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Kawai CA-97 disassembly / stuck key fix?
#2805972 01/24/19 12:14 PM
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Hi,

I have two stuck keys (E4, G4) on my CA-97. The keys are stuck, but the stuckiness can be temporarily broken, after which they just have higher resistance than normal. The effect lasts for a couple of seconds, then they're stuck again. It started out as them being slightly stuck and has progressed into them being unplayable over the course of some months (without use). I don't know if something was spilled, but I doubt it. I'm very meticulous about that and my children ought to be too (but you never know).

I've tried "breaking them in" by playing them lots and lots, but it doesn't fix anything.

So, firstly: Anyone got any idea what might be wrong?
Secondly: Anyone know how to disassemble it without breaking anything so as to have a look?

I've tried searching for repair manuals, but either Kawai keep them close to their chest or my google skills suck. Or both.

Thanks.

I haven't had time to play for... well, years, so I've just left it for a good while and the warranty is long gone, I think. Now one of my daughters are starting lessons, so it sort of has to work.

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Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2805977 01/24/19 12:19 PM
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Check this thread, it has a lot of information:

http://forum.pianoworld.com/ubbthreads.php/topics/2272103/Kawai_Grand_Feel_key_clinic.html

It's about the CA95 and the GF action, but most of it is applicable to the CA97 and GFII too.

The piano is relatively easy to open, via screws on the back. You have to disconnect a few speaker cables, but that too is not difficult.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2805984 01/24/19 12:25 PM
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That's an old thread, but it contains lots of good information.

If the piano is in warranty I'd seek warranty service.
If not I'd want to have the service manual before continuing.

Really really. Get one. It costs, but it's worth having.
I can't speak to the content of Kawai service manuals, but I'm betting they're similar to those from Yamaha.
Meaning ... very complete in all respects, including diagrams for disassembly.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2805985 01/24/19 12:25 PM
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Have you called Kawai to ask how much it would be for a tech to come inspect and fix the issue? It might be cheaper than you think (and for a CA-97, it would definitely be worth fixing, whatever the problem is).

And the action is pretty easy to understand, if you do care to open it up and look for yourself. The problem is there are parts (foam and felt pads, PTFE strips) that you may not have immediate access to in order to repair the issue.


Yamaha P-85, P-105, CP50, Kawai MP11 || Kawai NV-10
Re: Kawai CA-97 disassembly / stuck key fix?
MacMacMac #2805992 01/24/19 12:40 PM
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Originally Posted by MacMacMac
That's an old thread, but it contains lots of good information.

If the piano is in warranty I'd seek warranty service.
If not I'd want to have the service manual before continuing.

Really really. Get one. It costs, but it's worth having.
I can't speak to the content of Kawai service manuals, but I'm betting they're similar to those from Yamaha.
Meaning ... very complete in all respects, including diagrams for disassembly.

I've opened my CA97 (just out of curiosity, not because I had a problem) when I still had it without a service manual. It's really not complicated if you are a bit handy with a screwdriver. First you remove the panel on the back, then you see which wires go to the speakers in the top panel, so you unplug those. Then you can remove that panel, and so on. At some point you may have to cut or untwist some cable ties, but that's about the worst you need to do to remove enough panels to get access to the action. All quite doable as long as you proceed carefully and with forethought.

Of course once the action is accessible, then the question is, if it is possible for the layman to see or fix the problem. My guess is a problem with the Ptfe tab of the affected key.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2805998 01/24/19 12:48 PM
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I've disassembled the MP11 with and without the service manual. It's absolutely doable without, but the manual IS super handy as a resource. It warns you of possible "gotchas" too, such as sliding a piece of paper between two parts so they don't scratch as you move them past each other.

Not having the service manual wouldn't stop me from my own DIY, but it's worth giving Kawai a call and seeing what it would take to get one.


