Yamaha KX88 key installation, aftertouch strip, lube

I just brought a Yamaha KX88 with no MIDI output back to life by replacing IC16, the hex inverter that is a 220-ohm resistor away from the MIDI OUT jack. I have some other issues that I want to ask about:

  1. The leftmost black key was sticking up oddly. The service manual was sufficient to show me how to remove keys and I took off the white A key to the left of the sticking-up key and the affected key, part of which was broken off and needs replacement. I like to look ahead as I work on these things and what the service manual had nothing to say on is how does the return spring fit inside the key? I could tell that the “male” end (the end with the protuberance in the center) of the spring fits into a kind of socket in the frame by looking at the adjacent B key but looking up inside the removed keys it’s not clear to me where the “female” end goes.

  2. I have not had occasion yet to test the aftertouch. I know we can expect for the necessary force to get a certain AT value gets higher with age and I have a KX76 that exhibits that behavior. I also know that there are zero and gain adjustments for the AT but before I even get there - again, I’m trying to think ahead - if I remove all the keys for cleaning and possibly re-lubing the pivots etc. (pursuant to my being able to get them reinstalled per 1. above) the AT strip is going to be right there and keys-off would be the perfect time to replace it (assuming Syntaur has them in stock). Mostly I want to first see if it’s absolutely dead so does anyone know what the nominal resistance range of that strip is? For what it’s worth, cycling back and forth between no keys depressed and leaning pretty hard on a triad (not trying to max it out, just as much pressure as I’d feel like applying in actual performance) runs the strip resistance between about 7k and 400 ohms, which seems like a pretty healthy excursion, not knowing any better.

  3. I note that the pivots at the back of the keys are lubricated with some kind of grease and it looks like there are other contact points around the front of the key that has the grease also. I don’t want to try to “hot-rod” this controller but I would like to have it working to spec feel-wise, so what kind of grease should be used on these keys?


Im following this, Im not having the number of repairs and maintenance as you have, but I do have an issue with removing the keys procedure. Trying not to break anything. Any literature besides the service manual on how to remove keys ?

Along the back of the keyboard assembly there is a plastic strip, about 5/8" wide, that is held on by a handful of screws; the very back end of the key hooks over the top edge of it so it’s kind of like a retainer for all of the keys. Remove that first. Then the key and its pivot can then be slid forward roughly 1/8" until it stops. Then the key can lift straight up. Now, note that I haven’t figured out how the return spring is supposed to be reinserted; when the key is lifted up the spring will just fall out. The pivot and the key will come out together but they aren’t attached to each other at all; if they’re stuck together it’s just because of the grease. It kind of works like an elbow joint. I’m really excited to be on my way to getting this controller back into service; it was considered top-of-the-line back in the day and there are folks even now who swear by them. Keith Emerson used one in the ELPowell days and of everything available on the market, the KX88 was what Ray Charles chose to tour with.

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I just removed all the white keys so let me add something. Once the retainer strip is removed there is nothing keeping the keys from sliding forward but you may have to give it a strong push. Remember that what’s on the very back end of the key is the pivot so if you push forward on the back end of the pivot, it and the key will move together. Nothing is connecting the pivot to the key but the suction of the grease. Incidentally, I took off the next lowest key more carefully and got an answer to my question about where the return spring goes. The key is more or less a channel that’s open on the underside and up under there toward the pivot end of the key there is a rib that runs down the center horizontally and makes a right-angle turn downward. The notched end of the leaf spring just crudely rests on the right-angle turn of that inner center rib; that’s all there is to it. The leaf spring sticks through a hole in a vertical component of the key structure and the lower end of the spring - the end that has the little tab sticking out in the center - fits into a socket built into the metal frame. Hope this helps you and those who come after us.

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Thanks for the help on this, I have a few black keys in the middle of the board that are sticking. Really is a pain. I wish I could see where the spill from the last owner, but he said he tried to clean it as best he could. Now like 15yrs later, it starts sticking again.

Oh yea, did you ever find out what Grease is used on the pivot points ? I have all my keys removed and cleaned the spilled coffee, (I found out to be ) from the last owner. Makes me wonder that if I do not place any grease, what would happen. I didnt clean that elbo to good because im not sure whats coffee and whats grease in the small slot. lol

Actually I may have found the grease type. Looking on the net, Someone asked about yamaha keys and the grease used on Motifs. They said :

(From personal notes, the info I have is that Yamaha uses the following lubes…
VD456002 “Key Grease” 50 Grams - $61.32
(used on the hammer and pivot point of the key)

TX920270 - “Silicon Grease” 100 grams - $81.32
(used on the rubber key guide in the front of the key)

this guy Said…
I’m not sure they apply, and as you can see, they are ridiculously expensive. If there is some “spill over” of the gooey lubricant on the other keys, you just might be able to accumulate a sufficient amount by scraping it off and applying it to the ailing key. Wish I could be more helpful.

