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Damaged Keys? Help Please

Anything about hardware musical instruments.

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842 posts since 27 Sep, 2010

Postby synchronizer; Wed Jun 18, 2014 10:39 am Damaged Keys? Help Please

Hello. I am noticing that some of the keys on my less-than 7 months old digital piano are making unusually loud noises. I am not sure whether this is normal for a weighted keyboard. It is a Yamaha P-155.

Please take a peek at a rough video that I recorded:

http://www.youtube.com/watch?v=sMeld3U4 ... e=youtu.be

I don't think that the sounds are as consistent as they are supposed to be. The keyboard is not very old.

I hope that I have not damaged my keyboard...I admit that I had to place my laptop on top and I fear that it may have compressed the top after a longer period of time. (Silly I know) (I can slightly bend the top away from the keys, and the "thunking" noise seems to go away.) I do not have a long-term insurance policy.

What would you all suggest?
I am looking forward to responses. Thank you very much.
842 posts since 27 Sep, 2010

Postby synchronizer; Fri Jun 20, 2014 4:26 am Re: Damaged Keys? Help Please

~an honest bump
848 posts since 17 Apr, 2005

Postby JCJR; Fri Jun 20, 2014 9:45 am Re: Damaged Keys? Help Please

I'm not familiar with that particular unit, but construction of the keyboards is most likely still rather typical over time. Maybe today designed to be even easier to mass manufacture, though they got that down long ago.

From the days of the grand piano, thunks are often dealt with, using strips of felt and little bits of felt glued here and there. In modern times, you also see tiny pieces of synthetic rubber or soft plastic for that purpose.

I can't take responsibility for advising that you take it apart and inspect, especially if under warranty. But any keyboard problems I ever had, would just open it up and diagnose and fix the problem. They tend to not be crazy complicated mechanisms. You just have to be careful, look it over carefully at every stage of disassembly and reassembly.

Regarding some notes not playing the proper loudness-- Depends on the keyboard design. Some of the hammer action boards have little parts in there intended to feel like triggering the jack letoff mechanism in a grand piano. Some might have those "jack emulator" parts configured to trigger the key switches, rather than just being passive parts that impart a particular feel.

If the little jack emulator parts are in your keyboard, and they seem to actuate the keyswitches, would want to see if the weak keys appear to be hitting the keyswitches the same as the strong keys. Maybe something has got sprung on some keys.

Another common problem, especially in the case of high humidity, smoke or dust-- The keyboards generally work with a keyboard multiplexer scanning all the key switches very fast, and when it notices a key down or key up, it tells the little computer that sends midi and makes sounds. There are almost always at least two contacts per key, but very often both contacts are so close together it looks like one switch.

It most typically detects velocity because it is set up so that one contact closes sooner than the other. The key scanner measures the tiny time delay between switch closures to measure the key velocity.

Often this entire "smart" system looks to the eye like a little rubber nipple or half tube, sitting on a circuit board. The little rubber caps have under them tiny bits of conductive plastic that close switch contacts on the circuit board.

If a rubber piece gets damaged or loses its spring, then velocity sensing can't work correctly.

Even if the pieces are not damaged or worn, the contacts can get dirty, especially in dirty or humid environments. That can affect velocity or even make a dead or intermittent key.

One can in that case remove the circuit board, carefully pop off all the rubber off the board, carefully use q tips and 91 percent isopropyl alcohol to clean off all the circuit board contacts and conductive plastic bits under the rubber nipples.

Maybe some plastics would not like the alcohol. Test a bit to make sure it doesn't melt. Otherwise, have to look for advice on a gentler cleaner solvent. Don't use lubricating contact cleaner or any kind of oil on the plastic switches. In my experience a lube will kill conductive plastic switches deader than a doorknob. So dead that they don't even work after careful de-greasing.
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70 posts since 7 May, 2014

Postby PsYcHo SaMuRai; Fri Jun 20, 2014 9:56 am Re: Damaged Keys? Help Please

Do you mean the clunking noise isn't consistent or inconsistent audio? If it's just the keys then it sounds like your key weights are clunking. Some keyboards just have loud weights. If you can, compare it with the same model. In shipping, it may have been jostled a little bit where the rod that holds the weights has shifted slightly. Hopefully, it's not cracked key weights but I don't think so.
The clunk won't be consistent because Yamaha uses slightly different amounts of weights on their keys to give it a more realistic, acoustic grand piano feel. Weights get heavier from high to low with some slight variation throughout.
842 posts since 27 Sep, 2010

Postby synchronizer; Fri Jun 20, 2014 12:12 pm Re: Damaged Keys? Help Please

Thanks for both of your responses.

I am referring to the loudness of the "clunk". I admit that I made a mistake when I decided to place my (somewhat heavy) laptop on the back of the keyboard. I do not have a proper drawer or desk to place the keyboard in front of my computer, and I have to work closer to the screen.

As a result, I think the wood got a little weaker (I press it and at times it makes a slight cracking noise as if it's bucking under pressure.) The good news is that the velocity response that I get from the keys doesn't seem to have been affected. I cannot really hear the difference when playing either, and part of the issue may have to do with an oversensitivity to sound on my part.