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Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2806004 01/24/19 12:53 PM
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Originally Posted by elendil
So, firstly: Anyone got any idea what might be wrong?
Secondly: Anyone know how to disassemble it without breaking anything so as to have a look?

This thread is about a different Kawai keyboard with a different keyboard action than in the CA97, but might be worth a peek.


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Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2806130 01/24/19 04:48 PM
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Wow, that’s a lot of quick, helpful replies! Thank you.

I’ll check out the threads linked to.

I reckon I would be able to pull it apart, but as one mentioned it’s just nice to know you’re doing it right and not accidentally breaking impossible-to-buy plastic thingies when you pry something apart the wrong way.

I should maybe have mentioned that I live in Denmark, so a service technician is out of the question, partly because Kawai isn’t a big brand here, but mostly because labour is crazy expensive.

I doubt it’s still under warranty, but I’ll give the (only) dealer a call. Who knows, maybe they’ll sell me a cheap service manual!

I’ll get back to you once i get it open and can’t understand what’s wrong with it.

Thanks again.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2806265 01/24/19 09:47 PM
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Hello elendil, welcome back to the forum.

Yes, I would strongly recommend giving your Kawai dealer a call, and possibly also Kawai's distributor for Sweden and Denmark, Juhl Sorensen. It's difficult to speculate what might have caused this issue, but perhaps the slip tape at the back of those two keys has come loose? If so, it should be a relatively straight-forward fix for a technician.

Best of luck!

Kind regards,
James
x


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Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2806616 01/25/19 01:55 PM
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Thank you, James. In my case they're the same and the customer support is good. I'll give them a call.

I think I'll try opening it up anyway to see if I can detect something immediately wrong. I'm scared of messing around with the keybed, but hopefully it's something simple as you mention. Since the behaviour of the keys are so distint, I'm guessing the problem should be apparant when you can actually see the action.

Unless it's under warranty a technician is probably my second choice due to cost and availability.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2806699 01/25/19 05:15 PM
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I'll be very interested to hear how you resolve this, I am having the same problem with my MP11, with almost all of my keys. No drinks have ever been allowed near it either.

Last edited by Oasismfg; 01/25/19 05:16 PM.
Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807314 01/27/19 09:26 AM
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I've come somewhat closer now. I took off the top case, which was straight-forward and with little risk of breaking anything, in the hope that I could then see and remedy the problem.

I can see it, but I'm not sure what the remedy is.

First: A working key:


Next: Sticky key:


Take a look at the pivot point of the hammer action. For the working key the movement is smooth. For the sticky key, the pivot point "jumps" out of shape.

Any guesses to the issue? I can't see how I'd be able to fix anything without removing the action, which is... scary.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807341 01/27/19 10:36 AM
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My guess:
You can see in your video the wooden part of the key at the bottom and the metal, screw-like part at the top (it's called a capstan). Between them you can see a thin black rubber cushion. What you cannot see is, that on top of that cushion, i.e. between the cushion and the metal capstan, there is a thin ptfe (teflon) film, to reduce the friction between the cushion and the capstan. The ptfe bit is like an adhesive film, like a bit of scotch tape (only ptfe). In other words, it is glued to the rubber cushion below with some adhesive.
My guess is, that this adhesive has failed in some way (maybe it got warm, or just old), and the pfte film has slipped, so the capstan is now no longer moving against the ptfe bit (with low friction), but is instead moving directly against the rubber cushion, at least partially, with high friction - or even worse, is even slightly sticking to the cushion, if there is a residue of the adhesive left.
If that is the case, then it can be fixed by putting a new ptfe bit into place on the cushion.
A technician can certainly do that. Or you can do it yourself, but then you need to source a replacement for the ptfe from somewhere. If you plan to do that, see the "GF clinic" thread I linked above. It also discusses this ptfe bit, iirc.
BTW, you don't need to take out the whole action to fix this. Each key can be removed separately. But you first have to remove the fallboard piece (the horizontal wood piece that bears the Kawai logo) - iirc, that requires to disconnect the cables of the tweeters (which is not too difficult) and another wooden strip beneath it that is screwed horizontally over all keys and prevents them from falling out.
All of this is doable (I know, because I did it with no ill effects), but should be done with care and forethought.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807349 01/27/19 10:52 AM
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I see what you mean with the hammer pivot coming downwards on the sticky key. Not something I ever noticed. It still could be a problem with the PTFE tab that either needs cleaning or replacing: if there's friction there, the capstan would not slide back so quickly so the falling hammer would not change angle, causing the pivot to drop (it's a kind of half-circle resting below an axel, rather than a fixed hinge).

