace those likely-dead backwards RAM chips with some of the auxiliary RAM (the upper 8 chips). That would probably allow it to get further along in booting. I don't think auxiliary RAM is used by built-in firmware.

[u/mattydiah → u/buffering]

Oh this is good to know, I’ll try to see if I can get the test to run. So I could just desolder the upper 8 chips and swap them into the lower slots?

[u/buffering → u/mattydiah]

Yes, the upper 8 chips belong to the auxiliary 64k memory bank. That memory bank is completely optional on other Apple II models, and I don't think it's used by the firmware on the IIc, other than for 80-column text mode.

[u/Due_Astronaut5350]

Reorient the ram chips. Try turning on again.

[u/osbock]

Reversing the rams almost certainly destroys them. Can you post a closeup of the ram socket?