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Ask Rusty Your Own Question
Rusty, Music Professional
Category: Electronic Musical Instruments
Satisfied Customers: 5991
Experience:  Sound Engineer, Electrical Issues, Tone Consulting
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The sustain function is permanently on on my FP8 piano

Customer Question

The sustain function is permanently on on my FP8 piano
Submitted: 3 years ago.
Category: Electronic Musical Instruments
Expert:  Rusty replied 3 years ago.
Hello, my name is Rusty. Does the sustain remain when the pedal is unplugged?
Customer: replied 3 years ago.


Expert:  Rusty replied 3 years ago.
Ok, there is a short in that circuit. It's like the pedal is being pressed all the time. When you press the pedal, it shorts the circuit, and activates the sustain. This can be caused by two things when the pedal isn't the problem.

1. This works about 75% of the time. Unplug the piano, and hold any button for 30 seconds to drain the power. Dip the jack in rubbing alcohol. Run it in and out of the jack several times. Repeat this about 10 times. It will break up any tarnish in the jack. If it's a stuck jack, this will fix it.

2. If the above doesn't work, there is a short somewhere in the circuit. It will need to be serviced by qualified personnel. It is in your pitch bender circuit, so it's small and fairly easy to troubleshoot, by a trained electronics expert. If you want to pursue this repair yourself, and have a multimeter, and skills to use it, please let me know.
Customer: replied 3 years ago.

I do have a multimeter and am preoared to give it a go

it is not the jack socket as i have removed it.

Expert:  Rusty replied 3 years ago.
Ok, what you are doing is following the jack signal to the pitch bender. The pitch bender is small, and has a series of resistors. That feeds into your amplifier circuit, and is just after the tone generator.

You're going to have to ohm it out, and test for shorts. It is likely in the switch, just before it goes into the pitch bender. If that switch reads a closed circuit, that is the problem, and is what I expect. It should be open when there is no jack in the keyboard.
Customer: replied 3 years ago.

There is no pitch bender o an fp8

Expert:  Rusty replied 3 years ago.
Indeed there is. That is the circuit that produces the sustain. Although it's not connected to a jog wheel, there is still a pitch bender.
Customer: replied 3 years ago.

Ok - i understand. Have dinner at moment so look in to it ladter. Thsnkd

Expert:  Rusty replied 3 years ago.
Sounds good, let me know if you have any trouble.