Disassembling FATAR keyboard to clean - Help!

Putting it all back together

Now that the weights are fixed its time to put it all back together again. Wait ! before doing that, take this opportunity to look around and do any other maintenance work that needs to be done. Its not often that the keybed is completely apart so check the felts, the key posts, the towers, aftertouch ribbons etc... You might also want to take the contacts PC board apart and clean those out also - go back to page 1 of this thread, Toddskins has it all laid out for you !

Putting back the rod that holds the keyweights in place can be a bit tricky, you need to work slowly and very carefully. Also, you may need to file or grind (to a slightly conical shape) the inserting end a bit; the rods I had were blunt and had a burr so it would have been very difficult to put them back in smoothly.

Position one weight at a time, rotate while pushing rod back in. When rod gets too short to grasp, lightly tap rod forward. Apply a very light coat of teflon lubricant on the rod to make it slide more easily. *** DO NOT *** apply excessive force - crunched felt, bent rod or broken tower posts could result ! Take your time.
 

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Conclusion: Final assembly and testing and... surprise!

The keybed is reassembled, the keys are all tested and everything looks fine for final assembly and testing.

Upon initial testing everything went well, almost. I originally had the highest B and C (B7, C8) that were intermittent. When I took the PC Board apart, everything looked fine and the board was a 2001 issue, it had already been replaced once because the other board is the original 1997 issue.

On testing, those two notes were still intermittent and had to be hit real hard to work. Since the side bell / panel was off, I started looking at the way the key was plunging on the rubber contact. Everything was fine ! It was then that I noticed that the front of the keybed wasn't laying completely flat ! So it seemed that it was bent or slightly twisted after all. Now how could that have happened ? The exterior enclosure is in pristine condition, not a single scratch or dent, anywhere ! Then I noticed something else: the power transformer brackets were very crooked on one side. So the only thing I can come up with is that this K2500 was shaken or hit very hard somewhere, at some point in its lifetime and thus, the keybed got twisted. And that my friends, was the most likely source of 80 % of the keyweights being too low and hitting the assembly and frame. That also solves an initial question I had in post # 93: "why is the weightline sloping toward the right ?" - because the frame is bent on the right side, that's why! The worn felt accounted for only a small porrtion of the problem.

To test that the frame was indeed causing a problem with the B7 C8 keys, I vise-gripped the keybed to the bottom of the enclosure and then tried out the keys. Eureka, they work ! The only way I could think of fixing this quickly was to drill a hole toward the front of the keybed frame and bolt the two parts together. It works ! There already is a screw that holds the keyframe to the enclosure but it seems it is just too far away from the edge & the end to straighten the keyframe properly. If you do notice a bent frame in your Kurz, whatever you do, don't try to straighten the frame by hand and don't just drive screws anywhere. It may look like a simple stamped metal beam but it is a precision part not to be fiddled with. Trying to unbend it will likely cause all sorts of other alignment problems afterwards.


So there you have it.

My K2500XS is reassembled and "like new" for a good while I hope. Now to get back to the real reason why I bought this thing: to enjoy practice and play music. Remember, I'm a techie but also a wannabe-musician ! Wish I would have gotten the urge sooner ... How sometimes life changes us :)

Jay
 

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Hey JaydeeMTL,

Doing a lot of study, too, on Fatar Keybeds, fixes, replacement parts, etc., and found a guy by the name Techeverlasting who wrote about the subject matter you just did. Read his comment at the bottom of the page. He says something about replacing the weight using a plier, but it is difficult, and something else about 2 metal poles. Do you know what he is talking about?

Read here: Fixing clacking Fatar keys - MusicPlayer Forums


FYI Good news - I read that the new PC3X keybeds are using a new design Fatar TP-40 which has one solid contstuction for the whole weighted piece, eliminating the lead weight inside the plastic container problems.
 
Hi Toddskins,

You're pulling my leg Toddskins! I'm sure that having worked on those keybeds before, you know what poles
he's talking about (Hint=post 101). When I was doing research on how to fix my keybed, the thread you
mentioned came up on the "Google is your friend" search result. His solution was intriguing and I might have
tried it if only *one* weight was broken; but I knew that because of age, it was best to really dismantle
everything and inspect for damage. Damage I did find, and lots of it, if you read my entire story starting
on post # 89.

