Electronic Repair

In 2023, two different Roland Jupiter 4’s came in for repair around the same time, and both were in almost mint cosmetic shape. The first Jupiter had an envelope problem with the VCF of one voice, and a faulty power switch. I replaced a 4016 chip to fix that voice's envelope, and I was able to source a brand new power switch. I also recapped the power supply.

The second Jupiter 4 was purchased from the Netherlands, and ran on 220VAC. To address the voltage difference for United States 120VAC, my client purchased a Synthronics switch mode power supply for me to install. Unfortunately, the power supply was DOA and had to go back to Germany. After that was sorted out, the next major problem was with the bank of interlocking preset switches on the right side of the instrument. The switches wouldn’t always disengage, and that caused them to jam right up! When that happens, none of the switches will latch.

First, the faulty switch bank had to be removed. That looked like a puzzle to get them out because one of the mounting screws isn’t accessible from inside. To get to that screw, one of the plastic switch covers on the front has to be removed in the middle of the bank. The problem had to do with some of the the switches moving too slowly when disengaging. The preset bank is actually two banks linked together, so a little more complex than the single switch bank on the left side. To work correctly, the switches have to be quick, and disengage right before the next selected switch engages. If they conflict, no switches will lock in, and you might as well dispose of the instrument. I’m just kidding. After a good cleaning, and lubrication, all the switches locked and unlocked perfectly. I also changed out the dust gaskets on all the faders, and gave each control a good cleaning.