AG7500 Philicorda keyboard restoration

Was restoring the oldest Philips Philicorda I own, which is AG7500/AG7600 all tube organ from 1965. During the years keyboard section has failed both electronically and mechanically. The design of the keyboard is not the best possible, so this is expected outcome for a 60 year old organ.

Conducting problems arise from the fact that contacts are wrapped to some sort of conducting rubber that has some sort of conductive coating on them. During the years they gather dust, which introduces noises and worsen the contact. Not sure what would be correct way to clean them, but any cleaning will wash out the coating and they don’t conduct at all. I ended up simply removing all rubber bits and just clean all the metal parts. Now it is just metal against metal as you would normally expect. That is not perfect either, but works.

The mechanical design major flaw are the plastic bits that have threaded holes in them. They are super narrow and as the plastic gets super fragile over the years, they will simply disintegrate. When that happens, keys don’t stay in their place anymore.

For black keys fix is easy as you can just replace the plastic stopper with a M4 nut and washer. I used locking nut. On the pic you also see all the rubber contacts removed from bus reeds.

For white keys this doesn’t work so I ended up making new stoppers from aluminium. I drilled the hole to a bit of aluminium, threaded it and cut and file it to mach the original stopper dimensions.

Rest of the mechanism is not that bad and after lots of scrubbing and washing and ultrasonic bath treatment I was able to rebuild the keyboard, which now works better than ever!