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Do you have an oscilloscope? You can try to find out if the signal is inverted and / or multiplexed correctly, or if some chip is marginal and doesn't output the correct singal level on one of its pins.

I cannot contribute much (don't even have a QL) but I recently found out about the SuperIO and thought about how it could be used with or for an old computer. I hope you can finish the project in some way or another

The garbage characters have more of the other characters though... does it still run through the diagnostics? It could be that you have a broken trace, cracked solder joint or bad socket. Does the pattern change when you flex the board on different spots or press on the socketed chips...

Char ROM would not display complete characters as seen in the post with all the pictures. I would say something wrong with the RAM or the supporting logic chips, as most of the computer seems to work. Since VIC, PLA and CIA are tested good, my guess is something on the VA14/VA15 line or a RAM...

If you check the C128 diagnostic instructions PDF (https://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c128/servicemanuals/index.html), page 3-4 has a list of symptoms, yours could be letter I., signal on VA14? You could find a closer description to your fault or measure the signals...

Can you burn a diagnostic cart and post the results: https://www.zimmers.net/anonftp/pub/cbm/firmware/misc/c128diag/index.html

Replacing the LM733 didn't change anything. There's still some weird noisy output on TP5. I have no idea what could cause this. Any ideas are welcome

Good quality flux and braid make all the difference. Cheap braid is mostly useless on anything but single sided boards. For the bent legs, I use flat blade tweezers (the rounded one from the iFixit toolkit) to lift them up while I melt the solder with the iron. +1 for getting a desoldering...

Yes, they work with anything 286 and newer that puts out POST codes. I had one in a recent Asus mainboard (6th gen Intel) because I was too lazy to connect anything and wanted to check if it lives. Other "fun" PCI cards: - SCSI controllers with things like tape drives, Jaz, scanners - PCMCIA...

Any details here? What's an example for a light solvent and how much do you dilute it? How do you apply it?

Like mentioned, I used FlashFloppy (https://github.com/keirf/flashfloppy/wiki/Downloads) in its default configuration. The only non-ADF file on the USB drive is an IMAGE_A.CFG which stores the last used image

Do you use Flashfloppy? I never had to mess with HxC config with FF and emulating Amiga images. I could check it again when I get back home. The DF0/1 swapping was necessary to boot from external Gotek drive though

Thanks for the update.. that's an interesting find. I'm still backlogged with other projects and things in life but since I don't want to give up on this printer I'll follow this thread closely. I hope I find some time this year to jump in on this topic again

No need to ask, the switches I've got are 3 pin so probably incompatible without additional modifications. They're just from the same series it appears

Is the coin cell still good? Not sure how they react to recharge. I assume the old one was NiCd, but th new ones are NiMH. I would have replaced it with one of those NiMh batteries, but if it works with the coin cell without causing CMOS errors, why not

Hmmm, I'm not convinced this is a 2.4V battery, because it looks like 3x 1.2V = 3.6V. See Varta 3/V15H S DA for example. Someone else could confirm or deny this... Additionally, did you solder in a diode, preventing the recharge current flowing back to the non-chargeable coin cell? The hard...

What type of battery was in there and what did you replace it with? You should not have the CMOS checksum bad message if you correctly replaced the battery (and cleaned/repaired eventual leakage and damage) If the IDE autodetect doesn't work you either have a bad HDD or have to select the HDD...

Are these those Honeywell SD series switches? I was about to ask if you're going to gut a keyboard I'd be interested in some spares (reason: the DIY solution I have isn't made for pounding on keys https://forum.vcfed.org/index.php?threads/alphatronic-p2-restoration.1244514/#post-1338755) , but...

My 8050's logic worked out of the box. I only reformed the big capacitors before turning it on. The drives are another cup of coffee, I had to completely degrease the worm gear, reapply it and also clean and lube the head carriage sled. Later on I had to replace the felt pad because the worn...

If you already get a pattern of lights and a steady green in the middle, you could be good to go. Try to hook up a PET and see if it repeats after turning it on, if it does it should be possible to issue commands to the drive. 7406 ICs can go bad for many reasons...