From tyrone_topheavy@yahoo.com Thu Oct 30 22:42:55 2008
Subject:Re: Kinda OT: Servicing keybeds

I've done about 1/2 dozen keybeds, and they all work about the same.
 
You'll have a PC board with contacts and solder traces and diodes (diode matrtix) and rubber strips with contacts in them also. When you depress the key, the contact(s) in the rubber boot makes contact with the PCB and tells the CPU a note on of off event has happened, as well as velocity which is calculated by the time it takes between the first contact and the second contact being closed.
 
A good "take it apart, clean it, and put it back together" usually suffices. Take your time, and use a digital camera to keep track of which connectors you might have to unhook. If there are any mechanical probelms, they'll be evident at this point.
 
"Stage two" might include de-oxidizing the contacts on the PCB using a rubber eraser.
 
As a last resort, one or more of the rubber strips might have to be replaced, you may have some bad diodes, or a broken/cold solder trace or bad ribbon cable going to the CPU.
 
A normal take it apart and put it back together takes me a couple of hours. Of course, this includes giving all the keys a soapy water bath, hand dry, and re-assembly. If troubleshooting is involved, it can take longer.
 
Funny story, I just got the keybed on a JX-3P back together. It required ALL of the above and them some. The funny part is that I had put the springs in a paper coffee cup so I wouldn't lose them , and later threw it in the trash. So, I ended up makng 61 new key springs from 2 pieces of 21" long pre coiled spring stock. Count 10 coils, stretch, cut, and make a loop on each end using needle nose X 61 !!! It plays wonderfully now.

--- On Thu, 10/30/08, Ryan Stroup wrote:

From: Ryan Stroup
Subject: [CWSG] Kinda OT: Servicing keybeds
To: CloneWheel@yahoogroups.com
Date: Thursday, October 30, 2008, 9:57 PM

Hey guys,

My apologies in advance for the off topic thread.

I have a Roland RD-300s digital piano (an old 1986 model) and recently
two keys have suddenly decided to stop working. Sometimes they will work
intermittently but most of the time they won't work at all. Naturally,
they are in the range where I play the most. I can't seem to find any
kind of service manual (which doesn't surprise me) so I'm turning to you
all. Has anyone had this problem with their boards and how did you fix
it? I'm hoping that the procedure to gaining access to the key contacts
will, at the very least, be similar.

Thanks!

--
Ryan




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