Yamaha P200 Right Channel Cutting Out: Bad Component/Power Amp Board

[ZevonHead]

Hello all,

I posted a while back about the right channel of my P200 digital piano cutting in and out, and thought I had fixed the problem. Unfortunately I had not, and the problem persists. Basically, the right channel will be almost completely out or very scratchy, in every channel (speakers, headphones, stereo outs), and if I hit a big chord or tap the correct spot from underneath, it springs back to life for a while.

After many hours of eliminating different possibilities, I've finally more or less pinpointed where the problem is coming from. There's a section of the power amp circuit board with a relay that leads to a snap connection where the left/right signals leave the power amp (white wires/connection in the close-up pic below). If I take a chopstick and push down gently on the circuit board itself anywhere near that connection/relay, the right channel immediately comes back to life. I do not believe the problem is in any of the wires or the snap connection itself, as moving the wires around does not have the same effect. Does anyone have any ideas on what the problem could be? Is the circuit board shot with no hope? Could the relay be faulty and need replaced? I'm confident enough replacing components so if anyone has a solid guess based on the description, I would greatly appreciate it! Pictures below along with a link to the repair manual page with the circuit board in question. Thanks a ton!

https://www.manualslib.com/manual/1114969/Yamaha-P-200.html?page=20#manual

 

[delaware dave]

You might have a crack in the board, when jt heats up flexes and causes ghe faulty connection. If you have leaded solder you could try overlaying a heated solder iron on the traces and see if that helps. Can you wedge a chop stick in there to keep the compo ent propped up so that it flexes less?

 

[ZevonHead]

You might have a crack in the board, when jt heats up flexes and causes ghe faulty connection. If you have leaded solder you could try overlaying a heated solder iron on the traces and see if that helps. Can you wedge a chop stick in there to keep the compo ent propped up so that it flexes less?

I was worried about a crack.. I have repaired a crack before in the same way you described, so I potentially could do that. The only problem is I can't see an actual crack anywhere, so I'm not sure which trace to cross and where... I was thinking about wedging something in there like you said, but I'm worried that it might do more damage if it got jostled somehow (I want to take it to gigs occasionally). I actually realized a previous owner must have had the same problem, as I initially found a little rubber connector cap wedged between the connector and the relay to keep it tight. Obviously that wasn't a permanent fix though..

I just found replacement parts I could order including a new relay, a new connector base, and a new wire assembly for that white set of wires. Do you think replacing any of those parts, or even just de-soldering the connector post and re-seating it could do the trick, or is all that probably just a waste of time? Thanks for your advice!!

 

[delaware dave]

I was worried about a crack.. I have repaired a crack before in the same way you described, so I potentially could do that. The only problem is I can't see an actual crack anywhere, so I'm not sure which trace to cross and where... I was thinking about wedging something in there like you said, but I'm worried that it might do more damage if it got jostled somehow (I want to take it to gigs occasionally). I actually realized a previous owner must have had the same problem, as I initially found a little rubber connector cap wedged between the connector and the relay to keep it tight. Obviously that wasn't a permanent fix though..

I just found replacement parts I could order including a new relay, a new connector base, and a new wire assembly for that white set of wires. Do you think replacing any of those parts, or even just de-soldering the connector post and re-seating it could do the trick, or is all that probably just a waste of time? Thanks for your advice!!

I would carefully reheat the traces first and/or try the chop stick wedge first before sinking money into new parts. Just needs to be snug, not necessarily tight. Shouldnt hurt anything. I did the wedge with a power amp over 20 years ago, still in there and still keeps the bad channel working.

 

[ZevonHead]

I would carefully reheat the traces first and/or try the chop stick wedge first before sinking money into new parts. Just needs to be snug, not necessarily tight. Shouldnt hurt anything. I did the wedge with a power amp over 20 years ago, still in there and still keeps the bad channel working.

Thanks for the advice! I'll try it!

 

[Gourockian]

Another possibility is that you have a dry/dirty solder connection on the underside of the board. I would check out all the solder joints in that area, using the best magnifier you have available, giving particular attention to the pins of the relay and the connector. Make sure that they all have a nice smooth flow of solder around them. If you see one which looks different from the others, have it resoldered. Good luck.