You won't need to remove the entire action - if it's like the CA95, once you've removed the back panel, the top slides off and you just need to remove the key cover and tweeter bar to remove individual keys.


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Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807369 01/27/19 11:36 AM
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The pivot in the video is the white/cream colored plastic piece directly above the metal capstan. I don't think we can conclude from this that it is a PTFE pad issue, personally. But it really looks like a revolving joint is coming loose from its hinge.


Yamaha P-85, P-105, CP50, Kawai MP11 || Kawai NV-10
Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807410 01/27/19 01:35 PM
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Thank you for all of your points, gentlemen. I'll try giving the dealer a call and then removing the single key tomorrow if time permits and see if I can spot the issue. Glue or something similar coming undone could be a valid point, since we had a very long, very hot summer here, and I began noticing it in the fall.

You probably can't hear it in the video, but there's a really sticky sound like when your kid drops a lollypop on the floor and you discover it an hour later. In fact that's both the sound and the feeling.

I'll keep you posted.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807618 01/28/19 06:02 AM
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I called the dealer. They were very helpful, but: out of warranty as I suspected.

I took apart the key cover and the little bar on top of the keys for a better look. There is indeed friction between the capstan (thank you for the name) and the key for the offending key. In fact also for some other keys, but not as much.

I assume that there should be negligible friction between them, right? So that moving the capstan away from the key shouldn't result in any kind of stiction or "lollypop-off-of-carpet" sound. Is that correct?

Can I just pull out the offending key or are there considerations to take into account? In other words: If I remove the key, and maybe the rest of the action, can I put it back together again with little effort and especially little skill?

Now to source some teflon tape thingie.... hrm.

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807621 01/28/19 06:18 AM
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What action does Kawai recommend for such friction?
For my Clav the answer is ... apply lube to the capstan (and to some of the parts thereby driven).
Is that not the Kawai way?

Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807626 01/28/19 06:37 AM
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No lube on a grand feel action (grease is only used for the escapement tab). There should be a small foam pad with PTFE/Teflon tape on the key under the capstan (on an acoustic piano it would be a felt pad).

The PTFE tape has been reported to slide off in some cases (temp/humidity?) but can be replaced fairly easily (similar tape to what is on the bottom side of a computer mouse).


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Re: Kawai CA-97 disassembly / stuck key fix?
elendil #2807627 01/28/19 06:38 AM
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I don't know, but it's a good input, and it would surely make it much simpler to do this both now and as regular maintenance.

Through a very special form of telepathy, I've managed to have a glimpse at a Kawai service manual, but it expects a certain amount of knowledge of the reader, I think.
It mentions keyboard grease and has a few figures, but none of them refer to the WR action (even though it's from a CA-97 document) and for the WN action, they have red circles here and there. That's probably lubrication points, but then there are also black X's beside some of them, which could mean... don't lubricate?

Would you be able to chip in, James, regarding whether the capstan ends are to be lubricated? Your answer is yours alone and I won't and can't sue Kawai (or you, of course) if something goes wrong.

I know the obvious suggestion is to call the dealer and ask, and I'll probably end up doing that if I can't get the information here, but I doubt they'd readily know. They're dealers and acoustic technicians most of all (which is fine).

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