Funny that you're just now continuing to work on your scope. Yesterday I livestreamed the aftermath of my repair and the calibration-process of my PM3323 on Twitch. The old boat-anchor is now working and performing well, despite me having no way to generate the low frequency Square-Wave and no way to verify the high frequency square-wave for its characteristics. Once I have the Signal-Generator running, that shouldn't be a problem anymore though
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
You're right, there are version-numbers on those chips. My D8303-Chip Label on the PM3323 shows D8720.2.
According to the Service-Manual, these Chips are 20R8, which are 20L8 (easier to google) with Tristate-Outputs. It might be possible to replace them with GALs from Atmel or Lattice if they support Tristate-Outputs. Unfortunately, I haven't been able to read the chips with my TL866 Programmer (I get a Read Error 31 and then a Warning about wrong Serial-Number with a link to the Website of the Manufacturer). The newer programmers also don't list the chip in their Supported Chips-List. Maybe it is possible to read the chip with an Arduino. But I haven't investigated that possibility beyond one google search.
I do have a defective P2CCD Board of a PM3323 here though. If you want to, I can ship it to you. It's the board that had a transistor release the magic smoke due to a dead P2CCD-Chip on Channel B. I have held onto it to salvage it for parts or sell separately.
Pretty interesting that they have put the chip that enables FFT onto the P2CCD-Board. Either the other chips were full, or they needed to record the Samples in a different way to be able to process them for an FFT later.
Btw. I have made another interesting discovery today: When I closed my PM3323, I transfered my modified A5 and A6-Boards from the PM3320A to the PM3323, which resulted in a crash.
I have identified the problem to be the CPU-Card A6, which seems to have some hidden configuration-jumpers that select whether it is a PM3323 or PM3320A (I didn't find the Jumpers in the Service Manual). I have then transferred the 68010 and the ROMs from the PM3320A to the PM3323 A6-Board and installed it and it works fine.
Installing the A6 Card in the PM3320A makes the Scope think it's an PM3323. I can also ship the A6-Board from the PM3323 I have disassembled. Maybe you can trick it into believing it's a PM3320A, or you can find the hidden configuration-switch for FFT if it isn't on the P2CCD-Board.