Quote Originally Posted by mnow View Post
The outputs of IC 22 - 27 on the CPU board all produce a signal and change in frequency as keys are pressed. The data channels all seem to be working but the CSWR pins all have just a high signal (I.E. no data being sent).
IC 15 - 16 seem to operate differently (the chip select decoders). IC 16 has some form of clock data on it's output while IC 15 just has high output. Have swapped the chips, but still no go! Any idea why the POP chips (IC22 - 27) are outputting
signal?
After re-reading the manual, it is starting to look more like the PIC chips in the INTERFACE circuit are not controlling the keyer circuits in the symph circuit!
Correct me if I am wrong, but it seems like the POP chips always output signal, and is is the function of the PIC chips to turn the sound on or off?