I bought a nice Akai AX80 off ebay in 2016. It appeared to have no obvious issues and was in good condition.I overlooked these synths in the past, but they get some nice reviews and some of the pad sounds are excellent and very dark. Technically the AX-80 is a digital synth in that it uses a master clock at 6.55 Mhz. This is divided down and then into the D8253 counters. Analogue shapers then form the waveshapes.
Of course I set about it with a screwdriver
The VFD displays were a little dim and some striping across them. I replaced capacitors, cleaned the plastic cover and the VFD glass. This improved it somewhat.They may just be old. I'm not sure if they can be realistically refurbished.
The CEM3372 voice IC's
Here are some images of inside of another quite badly beaten up AX-80 I picked up. Spiders nest?
Classic interboard connector failure. An easy fix though.
Keyboard pads needed cleaned
In March 2017 I upgraded the firmware on the AX80 by using a willem EEPROM burner to add the super Tauntek firmware. This is the way the synth should have been all along. I used a SST27SF256 EEPROM.
The offset hex was 6000H for my K version of the AX80 firmware. One of the many benefits of this upgrade is that the filter cutoff now changes without having to trigger a key each time. Genius. It also adds SYSEX save and load! Plus the program number of the patch you may want to save is now displayed on the LED display! Check out tauntek for more details and for the new OS hex file. I have a spare chip programmed for the K version of the original AX-80 chip.
Below are some hi resolution images of the PCB's. Plus factory banks in wav format