Roland JX-3P Sound Switching problems

[KittenSmoothie]

Hello! This is my first synth. I got this Roland JX-3P in pristine condition. When I first played it a few months ago, I could switch through channels A and B just fine, but not C and D. About an hour into playing the synth, I noticed I couldn't switch from channel B (the channel I was playing in) to any of the other channels. I also couldn't use the chorus, hold, or mute buttons. I turned the JX-3P off and fired it up again. When I did this, I couldn't switch to any channel except for channel A and C (I could access was channel C by pressing the "write" button, but when I did this, I couldn't switch back to A without turning the synth off). I still couldn't use the chorus, hold, or mute buttons. All this has been going pretty much since I got it, until yesterday. I was writing sounds in channel C when somehow I pressed something that made it all go back to how it should be. I had no trouble switching sounds or using any buttons. It was all fine and dandy until about an hour, when it went back to how it's been. Now I'm back to just using channel A and sometimes C. It has been a very frustrating experience. Anyone know what I'm doing wrong? Thank you so much for the help.

[rhino]

Welcome to the board!

First, open the lid and check ALL cable connectors. There are two that go directly between the main board and the panel button board.

Next guess would be an intermitant problem with IC 34... scans the ABCD column of buttons.

[KittenSmoothie]

Welcome to the board!

First, open the lid and check ALL cable connectors. There are two that go directly between the main board and the panel button board.

Next guess would be an intermitant problem with IC 34... scans the ABCD column of buttons.

Hey, Bill!
Thanks for the tip. I opened up the synth, but all the wires are connected properly, and there seems to be nothing wrong with IC 34.

[rhino]

OK, but IC chips almost never have any external signs of failure. You will need a 'scope and/or logic probe at least.