On Jul 15, 5:00 am, "Eric" wrote:
Hi,

My B&K 1211A color pattern generator is defective. I can not adjust the
channel A and Channel B and chroma frequencies. As long as I disconnect the
variable capacitor for channel B, the channel A and chroma frequencies can
adjust to the specific values. If I re-connect the variable capacitor, the
unit not working anymore. I change the variable capacitor for channel B but
still act same. If anyone in this news group has the schematic or any ideas
for troubleshooting. All the TTL IC have been test and ok and switches all
fine.

Thanks

Maybe the variable capacitor is shorted. Have you measured the
resistance from one terminal to the other with at least one terminal
disconnected from ecerything else. You should have infinitely high
resistance.

H. R. (Bob) Hofmann