Yamaha P80 electric piano

I didn't expect the schematic to be out there, but it is. A simple control line between chassis socket and 1K to the main 168pin chip. So if no problem in that line then an unlikely and insurmountable firmware problem presumably

Loss of sustain, owner borrowed another pedal and a problem in the keyboard. Tomorrow I will clear the decks ,rig up strops and crane to open up. But if anyone has been there before and can point to what to look for and so minimum amount of time with the beast in bits then all to the good, to get all 7 octaves out of the way as soon as possible

People tread on the sustain pedal cable and beak or dry joint the jack socket.

It's highly unlikely to be anything other than that.

Gareth.

Loss of sustain, owner borrowed another pedal and a problem in the keyboard. Tomorrow I will clear the decks ,rig up strops and crane to open up. But if anyone has been there before and can point to what to look for and so minimum amount of time with the beast in bits then all to the good, to get all 7 octaves out of the way as soon as possible

People tread on the sustain pedal cable and beak or dry joint the jack socket.

It's highly unlikely to be anything other than that.

Except I had one of these keyboards in for repair about 6 months ago where the sustain didn't work, but that was because the whole PCB had been pushed into the keyboard. Someone must have given the sustain pedal jack plug a severe whack, or perhaps upended the keyboard onto the floor without first removing it.

Gareth.

I suppose one-man-bands who regularly repair P80/P100s and the like have a heavy duty frame for fixing the piano to, to safely take apart without damage to keyboard or human back. I've only dealt with P100 before and going by the P80 SM the process seems its possible to do single-handed without too much of a problem. I'll find out tomorrow.

Its usually broken PCB tracks under the sustain socket. I remove the socket, get rid of the broken PCB track ends, then refit the socket with a bed of hot melt glue, & finally repair the tracks with narrow de-soldering wick. Never had one back after this.

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Tetigisti acu (Titus Maccius Plautus 254 - 184 BC)

I suppose one-man-bands who regularly repair P80/P100s and the like have a heavy duty frame for fixing the piano to, to safely take apart without damage to keyboard or human back. I've only dealt with P100 before and going by the P80 SM the process seems its possible to do single-handed without too much of a problem. I'll find out tomorrow.

It is reasonably easy to prop such a heavy keyboard vertically against the bench, so all that is then necessary is to lift the end sitting on the floor up to the level of the bench, and site it upon it, with most of the weight pivoting on the bench.

You have then been able to lift said heavy keyboard onto the bench without actually having to lift its entire weight.

Goliath.

Relatively painless getting inside, no hoist needed. Ominously 2 bare steel paper clips loose inside. I wonder if stationery suppliers moved over to coated ones after representations from office equipment suppliers. Bad solder on sustain jack socket and also power switch solder going home, so redo all relevant solder points on those boards. No sticky keys so no reason to swap keys between octaves but anything else to check while inside?

Got the sustain to work with a simple switch externally but not with the supplied footpedal. Looks similar but no name and slightly different pedal shape. This one uses 2 conductive foam switch pads at top and bottom of stroke. So varying in a somewhat undefined way from about 30 ohm to about 160 ohm. 30 ohm as rest (internal sprung)state of one and

160 ohm as fully compressed (down), as set, on the other. Resistance changing between the 2 positions. It looks as though the P80 is on or off sustain not variable, correct?. Removed the "160" ohm membrane and it now works , going from 30 R to infinity, leaving the membrane stowed inside for anyone later to play with

The mechanicals of Y FC4 sustain pedal is in the P80 SM. Says switch assembly, not variable resistor, so I'll stay with the fudged no-name pedal and fit keyboard back in the casing

Another strange item to add to my jigs box. I've worked out how to reassemble single-handed and safely, support the weight of the keyboard while aligning and fixing (the awkward part) the casing around it. The screws for the rubber feet are longer than actually required. With keyboard propped against the wall, vertically, slacken the "top" 2 off and fix a wire coathanger around the 2 screws, tighten, deform the coathanger around the screws and reinforce the hook of the hanger with wire or tape, then hang that from a loop attached to a ceiling screw-eye or some other fixing point.

I ended up unwrapping the wire of the hook a bit and then cross-linking by wrapping around , to make a stronger hook. But it made it a doddle ,that over and under business at a relative angle while supporting the keyboard weight, minding not to break the wires , and then aligning for closure