I suppose that if you remove the red felt liner assembled to the keyweight, that it *may* then be possible,
with a pair of pliers or lots of human force, to squeeze the weight back onto the "pole". I predict
difficulty in putting the felt back in its proper position afterwards though, and it would then need to be
glued somewhere back onto the weight. It may also be next to impossible to put the rubber holder holding the
felt back onto the front of the weight. In any case, I wouldn't risk trying to stretch the keyweight nylon
seeing the part's age.


If I were a machinist, I wouldn't have fixed my keyweights, I would have done exactly what Fatar did on
their newer keybeds that you mention (I haven't dismantled one yet) - I would have machined new weights out
of an alloy and made it one piece, a much smarter way to do things and minimize breakdown and maintenance.
While I was at it, I would also have tried to make graded weights like they have on some Yamaha & other
manufacturer's keyboards. If that worked then I would have made a small business out of it... imagine all those
still good K2500's & K2600's collecting dust because the keyweights are almost unavailable now :)

My K2500XS has been in use for a little over 1 month now and the repairs seem to be holding up quite well.
For curiosity's sake I will open the keyboard again in 6 months and check out if the repairs were worth all
the time and trouble. Do you still have your K2500 ?

John
 
John,

I see now that you too, mentioned the rod, or pole, in the plural. But I only see one rod that the key weights get threaded by. Is there a 2nd? I thought there was a single rod threading all 88 key weights. Is it divided in half, thus there are two individual rods?

Also, I ordered that glue called "Plastic Surgery". I will be taking my K2500XS apart again, in a couple weeks and tackling this issue. I do not look forward to it at all, but when I am done, I'm going to do my best to make sure that the keybed is better and stronger than when it was first manufactured.

All in all, I got 10 solid years of playing mine without a key weight problem, but now I have 3 keys with that echo feeling in them (the weight having come loose/broken). If this Plastic Surgery glue owns up to all the positive claims I have read (not a single bad one!), then I will end up gluing every single key weight in all those critical places you identified in your photo (A, B, C).
 
Hi Toddskins,

There are two rods holding the keyweights. The split between the two rods is around middle C if I remember correctly so they are different lengths. From either left or right side, grab the rod with a pair pf pliers and gently twist / turn the rod onto itself back and forth while pulling it out of the tower posts. You'll find the split point when you hear oen of the keyweights gently "plop" down onto the chassis. Pull the rod out completely and note which end goes back in first for reassembly, it may need to be filed down a bit (read my previous posts starting around # 100). You can dismiss the use of the pliers once you can grab the rod comfortably with your bare hand, it is easier to continue pulling! Do read post # 101 on reassembly, it is a critical and delicate step.

I read that "Plastic Surgery" really is excellent for this kind of job. I couldn't find any around my area so I settled for what others also found to be good, the "J-B Weld" glue. The whole process of checking every weight with a magnifier and then fixing the broken or about-to-fail, weights is a tedious, time-consuming and boring task! Pay attention to hairline cracks - you can spot them because they form a sort of "fracture line" that is lighter in colour than the rest of the nylon around it. That kind of crack also sometimes doesn't yet reach any edge, but it is a sign of impending failure and its best to "bridge" the closest spot where you can put some glue. If a weight has fallen off completely, dab all the surfaces with glue and reassemble it, making sure you first roughen the nylon a bit where the pieces will meet. Don't be tempted to rush through it though; I mean, the whole keybed is apart and just doing that (and putting it back together again afterwards!) is pretty time consuming and beleive me, you don't want to have to take it all apart in 2-3 months because another weight is on its way out.

I hope all goes well with your repair. If you do this just for yourself, it is well worth it! I don't think such a large undertaking would be profitable for a prospective paying customer, its probably less expensive to buy a new keybed, provided one can be found of course - Doepfer may have some suitable replacements and maybe they are less expensive in the US, I dunno, but here in Canada the price is rather high.

Let me know how it goes!


John
 
Key bed weights

Ok, so I took it all apart again to fix 3 key weights that I knew for certain were giving me issue, and to do maintenance on all the weights, based on JaydeeMtl's (John) recommendations.

The good news was that I did not have any broken weights. Instead I had 3 of those plastic casings holding the weights, with broken tabs [see picture].

I found the tabs for 2 of the casings, but not for the 3rd. These missing tabs from the casing caused my notes to feel like there was an echo in the key when playing. I would strike the note (C4, G4, or D5) and there would be an after effect. Now I see that the weights sitting on the pole are able to pivot, and when notes are struck hard, the tab acts like both a shock absorber and a brake. Without it, the weight will bounce a little more. This is what I was feeling.

