Vintage Synth Repair

I did not do the PS mod yet -- that's probably a smart place to start.

You should be able to test the 50240 by plugging a cable into an amp and simply clamping a cable's sleeve to the Omni's ground and touching the tip to the outputs of the 50240.  So you noted the pin outputs are in the audio range so you should hear them -- I was certainly able to.

Note that it's a pretty high vpp level coming off the chip, so don't turn your amp up before you plug in.  :)

Also, note that FlatKeys makes a replacement chip -- the FK50240 (http://www.flatkeys.co.uk/MK50240.html).  It's about as pricy as a NOS chip, but if I have to buy another one that's what I'll be getting... at least you know that'll work out of the box.  :/