GEM S3: replacing broken keys

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KJX Barry Warne
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GEM S3: replacing broken keys

Unread post by KJX Barry Warne »

hello fellow GEM S owners/players

I very recently purchased a 1992 GeneralMusic S3 ... with two broken keys. Very high D and D# ...and I just ordered replacements from Syntaur :)

Today I also (very carefully) opened up the S3, mostly so I could check the keyboard action and fish out broken pieces of the key plastic. When the parts arrive I know I have my work cut out for me during the installation.

Q: has anyone done this? I'd love to have a walk through.

If no one has .. then I'll become the forum expert :wink: and document the procedure here. Mostly the procedure will involve great care for an instrument nearly 30 years old. I did notice already that some of the glue that holds down the cables running between some circuit boards has expired. Not sure if I need to re-glue .. that glue seems to have held the cable to the metal chassis.

I also noticed a new kind of keybed for me: one that has a little extra spring under the key, not quite sure what that does but I do see that will be tricky to reconnect.

Anyway, thanks for any tips if you have them. I like this keyboard a lot already - so far it works well, including the #polyphonicaftertouch for which I already have great things in mind.

cheers ~ and stay safe!
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Last edited by KJX Barry Warne on Sun Apr 19, 2020 7:48 pm, edited 1 time in total.


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puremusic
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Re: GEM S3 replacing broken keys

Unread post by puremusic »

Even though I can't help with the GEM S3, I have to say, I really appreciate you photographing the process. It's great to see this sort of documentation of fixing and modifying a keyboard especially one as vintage as the GEM S3 with its rare polyat.


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Re: GEM S3 replacing broken keys

Unread post by KJX Barry Warne »

puremusic wrote: Mon Apr 13, 2020 7:30 am Even though I can't help with the GEM S3, I have to say, I really appreciate you photographing the process. It's great to see this sort of documentation of fixing and modifying a keyboard especially one as vintage as the GEM S3 with its rare polyat.

Cheers. I've done keys replacement before - usually a part of me finding a good deal in buying a synth. Have repaired a Microkorg, a Nord and a Yamaha. Those were straightforward mostly.

This GEM keyboard seems a little more complex. Well built. Some extra small linkages.


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Re: GEM S3 replacing broken keys

Unread post by puremusic »

Only done one keyboard open up and modification so far, but I do plan to do one or two more in the future. I did fix my Motif Rack ES too, it's great to get a good deal on a piece of gear due to minor issues like broken buttons.

Some of the fellows here know quite a bit about electronics.


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Re: GEM S3 replacing broken keys

Unread post by Saul »

I don't know how many of the GEM S3's were sold but I am guessing not huge numbers. It is one of those keyboards that pretty much flew under the radar and yet was actually amazingly good. I had often considered buying one but they don't come up very often. And when they do it is usually in a very poor state of repair.

So I think this is going to be one of those pioneering events where you have to lead the way in this repair Barry. And thanks so much for doing it ((i)) ((i)) ((i))


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KJX Barry Warne
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Re: GEM S3 replacing broken keys

Unread post by KJX Barry Warne »

Saul wrote: Mon Apr 13, 2020 12:23 pm So I think this is going to be one of those pioneering events where you have to lead the way in this repair Barry. And thanks so much for doing it ((i)) ((i)) ((i))
Happy to share. Always a DIY learning experience. Waiting for the new keys to arrive via post.

btw - does anyone know if it is possible to add RAM? Right now using the 3.5" disks as RAM but in reading the manual I see that there was an option(?) to buy 2mb of RAM?


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Re: GEM S3: replacing broken keys

Unread post by KJX Barry Warne »

OKAY!

Well it was a bit of a chore to replace the broken keys but now the job is done. And I have tips. Learn through me.

First of all, I can see why keyboardists might have stopped using these. They are great but repairs can be hair-pulling. The main contributor being the extra complication of an added spring under each key. I assume this is a release velocity spring?

Anyway.

Here goes.Be patient. Be careful. Take photos as you remove screws or ribbon cable connectors.

1) Lay the GEM S3 upside down on a soft sheet. Wife let me use the bed.
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2) Having a magnetic parts holder helps keep track of screws/bolts as they are removed.
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3) DO NOT remove the bolts that hold the keybed in place. Just remove the perimeter bolts around the edge.

4) carefully flip the GEM S3 rightside-up.

5) slowly slowly slowly open the top control panel and tip back against something like stacked-up towels.

6) undo the ribbon cable connectors so the upper control panel can be separated from the keyboard part of the chassis.
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7) turn the keyboard chassis around
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8) tip the keybed up so you can undo those bolts from the bottom. These hold the keybed down to the metal chassis.

9) working on the keybed, use thin pliers to lift up the spring at the back of the note you are replacing.
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8) generally what has happened is the under-key linkage has broken. These are the parts I ordered from Syntaur https://www.syntaur.com/keyboard.php?keyboard=1805. Inexpensive.
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9) the TRICKY part is affixing the replacement linkage to the BOTTOM spring. That spring is VERY VERY Fragile. I damaged one of these under the higest D note. Ugh. Replaced the damaged key, but now that note does not sound.
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10) reverse the instructions and test your work
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