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 Forum index » DIY Hardware and Software
How do I disassemble Matrix 6 keyboard? (solved)
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peterm



Joined: Aug 25, 2009
Posts: 11
Location: Malmö, Sweden

PostPosted: Wed Nov 25, 2009 4:51 pm    Post subject: How do I disassemble Matrix 6 keyboard? (solved) Reply with quote  Mark this post and the followings unread

Hi all.
I'm not sure this is the best place to ask but since I didn't have any luck in finding a more suitable place, well, I ask here Smile

As my first attempt at reviving a synthesizer I bought a dead Matrix 6 that I managed to convert from 120V to 230V by altering the fuse board.
After replacing the volume slider with a rotary pot I got the synthesizer to power up properly and after calibration I now have all 6 voices working fine as well. Some keys here and there don't respond at all though so I want to remove them and see if I can fix the contacts.

I have opened the front panel and flipped it back, exposing the PCBs and the rear of the keys.
It looks like I'm supposed to be able to "pull" a key forward and lift it up in the back to unhinge it but it doesn't seem to quite manage to let go.

I don't want to use too much force so I'd rather ask before I do something really stupid. (2 keys were broken when I bought it but I don't want to break any more).
Is there something else I need to do to be able to remove the keys? I mean it looks really simple but they just won't come off. Can someone please tell me what the trick is please? Confused
Or please direct me to a more suitable forum?

thanks,
Peter

Last edited by peterm on Thu Nov 26, 2009 12:12 pm; edited 1 time in total
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Dan Lavin



Joined: Nov 09, 2006
Posts: 628
Location: Spring Lake, Mi, USA
Audio files: 21

PostPosted: Thu Nov 26, 2009 7:06 am    Post subject: Reply with quote  Mark this post and the followings unread

Peterm,

Welcome to the E-M Forum!

I'm not familiar with that exact keyboard, but I've taken plenty apart over the years. Generally, there is a spring at the back of the key attaching it to the frame. That has to be removed first. After that the key should be able to be pulled out. Yes there are many tricky ways to attach keys and I'd be lying if I did break some in the learning process. If you're still having problems, I'd suggest taking photos and posting them. Me, or someone else may recognize the exact keybed and can offer better suggestions.

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peterm



Joined: Aug 25, 2009
Posts: 11
Location: Malmö, Sweden

PostPosted: Thu Nov 26, 2009 7:43 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi and thanks for your reply.
There is no "coil"-like spring in the rear of the key if that's what you mean. There's a bent metal piece as a spring instead a bit further to the front underneath the key, if that makes the type more easy to identify? Smile
I'm at work atm so I can't provide a photo just now. I'll try to remove some key again when I get back home or post a photo of the mechanism if I fail again Smile

Also, do you have any suggestion for glue types if I want to repair a broken key that still is in "one piece" (i.e. both halves are still attached somehow but it'll fall apart any day if I touch it) but it's just because something is holding the pieces together in the bottom I think.
I posted a photo of that on my newly created "synth blog" for my projects.
http://synthpeter.blogspot.com/2009/11/oberheim-matrix-6.html
Or just look at the pic below:
Posted Image, might have been reduced in size. Click Image to view fullscreen.

Someone suggested superglue (CA-glue) but I'm afraid it might be too brittle to handle the bending force of keys being played. I was thinking perhaps 2-component epoxy might work but I really have no idea.
The break is not clean of course so any glue requiring a smooth surface might not work. What type of plastic are the keys made of? I guess that also decides which type of glue to use.

Thanks for helping.

Cheers,
Peter
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Dan Lavin



Joined: Nov 09, 2006
Posts: 628
Location: Spring Lake, Mi, USA
Audio files: 21

PostPosted: Thu Nov 26, 2009 7:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Peter,
Is the metal spring vertical (parallel to the back of the key? If so, you need to lift the key up over the metal piece. There is probably a plastic tab on the back of the key and a square hole in the metal, so you'll need to get the tab past that point, then it should slide off.

Gluing plastic keys has always been a challenge. I agree superglue probably won't work. I'd go with a 2-part epoxy as you suggest. It's been a while since I glued keys, so I don't remember which 2-part epoxy I used last. Not all of them are good. You may have to glue more than once.

It definitely sounds like a non-Fatar keyboard which means replacement keys will be hard to find and gluing is probably your best option.

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peterm



Joined: Aug 25, 2009
Posts: 11
Location: Malmö, Sweden

PostPosted: Thu Nov 26, 2009 8:33 am    Post subject: Reply with quote  Mark this post and the followings unread

From what I can tell the spring looks like a hard-edged C resting on the bottom of the keyboard and pushing the key upwards.
I remember that there IS a plastic tab at the rear of the key that seems to aaaalmost fit a slit in the metal so I think I should be able to lift it up in the back there. The problem is I can't quite get the plastic tab through (seems like 1mm too long or so) and I am wondering if something else is keeping the key down (except the stop at the front but that shouldn't keep me frmo lifting the rear) or if I just have to use violence...