Interesting: found this on Ebay…

Yamaha white key grease:
White Yamaha Grease for key guide and other points CLP CVP, P, Motif V627430Y | eBay

Blue yamaha key grease:

Blue Yamaha Grease for key guide and other points CLP CVP, P, Motif AAX9071Y | eBay

White Yamaha key grease for guide and clip:

couldnt post 3 links, but another one said Yamaha key grease for guides. also on ebay, in a clear tube like.

Without knowing anything about the design of those other keyboards, I’m reluctant to just pay that kind of money. Here’s what I know, though: it can’t be any kind of petroleum-based grease. That leaves silicones and PTFEs (Teflons). The viscosity of the grease - specifically, how a thin layer of it responds to shear - is going to have a significant effect on how the keyboard feels. Resistance to motion in shear is a second-order response, by which I mean if the spring produces a force that depends on the position of the key, the pivot grease produces a force that depends on the motion (specifically, the angular velocity) of the key. If the key pivot were just a small axle that was, say, 2-3mm across, it wouldn’t be a big deal but on the KX88, the pivot radius is more like 15mm and is about 10mm wide. With the grease between the mating surfaces, the pivot acts as a governor; like I said, it resists motion distinct from and in addition to what the return spring does. It has everything to do with how quickly the key returns to its position. So if that grease is too thick, everything will feel “gummy” and “tough.” If it’s too thin - like if you used vegetable oil (don’t do that!) - it’ll feel more like the KX76. Another thing to look out for is the grease’s temperature sensitivity - You don’t want the keys to take a half second to rise up if the keyboard is 50F and you don’t want it to run out of the pivots if the KX88 is sitting out in the sun.

Update: There’s a technology store in my town that sells Caig products and I saw they had DeoxIT L260DNp, “Precision Lithium Grease” with no particles (very important - you can get L250D with copper, aluminum, graphite, quartz, or graphite and quartz particles). I checked Caig’s web site from my phone as I stood there and they had a “feature matrix” for their greases which indicated that L260DNp is safe on sensitive plastics. It was one ounce for $11.

I’m going to clean up one key and one pivot, put the DeoxIt grease on, reassemble, and see how that feels just moving the pivot with my fingers compared to an OEM-greased key/pivot combination to get an idea what the shear resistance is. If they seem comparable, once I’ve cleaned up all the keys and pivots, I’ll try putting on an octave of keys back onto the frame and see how they feel,

Just to follow up, I’ve finished overhauling and reassembling the entire keyboard using the aforementioned DeoxIT L260DNp grease and it feels tremendous. Very consistent all up and down the keyboard. And let me tell you - there is a trick to reinstalling these keys and I’ll try to describe it best I can. the upper-rear end of the leaf spring has a little cutout in the middle and the idea is to set that cutout right in the corner of a ridge that’s molded underneath the key. But if you stick the spring through the opening in the “arch” that’s molded mid-key and push the end of the spring toward that corner, it’s liable to get stuck before fully seating. In the top of the key there is a rectangular hole and that hole is just the right size for the screwdriver/file blade of the smallest Swiss Army knife. You can stick that blade through the hole and push on the spring to unstick it and let it settle fully into that corner.

There are black plastic guide blocks that are part of the frame and fit up underneath the keys. Old grease was left behind on those keys, so once all that is cleaned off I put a small blob of grease on either side and right on top of those blocks. The blocks limit the key travel from side to side so if you’re getting your Ray Charles or Jerry Lee Lewis on, the keys are going to come into contact with those guide blocks while moving up and down.

Now here’s the harder part: Once you’ve greased and fitted the pivot and gotten the spring nestled into the corner up inside the key, you’ve got to install the key. There are plates screwed to the frame that help form a square-ish socket for the forward/bottom end of the spring, and you’ve got to get the end of the spring in that socket - and you may have to do that blind, like if you’re putting in a D key between C# and Eb. The way you do that is to poke that same Swiss Army knife blade through the hole in the top of the key but this time aimed forward and down so that you can use the handle end of the knife as a lever to bend the end of the spring downward, far enough that you can aim the end of the spring to the socket and, as you work the key into position, you can aim the end of the spring at the socket as you lower it. There’s a rectangular…platform?..on the bottom rear of the key that fits through a rectangular hole in the frame and you have to apply force against the spring to get that platform into the hole but once it’s through, the entire key is ready to practically slide itself rearward a fraction of an inch as it’s held down and then the key will be installed.

Thank you.

I had to replace the bushings in my PAiA Proteus, and the recommendation was to use white lithium grease. Well, that can’t be right… The grease I used became somewhat sticky and the keys would stick.

I found a tube of the L260DNp on Amazon. There was also a tube of L260NP that could have worked - the same grease, but without the deoxide - but the difference in cost was minor. The deoxide may be useful down the road.