I just picked up a EH-0300 Vocoder but sadly the thing is faulty. Some pictures here:
http://www.clockworkrobot.com/vocoder/eh_vocoder.htm
Does anyone have schematics for it?

The unit fires up although the power light doesn’t come on. It makes a lot of buzzing sounds (I have disturbed the wasp nest inside probably) and the yellow ‘mic’ led
flashes on power up but no matter how you set the unit up or what sound signals you throw at it, it doesn’t change the sound.
It buzzes on with the bypass switches activated and only the standby switch makes it shut up.
I hope it’s just something simple with the power supply that’s faulty. Failing that it may be pre-amping of the sound signals?
I don’t imagine it’s something in the vocoder amps or filters themselves as that would be unlikely to have such wide spread effects? maybe?

Anyway if anyone could help me out with a schematic or any troubleshooting advice, that’d be great.
Thanks.