mercredi 29 octobre 2014

JX3p with issues, any ideas?

I recently picked up a long neglected JX3p with several issues that I have been working through. It had one ir3109 vcf chip removed, so it only plays voices one through five with the sixth not sounding. Some patches worked fine and others sounded really messed up.



After moving the single remaning fader from the brilliance to the edit slot I was able to determine what was going on.



It seems almost everything works as it should except for the dco's. It seems like the square wave works on both dco 1 and dco 2 for all voices. This is where it gets strange, the saw and the pulse wave work on some voices and not on others, for dco1, voices 3 and 5 work and for dco2 voices 1,2, and 4 work.



So essentially every single voice has something wrong. The oscillators that don't work all produce the same tone, which is a buzzy F note.



This thing was literally in pieces when I got it, no keys in the keybed, no conductive rubber strips, missing every screw, so just to have it in a place that resembles a keyboard, a really beat up one, is great. I just want to see this baby pull through all the way.



Something to note, when the filter chip was removed they didn't do a very clean job, a couple of the pads have been peeled off of the board. Lots of white residue around most of the resistors.



I hope someone has some insight so I can get this JX going again. Any information or suggestions is greatly appreciated, thanks!





JX3p with issues, any ideas?

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