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please help me resurrect my roland JX-3P! Keyboard Synthesizers
Old 15th January 2012
  #1
Gear interested
 

Thread Starter
please help me resurrect my roland JX-3P!

I have an old JX-3P that I have been attempting to fix for a week now. When i first got the machine it had no functionality and made a tone that resembled stuck midi.

Then it died.

I assumed that the initial problem was power related and found a bad bridge rectifier. I put in new components and measured stable voltage rails on the output of the power supply board!!!!

I connected the main PCB and the control/panel PCB and measured stable voltage rails from multiple connections. With a new confidence i hooked up the entire thing, plugged it in and BLEW the 15V rail fuses!!!

I got more fuses and put it together piece by piece checking voltages and found a short (it exploded) in the jack board. seems I have a bad footswitch jack.

I have yet to replace this part but stubbornly refuse to give up!

So these are the questions I have:
1. should I see any LED switch functionality? the only thing that seems to operate is the LFO switch.

2. does the unit require a full reassembly for visible functionality?

3. would the short at the jack board cause functional failure? or is this indicative of a larger problem?

4. owners of JX-3P's, what should i see on startup to identify normal operation?

5. does the battery have to be in line for the unit to function at all? It died and was not inline during my tests.


I have not attempted to listen to the output of the machine yet. I want to see and control it before going there.

This is a FANTASTIC site for old synth service manuals
(in case you didn't know!!)SYNTHESIZER SERVICE MANUALS

This is the link to the JX-3P service documents that i have been referencing.
http://www.synfo.nl/servicemanuals/R...VICE_NOTES.pdf


Thank in advance for any help you can offer.
I WILL GET THIS THING MAKING NOISE!!!!
(with your help of course )

-Nate
Old 15th January 2012
  #2
Lives for gear
 
acreil's Avatar
 

Quote:
Originally Posted by epicnate View Post
I got more fuses and put it together piece by piece checking voltages and found a short (it exploded) in the jack board. seems I have a bad footswitch jack.
This part doesn't make any sense to me. Look at the schematic, it has nothing to do with the jack. and that part of the circuit shouldn't have anything to do with the 15V supply. You probably connected something wrong.
Old 15th January 2012
  #3
Lives for gear
 
alexp's Avatar
I agree with acriel. Make sure on reassembly, everything goes back in the same order, facing the same direction as it was removed. You have to be dilligent as well when soldering that your not lifting traces or anything.

It sounds like a total power supply failure though man. Could be time for a rebuild. It seems your PS can spit out stable voltage with no load put on it, but as soon as theres a load applied, it pops. Let me do some research and see what I can pull out of a hat for you.


alexP
Old 15th January 2012
  #4
digital ears love analog
 
Rogue Ai's Avatar
Quote:
Originally Posted by epicnate View Post
4. owners of JX-3P's, what should i see on startup to identify normal operation?
Bank A, button 1 and the chorus leds should be lit.
Old 16th January 2012
  #5
Gear interested
 

Thread Starter
Thanks for the replys guys. Your absolutely right Acreil. No 15V going to hold pedal.
I checked the caps on the board and they seem fine too. I will check the PS board under load. Good call.
Not seeing any of those LED's yet. Checked the switch and LED matricies and the IC's and traces appear un-damaged.

I'll report my findings tonight when I get home.
Old 31st October 2012
  #6
hey

i got a jx-3p that powers on, everything works, then it powers off for no reason, powering back on a few moments later.

i replaced all the capacitors in the power supply, and it still happens.

anybody have any ideas? I'm stumped.
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