Roland FP2 electric piano

No R speaker nor R line out, L &R phones out seem ok, as does the speakers on/off sw. Amp hiss from the R speaker only, L is fine. I got inside this 7 octave thing without breaking any foil ribbons. The phones input socket switches seem ok, so does the line out sockets. But the Line-In Left/ Mono input has a bad bypass switch. Although it is in a position that would suggest a Ring contact it seems to be a tip contact switch, difficult to trace the local traces as vias etc. Anyone know if the problem there would cause the loss of one channel. As difficult to "bench test" this sort of item, any other areas to look at before some sort of reassembly?

Reply to
N_Cook
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The line outs, phones and power amp are all sourced from the same pair of signals, so if the phones work, the problem is from IC1 onwards to the IC3 power amplifier with regards the speakers, and there is a separate fault with the line out. Probably.

Incidentally, there are just two dual op-amps between line ins and line outs, plus a couple of mute transistors at the line out sockets, so this should be trivial to troubleshoot as it doesn't involve the rest of the keyboard at all.

I have the schematic on pdf I can email you, it is 6.4MB.

Cheers,

Gareth.

Reply to
Gareth Magennis

(Except the keyboard and Microphone signals are mixed with the line ins here, to appear together at the line outs)

Reply to
Gareth Magennis

speakers

I've only run it so far without the keyboard half connected, next time I come across one I will try external input feeds L & R before dismantling. These line in/outs seem to be simple mono so. with tip sw, no ring contacts for sensing of R-S connection of a mono jack. The "switching" logic seems to be if In-L/Mono tip is no longer grounded then feed that signal to both L & R amps ; if you feed a signal in the R as well and so its tip also is no longer grounded then defeat the signal from L-in going to the R ch , and allow the R signal to R amp. Or something like that, I still don't see why failed tip sw and no signal in there, would defeat the keyboard output to the R amp. The phones outputs were only operating as 2 mono outputs, now 2 stereo outputs from L&R ext inputs . Hopefully that tip sw failure was the cause . I suppose regular repairers of Roland and Yamaha pianos etc have long frames that can hold, open, both halves safely while powered up , plus ribbon extenders.

Reply to
N_Cook

If you need to play the piano whilst troubleshooting you can use an external MIDI keyboard and disconnect and discard the onboard one. I have in the past used extenders on large modular mixing desks, Lexicon

224's, and built my own extender loom for a Voyetra 8 synth module, but that's about it.

If there is no sound, you can check the operation or not of the onboard keyboard by putting an LED in the MIDI out socket and see if it lights when you press notes.

I don't know what you are saying about the switching jacks, they are wired very simply in the traditional manner. With nothing plugged into the right input jack, the left signal is passed to the right via the right switching contacts. With nothing plugged into the right output, the right signal is connected to the left output jack via the right switching contact. (there are mix resistors just before the jacks).

Gareth.

Reply to
Gareth Magennis

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No change, same loss of one speaker. I'll have to look out for some sort of basic midi keyboard for the next time, not one of my current bits of test kit. No convenient overlay marking of L-out/R-out on the main processor board or on the PA board. I don't suppose that info of which header/pins those signals should be on, is out there somewhere. I've found some long P-K bolts and with spacers should be able to fix the 2 body halves adjascent and 180 degrees apart , and work on powered up , to at least find where those audio signals lay. This keyboard has been dropped it would seem , stoving in part of the base chipboard , up against where the ribbons connect to the keyboard but as the keyboard works as such, then that local area was unaffected , I'm assuming. Then hopefully couple some test signals in there without the keyboard connected

Reply to
N_Cook

These might help

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Gareth.

Reply to
Gareth Magennis

I decided that lash-up too whisky. The digital seems quite well separated from the analogue on the PA board and 2 lines seem to come from off board to p2 and p6 of an M5218 dual op-amp SIP via electros from CN1 p6 and p8. Injecting 0.1V in those points carried through to both the speakers. That CN1 header traces back to the display board with vol and balance pots on it so a job for tomorrow

Reply to
N_Cook

I decided that lash-up too whisky. The digital seems quite well separated from the analogue on the PA board and 2 lines seem to come from off board to p2 and p6 of an M5218 dual op-amp SIP via electros from CN1 p6 and p8. Injecting 0.1V in those points carried through to both the speakers. That CN1 header traces back to the display board with vol and balance pots on it so a job for tomorrow

Whenever I get one side missing in something like this, my first port of call is usually the volume pot, as it is usually easy to access and scope, and/or short both wipers together.

Its a handy part of the circuitry to find out whether its the front end or power amp section.

Gareth.

Reply to
Gareth Magennis

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I'll know for next time. Low profile 7 pin ALPS 103B 502C pot, I could get tending to 0 fully CW and CCW pins 2,4,6 but not another triplet of pins. I did not realise these were bass compensation? centre tapped dual 10K pot tracks p2,4,6 one pot with 5K mid tap p1 p2,3,5 mid tap p7 and p2 common to both tracks presuambly compacted grease lifting the flimsy wiper, from getting inside. Hopefully that was the problem rather than me not realising these were non standard pots. Will try tracing the p6/p5 upstream signal side back to the main processor board or wherever for non-kbd testing purposes

Reply to
N_Cook

Back working again. Pin 6 and 7 of the vol pot is a good test point. They trace back via electros to p1&3 of CN1 jumpered via 0ohm Rs to CN4 p10&12 of the large ribbon and back to CN13 of the main processor board . Now to find something to cover over the hole in the chipboard and replace all the screws etc

Reply to
N_Cook

Should read pot Pin 5 and 6 for test points

At least Roland FP. are not as heavy and awkward to handle as Yamaha P..

Reply to
N_Cook

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