Blackstar HT CLUB 40 Bias Circuit Problem

[Khefer Kaos]

Hi guys!

I have some issues with the HT CLUB 40 bias circuit. Apparently all is working, but the BIAS_ON signal in not present. I check voltages and apparently find the problem on pin 23 of IC10 (PIC16F57 microcontroller) where the BIAS_CNTRL signal is missing.

Supposedly, BIAS_CNTRL go to IC16 TL072 comparator opamp and then, BIAS_ON signal go to the bias circuit and On this.

Will the PIC be damaged? .HEX problem?

Thanks in advanced.

[g1]

Here's the schematic.
Is this one of the blackstars where bias is shut down if nothing is plugged into the input? If it seems to work fine, that is probably it.
Edit: see pin 14 of IC10, connects to input jack

[Khefer Kaos]

Here's the schematic.
Is this one of the blackstars where bias is shut down if nothing is plugged into the input? If it seems to work fine, that is probably it.
Edit: see pin 14 of IC10, connects to input jack

Yep, it's one of this.
Guitar cable are plugged when I do the measures. All other things are present, but only the BIAS_CNTRL isn't.
Thanks for the schems...

[Enzo]

What are you expecting to be there but not finding? All you have said so far is it isn't there. What isn't there?

What I see is a bias feed that sits at max voltage, the coldest setting if not in cutoff. Then BIAS_ON turns on TR4, completing the voltage divider circuit path to ground.

I expect some negative voltage on BIAS_ON.

I have no idea what goes on in the PIC. There could be direct control from the input jack, or the jack might only work MUTE. I would suspect the speaker jacks to control this bias circuit somehow though.

[mikeskory]

Did you ever get this working. I'm working on a Soloist 60 which appears to be the same as a Club 40. Dead ended at the IC10 PIC16F57.