The glue called Plastic Surgery is pretty amazing. I spent a couple hours trying to think up a solution to glue a piece of plastic from around the house as a pseudo tab. What I found was an old belt clip for a device (not unlike a cell phone clip for you belt). The plastic is very hard and durable. I contemplated junk like plastic cassette tape holders, etc., but they are too weak, and shatter too easily. The piece of plastic I used came from a bend, thus providing me extra strength - essentially, a 90 degree, right angle turn, so that when I glued the one layer against the casing, it had a lot of support [see photos].

Turns out that the plastic I added, piggy-backed onto the casing, was too thick and caused a gap inside the key bed, so I had to file it down using a metal file, which did the trick.

I added glue all over the 88 key weights, as John had shown. Small fractures, and areas that looked like adding glue might add strength, and especially all around the Tabs. I play hard, and those tabs must take a lot of abuse. Adding more glue around them, should strengthen the joints, on all sides.

Regarding Plastic Surgery glue: I filed that added piece of plastic down after it had been glued down and it would not budge. I pushed the file against it as hard as I could, back and forth for 20 minutes, and it remained solid. Likewise, the 2 tabs that I had found, glued on tight against the casing, and are very strong.

You were right John, about filing down the ends of the poles into conical shapes. Threading the weights with the poles seems like the most difficult part of this whole thing, as the red felt inside the weights do get stuck and pushed. It's not until the end, when you seemed to have figured out the trick of it all to make it go easier, but by then you're already done.

One last point regarding Plastic Surgery Glue: There is very little glue in that container. I used 3 of them. Don't let the size of the glue container fool you, as there is only about a teaspoon of glue in the whole thing. But the glue is freaking amazing. It's kind of like liquid plastic, and it begins to harden in a few seconds, then a few minutes, and very hard after an hour. BE CAREFUL NOT TO GET THIS GLUE ON YOUR SKIN! It got on my fingers, and it's not fun at all trying to get it off.

I'll post once more tomorrow, after I put everything back together, and see how it plays. This is a 3-day process, and the more you look over the weights, you see more areas of possible fractures that should get more glue.
 

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Everything's back together, and plays perfectly. It wasn't that dirty, but I gave it a good overall cleaning. The touch feels better, like brand new. The 3 notes that were fixed, play perfect, and were relocated to the outer extreme ends of the keyboard, just as insurance.
 
Hey Toddskins,

So you did it! Congrats on passing the ordeal. Not an easy or fun task. That glue operation should last a good while. Anyways I hope so because I don't want to have to take my board apart again soon.

Yeah, threading the rods back into the towers and weights is quite tricky and requires careful and patient manipulation. You can't wiggle the rod to make it enter the felt loop and it seemed for me that only by turning the rod back and forth while pushing it in; all the while slightly propping the weight with my fingers so they would perfectly align with the rod, made it then possible to thread the rod through the weight. Slow going and still, a few did get crunched a bit. A jeweler's fine screwdriver helped to position the felt sometimes.

From the pics of your weights, they appear to be in better shape than mine were. Of course, I can't see the fine cracks and I hope there weren't too many.

So how long did it take you to do all that ? It was worth it though, wasn't it? Your K2500XS is now almost like new so you can now play away without worrying the keys will fall apart!


Was also wondering if you can check something out for me, a comparison test. On my K2500XS (+ KDFX + piano, contemporary & another ROM), I find that when I'm using any of the piano patches, say for example 771, all my notes after G6 sound "sustained" even when I release the key. They don't pile up on each other as if I was pressing the sustain pedal down but the sound is never dampened after the key is lifted, as it should, and as it does on every note below G5. I don't think it should sound that way so it may be a bug with the electronics. Then again, I don't have an acoustic piano to compare wether this phenomenon is normal on a piano past that note toward the top register (C7). Could you check this out on your K2500 and let me know if you experience the same behaviour, please ?


Happy playing !

John
 
Heya John,

Yeah, I do not like taking it apart and all. I get better at it each time, but it's still a feat.

Regarding Patch 771, what you describe is normal. Mine does it too. Starting at G6 those notes sound like they have more reverb on them (or more sustain).

Of course, you can change how that sounds if you want to. Every single everything is programmable on the K-series.

Have you got any other purchased Piano samples for yours? My favorite is still the original v.2 "Ultimate Grand" that Sweetwater programmed way back in 1997 give or take. I've purchased their v.3 Grand Pianos CD and other companies' Steinways and Yamahas, Bosendorfer, etc., and while I like them, I keep coming back to the evenness and clarity of the Ultimate Grand Piano sample. It's only 16MB and is thrown in with the v.3 CD-ROM from like 2002 (which has a 64 MB Steinway and a few others) if you get it. But the 16MB YoungChang v.2 is still my favorite and like I said, is included with the v.3.

