UPDATE 2: ... and now I've gotten the 16K RAM card to work as well! Things are apparently moving forward quickly today!
Could be reseating some ICs, the IDC cable, the card itself in the slot or something else.. In any case it appears to work now and I've even gotten ADTpro to transfer with ProDOS, so that's one HUGE leap forward! I am however confused about some details regarding ADTpro, but think I'll post about that separately.
UPDATE 1: I just discovered that the cassette IN actually works! (after posting my message below).
The problem appears to be with my 16K RAM card (a Microsoft clone), so when I removed it (from slot #0), put the RAM chip back in the E4 socket on the motherboard (where the RAM-card ribbon cable previously went) I successfully transferred eDOS via ADTpro! What's even better -with a working DOS disk I tried reading several of the previously unreadable floppies and the ones I've tested gave me a directory listing! That's great because I have many of my own created files there, which I hope to be able to transfer over to my Mac.
But.... I believe I need 64K in order to be able to use ADTpro for transferring files/disks, so does anyone have any suggestions for how to go about troubleshooting/testing the 16K RAM card?
Oh, ASCII-express file transfers still refuses to work, so ADTpro appears the way to go (I've already spent too much time fiddling with this).
I'm having trouble transferring software (Asciiexpress or ADTpro (audio) from my Mac) to my II+ cassette in and am starting to think there might be some hardware issues. I found this handy chart at AppleII-box.de which tells me that two ICs (741 and a 74LS74) near the game port handles this stuff. So I've swapped those with other ICs.
I did notice something strange when doing a "SAVE" (from the Applesoft prompt) -that with a particular type of 74LS74; namely one labelled
.... a "thumping" or "clicking" sound would be heard. I had two of them (both labelled the same) and they both performed the same. Swapping it out with a different type of 74LS74 removed that clicking (I tried 3 other regular and clearly brand name labelled chips) and they all worked fine. That "PC" designation is something I've never heard about, and there's no brand labelling either (Fujitsu has a logo as far as I remember, so this seems to be something else -a fake or something perhaps?).
Anyway, that out of the way, and also checking the jacks and cables for both the cassette IN and OUT ports (using a multimeter), trying different volume levels, what else can I check?
Back to the actual problems I'm getting: with ASCII express I've never gotten anything to work. With ADTpro (2.0.2 on a Mac) I've been able to transfer both ProDOS and DOS, but only the first parts (the good thing is that obviously something intelligible is received, as the title text for ProDOS at least is fully readable), but running it doesn't work -instead of starting up I'm returned to the machine code prompt with some code, surely indicating some errors.