Well, after a little more investigation I found the real problem with the Matrix 6. In fact, I should have found it right away but I guess I rushed past this. After checking the voltages again I noticed that the +12 volt regulator was actually outputting +18 volts. So with a little more help from my tech friend Joan, I got a replacement and new capacitors and fixed it. Now I have a perfectly working Matrix 6!
I also did some work on the Prophet 600. I replaced the sample and hold circuit capacitors and after all that work it turned out to be something else! That’s ok though because it should be done in old synths anyway. In fact, I’ll replace all the other capacitors eventually too. It turned out to be a lot more work on this synth though because the components are solders on both sides of the circuit board. That’s a pain! I could really use a teeny tiny soldering iron when working with such small components too! But another good learning experience.
Since the problem seems to go away after a warm up I suspected it was the oscillator chip so I got one out of my OB-8. Sure enough when I replaced voice one, oscillator 2 the problem went away. It still takes 30-45 minutes for the instrument to become stable so it’s really not a huge issue but there was definitely a difference so I will get a replacement soon.
Luckily they have just made up a new batch of the CEM 3340 oscillator chips so I will order a bunch so that I have spares for the P600 and the OB-8.
I still have to order a new battery for the P600 as well, but I think I will get a battery holder for it rather than having to solder it in. I’ll do that once I’m really to order parts for the CS-40m, which should be soon.
There may be another project soon as well. Soon we will know!