Buy it here: http://www.sweetwater.com/store/detail/PianoCDv3/
 
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Hello everyone. My Korg sp100 restauration project also has the fatar keybed. Which is why this thread has critical information for me. Thanks for the detailed description.
But I have some questions left.
1. Does anyone know which felt I can use to replace the red felt on the hammer tips?
2. How can I replace one of these rods which hold the hammers in place? I bent one when I tried to pull it out (damn). The guys in the metal shop told me that it's a rare diameter: 3,6 mm (?!?) silver Steel (steel no. 1.2210; 115CrV3) and that they hadn't seen such a diameter before. So I cut out the bend, leaving me with 2 non-functioning keys and an area that's prone to fail soon from wearout (since I could not cut the whole bend perfectly)
 
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Sorry I don't know the answers to either of your questions, but the rod problem seems easiest to fix. Try hobbies and crafts stores. They're full of this kind of stuff. Take your cut out piece with you to compare diameters of metal rods. Even if you're unsuccessful at that, you could think about finding a piece of rod that might be larger in diameter for the 2 notes that are now not working, maybe 3 inches in length, and customize the rod into the holders for those two notes. I guess that would mean making the diameter of the holes that hold the rod slightly larger, using some type of drill-like bit. Make sure that the holes to rod relationship is proper and tight. You don't want holes that are loose, so that the rod is not snug. Last, you then need to make sure that the 2 key weights that sit on the larger diameter rod, rock smoothly with no gripping due to tightness. Here, you would want to consider thinning down the felt inside the key weight's hole, or possibly removing it altogether. Be sure to put a lubricant on the metal if you have to take this route.

Just brainstorming with you.

Regarding the felt on the tips, when I had mine out and was looking at those, I thought to myself "I'm glad these look okay cuz I wouldn't know where to begin in trying to fix that". On my Kurzweil, those red tips were sticky.

Again, look at your crafts stores, like Michaels, which is a huge chain store and has lots of stuff.

Get back with us when you have an idea and get our input. We'll be glad to offer our thoughts.
 
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Thanks for your reply and offer to brainstorm.
Some history (skip if boring :-D):
I got it for 55 Euros and I've been restoring it for the last week or so. When I got it, it was total junk. It was so dirty, I wouldn't even touch it. After disinfecting it with a lot of isopropyl alcohol and a total dismantle, I started cleaning every key, button and contact, some of the felts from the hammers and the two big felt strips under the keys. I found two places where liquids had corroded the left contact board and lots of junk under the rubber contacts. The panel that controls the buttons had to be cleaned as well and the potentiometer for volume control was corroded and stuck. I had to repair the right side panel, since the plywood had been soaked in liquid some time ago.
Since I had nothing to lose and wanted to broaden my knowledge on PCBs (and since it was a really cheap purchase :-D ), I went to work on the contact board.
I had to test every circuit on the right contact board (the left board was in good shape and completely usable) and had to bridge some circuits with wires and some with conductive pen; some of the contacts had to be renewed with conductive silver (luckily, I found some schematics of the contact board online).
I then made one mistake in bending this metal rod. I went to the local metal workshop and they told me there was nothing I could do to straighten it and that it was a diameter they wouldn't be able to get: 3,6 mm. They couldn't find a supplyer for this exotic format (I had a friend cut the bend out instead). Later, I found one online (but would prefer if I could use something from the local hardware store, since it's pricy). I found some cheap brass rods (50cm lenth max, 4Euros a piece) with a diameter of 3,5 mm at a hobby store but am not sure if that would be useable.

Still missing: one rod for replacement of the broken one; 3 pieces of felt for hammer tips (if everything fails, I may buy 3 new hammers at a local music store, though I'm reluctant in paying 8 Euros per new hammer if I only need 3 pieces of felt); black plastic foil or any other cheap alternative (maybe suggested by someone here?) for putting on the repaired side piece.

Now to your suggestion: I think it's great, but would prefer not to modify it more than I already did, since I have no idea if it would alter the action of the keys for the worse.
One big question are the hammers: They seem to be lubricated in some way and I wonder if I should use some silicon or teflon lubricant on the hinges of the hammers. I fear that without lubrication the felt in the hammer hinges will wear out soon. Did you notice any lubrication there?
Were the rubber contacts lubricated? Which parts of the keys need to be lubricated? (grease or spray?) I used silicon grease on the key springs and the wax like peaces where the keys rest on. I also applied some Teflon (PTFE) spray and the little movable plastic clips for the keys.
 
