Should I buy a synth with a key out?

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madmarkmagee
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Should I buy a synth with a key out?

Post by madmarkmagee » Tue Feb 15, 2011 8:23 am

I'm looking on ebay at a Roland JX 3P. Apparently its in working condition apart from the 8th key from the left "not triggering". I think i can probs win it for 360 AUS. (doesn't come with pg-200, should be able to get it else ware though(i can actually get that posted) It is good because its in my local area. Their isn't much close to where I live. How hard do u guyz and girlz think it would be to fix the key? what are the chances its just a mechanical problem and easy to fix or a problem with a chip or circuit?

smoothcriminal
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Re: Should I buy a synth with a key out?

Post by smoothcriminal » Tue Feb 15, 2011 8:25 am

If it's only 1 dead key, it's probably a bad contact and therefore a comparatively simple mechanical problem. But someone with more technical expertise should probably give you a second opinion.

Wish I Could Play
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Re: Should I buy a synth with a key out?

Post by Wish I Could Play » Tue Feb 15, 2011 10:53 am

I re-did all the keys on my JX-3P last week actually. The JX-3P is built like a tank, and it's probably a build up of dirt that's causing the contact to not trigger properly. I just fixed three dead keys on my own JX-3P, and here's how I did it:

1) Phillips screw driver
2) Pencil eraser (to clean up dirt/dust/whatever on the contact - if the contact is actually damaged, you're SOL).
3)Needle-nose pliers

Disassembly:
1) Identify the dead key.

2) Underneath the synth, there are a number of LARGE phillips pan-head screws (should be 6 or 8, can't remember exactly how many) at the front of the unit, directly under where the keyboard sits. These secure the keybed in the synth - remove them.

3) Now, move to the end-caps. There are 4 screws in the side panels (2 on each side) - remove all 4.

4) Back underneath the synth, there are a number of smaller screws running along the very back - remove all of them

5) Carefully lift the top panel off - if it feels like it's catching, it's most likely wiring - CAREFULLY work it free, and rest the top panel aside.

6) Unplug the two connectors running from the keyboard (take note of which clip goes where!), and carefully slide the keyboard out of the synth. Some say to remove the Voice board, but i didn't have to in mine.

7) Once the keybed is out, there's a small translucent plastic strip that runs the length of the keybed underneath. Very carefully peel this back until you reach your dead key - peel it past one more key after that.

8) carefully turn the keybed back over, and remove the spring from the dead key. Once the spring is removed, pull the key straight towards you and it should come out with little force - continue to remove all subsequent keys that sit on-top of the rubber contact strip.

9) After all the keys are removed, carefully pull the contact strip off of the PCB - exposing the PCB's contacts. Insect for damage, and if none is present, lightly rub the eraser on it (it should go from a dull appearance to more of a bright, shinny colour).

10) Reassemble in reverse order :)


If you did everything right, it'll work perfectly after that. I'm not a tech, but that's the entire process I did on mine. Shouldn't take longer then 30 minutes to do. I should also mention that if you play the key prior to fixing, it shouldn't work - however if you have to press really hard, or press near the top (case), and it makes a sound - it's a contact issue. If that's the case, do what I wrote above.

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