Sylvia Else wrote:
The sustaining pedal on my Yamaha electronic piano is become rather
flaky. Sometimes it doesn't sustain when pressed.

So I disassembled the piano enough to get at the mechanism, (removed 12
screws, and 6 bolts), and was rather surprised to see that the business
end consists of a potentiometre.

I'm not really surprised that it's failing. In fact, the surprise is
that it's lasted so long. When a piano is played, the sustaining pedal
is in constant use. I can't help feeling potentiometres were never
designed with that kind of use in mind.

The design seems rather primitive.

Sylvia.

I just today received the new pot.

It's an odd device. Over most of its range the resistance doesn't vary.
All the change occurs within quite a small angle. This makes a kind of
sense, given that the pedal mechanism doesn't rotate it far. But it
seems to imply that the pots were specially made, which can't have
helped to keep the price down.

Sylvia.