[sdiy] dead CEM chips?

[john mahoney]

Edward,
It seems highly unlikely that all 12 CEM chips would fail simultaneously.
I'll bet that all the 4000-series CMOS chips have died. (Just kidding! That
was a previous thread.)

Seems like something shared by all the voices has failed, like an output
amp, the keyboard, the CPU, etc.

Is it sending MIDI data correctly? That requires a working keyboard and CPU,
and suggests a problem with the sound generation circuits.

Does it respond to MIDI data? If so, your keyboard's dead for some reason
(but at least the voices work!).

Check for different types of signals throughout the circuit when you press
keys. Are control signals getting to the inputs of the CEM chips? Check the
VCO chip outputs directly, using test leads; they should each be making
sound (depending on number of keys pressed, of course).

Good luck, hope this helps..
--
john


----- Original Message ----- 
From: <Ordeish at aol.com>

> Hi all. I was wodering how I can tell if the curtis chips are dead in my
chroma polaris. I know they have 12 chips all together and the synth makes
no sound. It does power up, and I can hear noise in the output. THe volume
lever works to raise and lower the noise level, so I think that part works.
There just is no sound. Oh its a Chroma Polaris.
>
> thanks
>
> edward