Hi
I got a c1000 pre used and it has an issue. When I have the pre (and the amp) powered on, if I play one source (e.g. CD) it works fine and sounds good. However, when I switch to another device, e.g tape, there is a load hum sound that last one second. This happens everytime when I switch any device. Also the sound becomes louder or softer along with the volumen control (loader when volume is up). I changed muting transistors to try to fix but it does the same. I suspect it related to a bad component going to the mute function on the system control IC (pin 16 on the oIC6 on the schematic, see attached image) but I have no clue. Any suggestion for troubleshooting is welcomed.
I got a c1000 pre used and it has an issue. When I have the pre (and the amp) powered on, if I play one source (e.g. CD) it works fine and sounds good. However, when I switch to another device, e.g tape, there is a load hum sound that last one second. This happens everytime when I switch any device. Also the sound becomes louder or softer along with the volumen control (loader when volume is up). I changed muting transistors to try to fix but it does the same. I suspect it related to a bad component going to the mute function on the system control IC (pin 16 on the oIC6 on the schematic, see attached image) but I have no clue. Any suggestion for troubleshooting is welcomed.