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If you have the opportunity, post a few pics of your keyboard taken apart, up close.

The rubber contacts definitely should NOT be lubricated. If you go back to Page 1 of this thread, you'll see my photos of rubber contacts and how to work with them.

I told you my red felts seemed sticky, so maybe that's some type of element Fatar added to the felts, though I have no idea. If you look at JaydeeMtl's photos (top of this page, post #102), you can see where the key rests/strikes the red felt tipped weight, and when the key is pushed down, it just causes the hammer to pivot on the metal rod. I'm not even sure that adding the sticky glue or chemical is important. I personally don't see how it adds anything to the mechanics. Maybe it just acts like an insulator, so that when the plastic spike coming down on the key strikes the key weight (on the red felt part) it's not noisy, although the red felt itself should accomplish that. I don't see any other purpose. Feeling, maybe? I don't know.

Or maybe that stickiness is excess glue used by Fatar when they glued the red felts to the plastic casing.
 
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Actually, I've just completed the reassembly and am just testing it right now. Some keys are sticky, meaning they move slower than others. Maybe I added too much silicon grease or too little. There's still unbalanced velocity over the whole board. I'll probably add conductive silver to all rubber contacts, not just to the worn out ones - but not today. For the moment I'd just like to enjoy my work. :-D
The next time I remove the keys I can shoot some photos, though it actually is the very same type of keybed as the one on the photos already in this thread. These were very popular amongst major brands: Roland, Kurzweil, Korg, Yamaha, Nord (I've been told they use differnt ones now).
Thanks for the tip with the lubircation of the felt. According to this I won't lubricate it. Probably it would have messed things up more than it would have helped.
You mentioned that it'd be bad if I used rod of a smaller diameter for the hammers. Would it really be a problem if I took a 3,5 mm (easier to obtain) instead of a 3,6 mm (really hard to get hold of)?
 
I think I said a larger diameter would be a problem, but only because it has to slide through those holes that are a certain size. The rod should fit snug and tight, I think.

If you use a smaller diameter, you have to think of a way to make it remain stationary, not moving as the hammers rock on it. I'm sure there are a lot of ways to do that.

Regarding the pics, I was thinking more along the lines of the other parts of your synth that you said you were working on and cleaning.
 
Hi Roloway,

ToddSkins has already answered most of your questions and I'm happy for you that your work has paid off in part.

There's not much sense in saying all this since the unit is back together again but concerning the rod that holds the keyweights, ideally you should try to find a same-diameter one. Failing that, maybe get one slightly larger and go to a machine shop and ask them to reduce the diameter using a CNC lathe or milling machine. If you now have more than 2 rods, I'm certain that the next time you take that part of the keybed apart, you'll have lots of problems because you can no longer grab hold of the rod(s) in between the 2 other ones . You may end up breaking things if you need to use a spare but long rod to push the smaller rod out.

Luckily, I did not have to replace the red felt tips either. And, like ToddSkins mentioned, there is some sticky stuff on one side of the felt to keep it in place on the weight. That stuff has a tendency to leak out a bit and bleed onto the other side of the felt sometimes but it does not cause any problems as long as it is not on the area rubbing onto the rod. The K2500's are well over 10 years old, mine is more like 14 years and there is no sign of wearing out of the felt at the area where it rubs on the rod - then again the friction is really minimal between the felt & rod. If the felts ever need replacement, maybe a piano shop would have the required material. I found this thread a while back concerning replacement and type of felt used, measurements, etc...

http://www.gearslutz.com/board/so-much-gear-so-little-time/514996-help-fix-fatar-keyboard-squeaks.html

You do not need to lubricate the area where the rod contacts the felt lining in the keyweight. The design is such that the thickness of the felt is just right for the diameter of the rod holding the weights in place. If the rod diameter is too small, it won't hold sufficiently onto the towers and the hammers will be somewhat loose and I suspect, noisier. If the rod diameter is too large, it may stress the nylon tower posts and also inhibit free movement of the weights.

I had a "squeaky keys" problem though after cleaning the felt area where the plastic key tab rubs and slides along the felt. I ended up having to dab a very very small amount of lubricant (simple petroleum jelly) on the felt tip to eliminate the problem. Don't put too much, it is not necessary and may even cause future problems.

John
 
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