Electronic Repair

This is a Sequential Circuits Prophet T8 built around 1983, one of only 800 or so made. These have nice weighted keyboards with after-touch sensors under each key, and all the notes are triggered optically. It's the same keyboard as what's in the Synclavier. When this T8 arrived to my shop, it made no sounds at all, and when I fixed that part of it, I noticed all the presets were corrupt. The after-touch only worked on some keys, many of the keys had glued-on weights (pieces of lead, metal nuts, coins, etc) because of broken return springs. Many of the momentary switches didn't work, and there was a broken pot on the panel. After several months, I got it all working again, and replaced the after-touch sensors with a modern replacement made for the T8.

Here's all the work I did:

Resoldered output jacks to restore the audio, changed Lithium battery, replaced electrolytic capacitors in power supply, cleaned all panel connectors, cleaned all panel potentiometers and momentary switches, replaced broken Pressure Amount potentiometer, replaced all 20 tantalum capacitors with electrolytic in power supply and throughout instrument, replaced CEM3372 on Voice 1, installed new OS chips, vacuumed inside case and cleaned surface of control panel, removed key bed, and removed all keys, cleaned old cola spill from Pressure Board, removed 11 key hammers with broken return springs, replaced damper flanges, removed added weights from hammers put in place in leu of springs, replaced all key stop pads with new ones purchased from Wine Country, replaced both foam strips on keyboard,

installed Retroaktiv Synth's Pressure Board under key bed, and made a few adjustments on key actuators, adjusted optical fins and realigned opto sensors for key triggering. Reloaded factory sounds via tape interface.