Thank you very much Alec for helping me fix my Polysix via video link.

During our video chat we worked out that the Spark Killer had blown, although this was not responsible for the synth not powering up. Then we tested the Kiwisix power supply, and as Florian had also suggested the other day, to check the +15 +5 -5 & -15 volt test points. These were all showing 0 volts. And then with Alec's suggestion, we checked the 2 fuses on the Kiwisix PSU, and I realised rather foolishly that I hadnt checked those. And surprise surprise, they were both blown....DOH!!!

So today I removed the spark killer on the KLM-425, and replaced the blown fuses on the Kiwisix PSU.

This still did not explain why my synth died the other day. So I decided to investigate what I had done that day. After the Polysix died, I removed most of the ground wires  but had one ground wire left on the KLM-368 FX board. But this was soldered correctly, so I rechecked where I had done a couple of small mods, including the LPF bypass mod and Saw & PW mod on KLM-366. These also looked fine, but as I  was putting the FX board back I noticed I had replaced IC12 the wrong way round. I then remembered, when I was doing the LPF bypass mod, a little solder had flicked on to the IC socket of IC, which I had added recently replaced. I had removed the chip so I could remove the solder more easily but in my rush I had put it back the wrong way around. "What a prat" I thought to myself :) I re socketed it the correct way around, turned on the synth, and success. Everything working again as normal.

Comparing the Polysix schematics for IC12 with the datasheet for that IC, I can see that having it installed the wrong way around, would have meant some inputs would have been connected to outputs and vice versa. What a stupid mistake.

So there you go. Lesson learned. Always double check what you do, and dont be in a rush. I have only connected the ground from KLM-368 FX board to the Kiwisix PSU and left the others off for now, but the noise floor is around -70db, so I am not sure if its worth bothering with the others as described on page 27 of the Kiwisix Manual v4.2. Will adding the others reduce the noise floor, or is that similar to what others are getting?

So once again many thanks to Alec, and thanks also to Florian for his suggestions.

Cheers