According to this site:
http://sounddoctorin.com/synthtec/parts/key.htm
...the Matrix 6 keys should be replaceable by AX-80 or Kawai K3 keys (although they are weighted but the weight can possibly be removed if you're lucky).
You can see a photo of the Matrix 6 key here. The tab I'm talking about is at the bottom left of the picture.
http://sounddoctorin.com/synthtec/parts/matrix6.JPG

Thanks again for your help!

Cheers,
Peter
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peterm



Joined: Aug 25, 2009
Posts: 11
Location: Malmö, Sweden

PostPosted: Thu Nov 26, 2009 12:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey I managed!
If you look at the photo above the plastic tab down to the left has one on eash side of the key (rear right and rear left).
Each of those tabs have a small "lip" protruding inwards so it kind of latches on to the metal.
I tried spreading those tabs apart a bit and then the key popped out, along with the spring of course but I found it Smile

Thanks for your help!

/Peter

Last edited by peterm on Thu Nov 26, 2009 5:42 pm; edited 1 time in total
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Dan Lavin



Joined: Nov 09, 2006
Posts: 628
Location: Spring Lake, Mi, USA
Audio files: 21

PostPosted: Thu Nov 26, 2009 5:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

Peter,

Glad it worked out. Yeah, those are funky keys! At least nowadays most follow the Fatar standard, so it's easier to figure out and get replacements.

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magman



Joined: Feb 04, 2009
Posts: 362
Location: Liverpool, UK

PostPosted: Sun Nov 29, 2009 5:45 am    Post subject: Reply with quote  Mark this post and the followings unread

If you struggle to get the keys repaired, you might be lucky and find some replacement keys here:

http://www.vintageplanet.nl/content.html#parts (search for Oberheim)

They appear to have some keys in stock, but they aren't particularly cheap at Euros 10.50 each.

I've got a similar problem with a key I broke on a keyboard I'm very unlikely to get spares for (A Clef CMS, of which I think less than 100 were made). I'm going to try to fit thin strips of aluminium under the repair with epoxy, so that its not just the glue that is giving mechanical support at the joint. Might be worth a try with your repair.

Regards

Magman
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bill



Joined: Dec 10, 2009
Posts: 1
Location: New Zealand

PostPosted: Thu Dec 10, 2009 2:09 pm    Post subject: good place for buying keys Reply with quote  Mark this post and the followings unread

WD Greenhill - Nigel Greenhill [nigel@wdgreenhill.com] seems to have good supply of old keys - very helpful and quick with a technics problem I had
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MikeRobinson



Joined: Oct 16, 2014
Posts: 4
Location: Nashville, TN

PostPosted: Thu Oct 16, 2014 9:05 am    Post subject: Trying to clean Matrix-6 keyboard, but don't understand this Reply with quote  Mark this post and the followings unread

I am trying to disassemble a Matrix-6 keyboard and I stumbled-upon this thread, where the OP succeeds in doing it. However, I do not quite understand the description. I don't know what he means by "spreading <<something>> slightly apart ..." And I'm of-course reluctant to "spread" anything that's fairly irreplaceable and made of plastic.

(I managed to loosen the spring so the key now flops, but not to remove the key.)

It looks like this intended to be "very easy to do." The key is cleverly mounted so that you can pull it backward such that the notches in the back of the key (shown in the photo just above the left end of the tape-measure ... about 1/8" long they run parallel to the tape in the photo) a-l-m-o-s-t line-up with the edge of the metal frame. It seems intuitive to me that this "ought to be a wonderful invention," that would enable the key to be removed exceptionally easily, even "on the road," just by pulling it back and then prying it out. But this doesn't q-u-i-t-e release the key.

(Unhooking the spring simply keeps the key from springing back up, of course, but it doesn't release the key.)

Can someone who has one of these marvelous synths show me exactly how to remove the keys without breaking them? (Dang it... keyboard keys ought to to be "easy to remove." These look like they were designed to be "easy to remove.")

An e-mail ("miker@sundialservices.com") would be very helpful as I'd like to clean this keyboard.
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MikeRobinson



Joined: Oct 16, 2014
Posts: 4
Location: Nashville, TN

PostPosted: Thu Oct 16, 2014 9:48 am    Post subject: A small update ... Reply with quote  Mark this post and the followings unread

Well, so far, and with the unfortunate side-effect of having broken one key, I have determined that the keyboard's design is clever. The notches in the back of the key, instead of being "slightly too long," are not. If you fully pull back and then depress the key, the key can be pried out with a flathead screwdriver placed underneath the rear of the key.

I'm not too keen on "prying things," though. Still exploring to see how this thing was made.

