Saturday, 18 June 2011

Roland Jupiter 8 Power Suppy recap

The hot synth of the moment is the Roland Jupiter 8 and the prices people are paying for these in recent times is bordering on crazy... My client has owned his for nearly 10 years and it is in good condition but in need of a bit of TLC to keep it running smoothly for another 30 years. Today we will cover the recapping of the power supply. This is a good starting point for any repairs on a Jupiter 8 or any other vintage synth for that matter. I would strongly recommend doing this before attempting to fix any other issues you have with your synth. Most of the capacitors i removed during this repair are now at less than half their rated capacitance. Pretty good for their age, but still - not good enough for reliable operation.

Warning: Any advice given is free and there are no guarantees or warranties implied. Take care when working with mains voltage- one flash and you're ash.

I will be making a parts kit available soon for a very reasonable sum. I have used Nichicon VZ, Panasonic FC and Elna Slimic II - these are pretty much the best quality caps you can buy. Don't use cheap Kung-Fu parts.

Capacitors required:
3x 6800uf 35v  (C1, C7, C11)

2x 220uf 16v (C9, C14)
2x 100uf 25v (C8, C12)

1x 100uf 16v (C15)
2x 10uf 16v (C3, C6)
1x 1uf 50v (C13)

This is the board in question.

1. Remove all screws holding the PSU board to the case (5 screws, Phillips head)
2. Mark connectors attached to adjacent boards with a marker pen (U for Upper, L for Lower) (4 connectors) - this is so you know where to put them later :) - You could also take a high resolution photograph of the inside, but it pays to do both - just to be sure.

3. If you have a MIDI kit (such as the Kenton kit installed in this particular JP8) you will also need to mark the cables so you know where they go (rainbow cable from Jupiter 8 and grey ribbon cables from MIDI kit - pictured above)

4. In some cases there may be some cable ties holding the cables in a bunch. Use some wire cutters and cut this off very carefully - you DO NOT want to cut through your wiring. If you do, don't say i didn't warn you.

5. Carefully lift the power supply board out of the Jupiter 8 - hold onto the board, not the big capacitors. If it's not coming easily, double check that you have loosened all the wiring looms sufficiently.

6. Move the PSU board to a position where it will be comfortable for you to desolder the capacitors.

7. Desolder the three large capacitors first. I found that it helped to add a little solder to the joint first (improves heat transfer) and then use 3mm wide wick to soak everything up. My desoldering station is currently in Spain getting repaired so it's back to oldschool methods for a while. The capacitors are glued to the board with some brown coloured goop that comes off quite easily with a bit of a wiggle. Once you have removed each capacitor, put them aside and maybe use a desoldering vacuum to clean out the holes.

8. Now, BEFORE you go soldering in the big capacitors - work through the other, smaller capacitors first. You will be soldering those in last.

 9. It's a very good idea to mark the circuit board with the polarity of the capacitor before removing it. It is already marked (circle with white "notch" - the notch is for the -ve/negative side of the capacitor) though writing a + or - with a marker pen might work better for you. The LONG lead of the capacitor is your +/positive side.

10. Starting at the back of the PCB, work through the other capacitors one by one. Clip the leads as you go (high quality side cutters are ideal), ensure the leftover capacitor leads do not end up floating around your synth.

11. Double check to ensure you have put all the capacitors in the right way.

12. Start soldering in the 6800uf capacitors - Negative lead/white stripe faces to the front of the synth. Start at the rear capacitor and work your way forward.

13. Check your work AGAIN and then re-install the PCB into the synth, connect all cables ready for testing.

14. You should have something looking like this. Check your wiring again to ensure everything is connected correctly.

15. Calibrate your PSU after leaving the Jupiter 8 on for 30-60 minutes (lid closed to keep the heat in). The information can be found in the service manual but i will include it below for your convenience. Use the best multimeter you can get your hands on. Fluke and Tektronix are both great, however expensive (maybe ask a friend?) I like to use a Vishay/Spectrol trimmer stick (yellow thing in above picture) to avoid shorting anything out. A wise $5 investment

Saturday, 4 June 2011


So, i have decided to start writing a blog to document the repairs i do. Many of the pieces of gear i work on are more than 30 years old and are in need of a bit of TLC. Hopefully this blog is able to help other synth owners around the world maintain and keep their vintage gear running and producing great music for many years to come.