Hi,
I own a Yamaha CLP 170, which has a GH3 keyboard. The problem is that this baby has been played for about 8 years now and now there is one major problem. Some keys tend to send a signal of full velocity even if they are only touched slightly. So when touching a key slightly and the failure occurs I get the loudest possible output for the key just touched. This does not occur everytime, but often enough to be very annoying. I also have not been able to reproduce the failure, it seems to occur randomly on about 5 keys of the Yamaha CLP. I called a Yamaha service station and it seems that fixing this problem is not a big deal. But the technician would have to come to my house, which would cost me 250$, because of the long way. Unfortunately there is no other repair service available that would be closer to my home. This is way too much for me considering the fact that the actual repair costs are less than this.
So here is my question: Do you think that fixing the failure described above can be done on your own without having much knowledge? If so, does anybody know where I can get Information on how to do the repair?

Thanks in advance

There really are no "hammer sensors". The sensors are simple contact switches that close as the key moves down and up. There are three switches that close at three different key depths. Velocity is determined by the time it takes to move between two key depths.

Likely all that is wrong is dirt in the switch. Dirt between the key and the switch might cause it to close early or open late

I shamelessly copied this photo from another thread in his forum. It shows the three sensors used in the GH3 keyboard. You can see them soldered tto the circuit board and how they get pressed by the key. My guess is that yor problem will be right there.

I believe this is a contact problem. If one of the contact is bad and the others do still work, then the keyboard can misinterpret a keystroke as infinite velocity or as zero velocity. depending from the fault location.

I dont believe in dirt, because the contacts should be hermetically sealed.

Possibly the contacts, that are made from siliconic rubber must be replaced.
Possibly the board with contacts must be replaced.
If you have measuring instruments and can exactly locate the problem, then you can possibly repair it with conductive color. I once did this for a GHE keyboard and that is A LOT of work, because all 88 keys must be treated the same way. Probably they all have some wear that will turn up in future.

Maybe you can buy a replacement keyboard. That is not difficult to install, but you will need the service manual.
Possibly you can replace it against an improved keyboard with Ivory Touch?

Peter

Here is what I found over at fixya:
fixya worn out clp 170
Seems to be the rubber. Thanks for pointing me in that direction and thanks for any answer given. I see if I can fix this one on my own.

Best regards.

The guy who wrote that "fix ya" artical suggested WD40. A very bad idea. WD40 is basically diesel fuel or very light oil. Not the best thing to put on plastic or rubber and it never completely evaporates. You can buy "contact cleaner" at almost any electronics store. This stuff works better, dos not attack plastic and rubber and completely evaporates, But before messing even with contact cleaner try compressed air. You cn buy cans of air in the same place as the cleaner if you don't have a compressor

The other good cleaning tool that works well in combination of the compressed air is an assortment of brushes, the kind used for watercolor painting.

One last resort... To avoid having to pay for some one to some to your home to fix the piano yo can easly remove four screws on the botom that hold the piano to the stand. Then the comsole piano becomes a slab piano and will fit even in a small car. The Yamaha P155, the YDP and CLP series are all the same mechanically and have four metal treaded insers on the bottom for the four screws. The user manual explains this and has pictures

Thanks Chris, I really appreciate your replies. I thought of transporting the clp by car, too. Problem is, I don't have a car and can't think of anybody who would drive me to the service station with that thing and back considering the rather long way to go. There will probably be a possibility for me to share the costs for the technician coming to my home, because I think it is likely that someone else living near me (considering that I am living in a town with 70000 inhabitants) want's his piano repaired, too. But that would still be 125$, so I am still looking into the alternatives. Thanks again.