Edit: "Oh, damn, this thing is genius-clever!" I figured it out and now I'm gonna try to explain it real good. Smile

You can see from the photo that the rear end of the key has two vertical tabs, on the left and the right-hand sides. When the key is in place, these two tabs straddle the piece of metal that lies in-between the holes that the tabs drop into. What you can't see from the photo is: exactly how that's done. If you successfully remove a key and look at it from the back end, however, you will notice that the two tabs aforementioned are slightly tapered outwards. The horizontal slot that you can see, actually wraps around to the inside between the two tabs, and the taper fans outward just below it.

So, when you replace a key, you press gently downward on it, causing the two tabs to spread ever-so-slightly apart (because of the taper), then to "click!" into place.

To remove a key, then:
  • Pull the key backward.
  • Push the key down.
  • Now, put the flat blade of a screwdriver between the two tabs at the back of the key.
  • Gently twist the screwdriver to spread the two tabs slightly apart ... a couple millimeters will do it.
  • When the two tabs are spread wide enough to clear the slot (which is on the inside, between the two tabs ...), such that it is no longer gripping the piece of metal that lies between them, the key will now "rotate" up and out of the slot as you continue to push down on the key.


The spring is a curved piece of metal with a "bent" tab on one end and the other end that is straight (very slightly notched). The straight end is placed downward into a hole on the board. When the key is replaced, the bent-tab will fit neatly into a small indention on the underside of the key.

Once you understand the "trick," it's a very field-replaceable design.

Too bad I had to break one to figure out the trick.
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MikeRobinson



Joined: Oct 16, 2014
Posts: 4
Location: Nashville, TN

PostPosted: Thu Jul 09, 2015 7:57 pm    Post subject:  Final wrap-up: the project's done
Subject description: Here's the final details from painful experience . . .
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My keyboard's fully repaired and back in service. ("Ewwww..." the insides of a keyboard are messy! There is ... something ... growing ... on ... that ... circuit board. Shocked )

(1) The best tool for gently removing the keys is a painter's church-key. Get one with a nice, wide blade if you can. Some keys are too close to a transformer to allow a screwdriver. Pull back on the key, put the church-key in the slot at an angle, and gently(!) turn the church-key vertical, spreading the plastic tabs. With a little luck, the rear edge of the key will slide right up and out. Pick up the spring now and put it in the "springs bag."

(2) "LocTite Gel Control Super-Glue." Yeah, you're gonna break some. Carefully, carefully scoop up all the plastic bits into a ziploc bag. This glue is amazing because, a month or more after I bought it, it still hasn't turned into a solid lump of plastic like most super-glue containers promptly do. It is also, as the name implies, gelatinous. The repairs were as strong as the key itself, so I had no difficulty with the "repaired" keys. Whew.

(3) There are an amazing number of screws in this thing, but it was certainly designed for a factory: everything fits in exactly one way in exactly one place. Don't lose a single one. A big bag of ziploc bags, and a few plastic screw-top jars that delicious ice-cream comes in, should be staples.

(4) The best contact-cleaner is Everclear, a 200-proof pure grain alcohol (PGA) that, of course, can only be bought in a liquor store. All you need is a "miniature," containing a few ounces of product. The advantage of PGA is that it contains almost no water: when it evaporates, there's nothing left. However, denatured alcohol (paint store), and a big box of Q-Tips cotton swabs, will also do.

Caution: EverClear is both flammable and toxic. Resist any temptation to drink the stuff. Confused

(4a) A "universal cleaning spray" that I use all the time is actually homemade. It consists of a small amount of denatured alcohol in water, with a few drops of automatic dishwashing liquid soap and a squirt of "Jet Dry" dishwasher rinse-agent. Because of the alcohol it is anti-microbial, and a good cleaner. Don't use it on circuit boards. I use it all around the kitchen. I used it to clean each key after removing it.

(5) Notice how the spring fits below the key. The straight end is slightly notched and this fits exactly into a notch on the metal plate beneath the keyboard. To reattach a key, position the spring, slide the the key in from the front so that the plastic tab at the bottom slides under the lower plate, and set the key over the spring: amazingly, the spring won't fly away. Pull back on the key, press gently on the rear edge ... *click!* Insert the black key before placing the white key(s) beside it. Notice that every key is numbered with the letter of the note, and that one "C" at one end of the keyboard is slightly wider than all the other "C"s.

(6) The keys press down on a row of plastic cups that completes a circuit on the board below. This board was very dirty, and somehow, one of the screws that held the board in place had rusted in place. (I had to get very brutal with that screw ... may it rest in peace.) Amazingly, the plastic cups in strips that, once again, fit back in only one way. ("Made to be assembled in a factory.")

(7) Put your phone camera to good use. Take plenty of pictures at each step. When photographing things inside the case, such as exactly how the circuit boards under the keyboard fit, put a wooden ruler in the shot.

And, finally: "don't be afraid to do it." Cool You'll learn a lot about how your "favorite axe" is put together. You'll know how to service it. And, when you see first-hand just how dirty it gets, you'll put a cover over it.
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