Anyway, I will not be deconstructing the keyboard, but I want to prevent problems in a future.
I live in an area where the summer becomes hot and humid. In addition, I have not had the time (until now) to maintain the keyboard as well as I should have. There is plenty of dust under the protective cover now.
What is the safest and easiest way to tackle the dust problem? I would think to use a cloth that is particularly good at attracting dust and simply wipe the keyboard and whatever openings/gaps possible.

I hope that I made the situation clearer. Thanks again for the responses.
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70 posts since 7 May, 2014

Postby PsYcHo SaMuRai; Sat Jun 21, 2014 12:55 am Re: Damaged Keys? Help Please

I'd just dust it and wipe it down every so often. Then, get a dust cover or bath towel to cover it up when not in use.

If you have cats, KEEP THEM OFF OF IT. I hate repairing a keyboard to find stinky, dried up, caustic cat urine has eaten through the key contact board or worse. Something about their owners smell on the keys or something but I've come across it too many times. yuck!
842 posts since 27 Sep, 2010

Postby synchronizer; Sat Jun 21, 2014 6:40 am Re: Damaged Keys? Help Please

Thanks, and the second concern won't be a problem.
848 posts since 17 Apr, 2005

Postby JCJR; Sat Jun 21, 2014 8:00 am Re: Damaged Keys? Help Please

Re the wood on top of the piano-- Is the piano on a piano stand, desk, table, what?

If there is a stiffness problem then possibly laying a piece of half inch plywood over the piano top would stiffen it up for your laptop and such. Maybe 3/4 plywood but that is probably overkill.

If in a desk or table, maybe a little inverted-u-shaped shelf with little legs extending down to the desk surface on each side of the keyboard. Sitting up barely higher than the piano. It could be deeper than the piano to hold equipment better, and keep weight off the top of the piano entirely.

Something that can be good material for such accessories-- white melamine mdf shelving. It looks good enough. You don't have to paint it. Easy to clean. Reasonable cost. Fairly tough surface. Tends to be straighter and flatter than plywood. Not for outdoor use or frequent travel, however.

I'd trust the 3/4 or thicker better for this application. Half inch might bend or sag over time. OTOH that could be solved with a wood runner under the bottom rear of the shelf, to act as stiffener.
842 posts since 27 Sep, 2010

Postby synchronizer; Sat Jun 21, 2014 8:07 am Re: Damaged Keys? Help Please

My laptop was a bit too heavy for the keyboard I think. It is definitely not light. I would have to have something hang over the keyboard if I wanted to place my laptop above it.

I noticed that the part of the case that has the red stripe found on most keyboards is SLIGHTLY flexible. (I can nudge it/bend it up and down.) The buttons on the top do not make a consistent sound either.

It seems that the top was pressed down a little bit, but I haven't put my laptop above for a few days. Maybe if I am lucky, everything will readjust. I am not sure.
I could post more short videos if doing so would be helpful.
848 posts since 17 Apr, 2005

Postby JCJR; Sat Jun 21, 2014 8:14 am Re: Damaged Keys? Help Please

If you mean the red stripe visible in your video, that is a strip of felt. Felt is a rather amazing material to be so mundane. Grand piano action is amazingly precise and durable, made mostly of wood and felt, with a few tiny bits of steel and leather or fabric to hold it all together.
842 posts since 27 Sep, 2010

Postby synchronizer; Sat Jun 21, 2014 8:16 am Re: Damaged Keys? Help Please

Sorry, I mean the piece of the case that is attached to the felt, not the felt itself. I can lift it a little bit and the keys don't make as loud a banging noise in some spots. Maybe it got "crushed" down by the laptop? I hope not. Truly I would like to think that my equipment is fine.
848 posts since 17 Apr, 2005

Postby JCJR; Sat Jun 21, 2014 8:39 am Re: Damaged Keys? Help Please

If the keys feel ok when you are playing them, they all have about the same resistance, and they all seem to have proper velocity response, then there is most likely nothing wrong with it.

If the top has sagged a bit and is causing a clunking sound in the case, then most likely all that could be adjusted out. Open it up and shim the top a bit or whatever is necessary.

Dunno the exact details of your key mechanism. The only "hazard" might be if your keyboard has little moving parts to emulate a piano jack letoff, which are clunking against the top. If that were the situation then maybe the little pieces wouldn't appreciate repeatedly hitting the top of the case and eventually break.

I don't have any clue, the odds of that, except calling and asking a yamaha service tech or opening it up and looking inside.

If you are uncomfortable opening it up, I'm guessing there isn't much wrong with it, and a local keyboard tech might not charge you too much to look inside and adjust it if he finds anything wrong. If he finds little wrong, then maybe it would be worth the money so you have one less thing to worry about. :)
842 posts since 27 Sep, 2010

Postby synchronizer; Sat Jun 21, 2014 8:41 am Re: Damaged Keys? Help Please

Yes, and I don't live anywhere near a Yamaha service shop. There is ONE black key that feels a little odd...but there are multiple sections of keys that have varying hammer responses to emulate a real piano on some level.

I probably should let it be for the moment.

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