My display unit is already aging but the CPU is OK,so I decided to replace it with LED.The segments of this VFD are drived in DC -12V to +12V,I use some transistor to amplify current and convert Polarity for 4 byte Common cathode LED module,here are some pics.
Hey EagleBear, this thread is 9 years old, so I don't know if you'll get an alert about this reply, but I'm very interested in getting your help to make a few of these LED PCB replacements for the VFD bulbs. I have a Tascam 244 that uses the same VFD assembly as the 122mkII, and the VFD has shattered. I actively work on 4-track machines, so I'd like to get a replacement for this current machine and also have a few extras on hand for the future. Let me know if you're still out there!
-Jack