I was pretty upset the first time I discovered one of the keys on my
Kurzweil RG100SE electronic piano lying there, dead. I was happy when I discovered that it wasn't hard to
fix. But I was upset when it happened again a few years later and
I had forgotten how to get inside the case to fix it. If you've ever done these kinds of repairs, you know that opening the case without damaging it is often the hardest part. If you look on the back of the piano there's a lot of screws. If you look on the bottom, there's many, many more. If you just start randomly removing screws, you'll waste a lot of time, and you'll always have some extras after you've put it back together again. So here's how to get inside one of these pianos- and also some info on how the keys work. ![]() ![]() ![]() ![]() With all those screws out, (and the bottom three, of course), it should be possible to raise the front of the top- the edge that comes down over the backs of the keys- and tilt the top up into the position shown in the first picture. I didn't do this, exactly, because I took one end off completely when I was trying to figure out how it opened, before I discovered (well, re-discovered, actually) the three cheesy looking brackets deal. That middle bracket will drive you nuts if you don't know it's there... ![]() ![]() Putting the spring back on is a snap if you use a hemostat or a pair of needle-nose pliers. It's much better with the hemostat. The spring won't be as likely to spring loose while you're fiddling with it if it's clamped in a hemostat. Where in the world did I get these things? |
I tested some epoxy on the plastic. I could get a decent bond in shear,
so rather than attempt to glue the old piece back together I decided to attach a brace
to take the load. I pondered the break until I had a good idea of the area I had
to work with- then went looking for something to make a brace.![]() ![]() ![]() ![]() ![]() ![]() ![]() If this page has been helpful please consider contributing to my Steam Powered Studio. It's the world's first recording studio powered by listeners rather than by record companies or musicians. In return you'll get access to some great music, and you'll help insure that this page and more like it get made and maintained. |
This keyboard has sure kept me busy! In answer to some of the comments here, no, it isn't really a
weighted touch. It's better than most synths, in as much as the keys have little weights glued into them (so
maybe it really is a "weighted" touch?). They don't feel quite as insubstantial as a regular synth, but it doesn't
replicate the feel of real piano action. I've played some keyboards lately that really do well at that- but then,
I didn't like the sound of them as much as this thing. Not that it's perfect, by any means. I've begun to notice some distortion, some weird overtones, in the sound, but they don't detract from (and maybe they actually add to) the realism of it. Let me put it this way- I still get a lot of pleasure out of just sitting down and playing this keyboard after 20 years. I don't know of any other electronic keyboard I could say that about. Which is why I keep patching this thing up, rather than buy a new one. So. The latest problem was a long time coming. Years ago, before the last repair, my B below middle C key got weak. It would still sound, only it was not as loud as every other key. When I opened it up to fix that nasty crack I had a look at the mechanism of that key, but couldn't see anything wrong with it, so I left it be. Sometimes I do more damage just messing around with stuff than it's worth. Well, recently a strange thing happened. I completely lost the Eb above middle C key, while at the same time that B key fixed itself! This had to be related, but how? The keys operate like this- ![]() This is a side view of a key. Over there to the right, there are two "triggers" that stick down. These press down on two rubber "domes" when you press down the key. The inside of the domes have a conductive material in the top. This gets pressed onto conductive areas on a circuitboard and completes an electronic circuit, which the Kurzweil then registers as a key press. It's basically a switch, and is like the switches in a cell phone or TV changer. With one difference... There are two switches per key. This is how the Kurzweil determines how hard you strike the key. See, it doesn't literally measure the force you apply. What matters is how fast you hit it. The lightning-quick computer in the keyboard actually can tell the length of time between when the first switch makes contact and when the second one touches. It then calculates the speed of (and therefore, force on) the key and adjusts the volume of the note accordingly. Clever. Now, when the B key got weak, I sort of thought that one of these domes had cracked and wasn't making contact at the right time- therefore leading the keyboard "brain" to think that a heavy hit was a light hit. But the domes were both in good shape, and I didn't want to dis-assemble that part of the keyboard at the time. When the Eb key stopped working completely, I knew I had to get in there. A key that's a little quiet is "character". A key that doesn't work is "broken". ![]() ![]() ![]() You see a black dot inside the domes of the right? That's the conductive stuff that gets pressed down onto the black oval-shapes on the circuit board. It actually contacts two ovals, closing a circuit. If these get dirty, there can be problems... wait a minute! What's that there? ![]() How might it get in there? Well, the domes have holes in the sides of them to let air in and out when they are pressed down. This "pumping" action might have been the reason for the simultaneous "self-healing" of one key and failure of another- maybe that same little fleck of dirt got blown out of the B key and sucked up into the Eb key! Anyway, I carefully brushed all these contacts with a camel hair artists brush, then vacuumed out the inside of the keyboard after I had reassembled the rubber dome piece and contact board. Fixed! It's probably a good idea not to let your Kurzweil get too dirty. If this page has been helpful please consider contributing to my Steam Powered Studio. It's the world's first recording studio powered by listeners rather than by record companies or musicians. In return you'll get access to some great music, and you'll help insure that this page and more like it get made and maintained. |
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