1176 GR not working

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

lucstm

New member
Joined
Dec 21, 2012
Messages
4
I'm building my first 1176 rev G and I'm encountering some issues. The signal goes from the input to the output and both knobs seem to be working fine. However, the bias adjustment doesn't have any effect on the signal level. I've double and triple checked the wiring, components as well as read the forum but I'm stuck. Can anyone help? Many thanks.
 
lucstm said:
The signal goes from the input to the output and both knobs seem to be working fine. However, the bias adjustment doesn't have any effect on the signal level. I've double and triple checked the wiring, components as well as read the forum but I'm stuck.

I can't help you as much as the experienced users here. 

Does this mean to say you are hearing audio (attenuating or otherwise), only your vu meter is not responding to Q bias adjustments? 

From what I have learned through others troubleshooting their issues on the Rev A thread, it could very well be that you have misplaced/wired something incorrectly.  Did you check with a DMM each component was working prior to filling your PCB, as advised? 

Additionally the Q bias is fragile - too many turns in either direction can render it disposable.  Have you been 'heavy-handed'? 

Have you checked voltages, relative to the revision against Mnat'?

All the best.  ;D
 
I probably need to check the voltages then. Where can I find the procedure to do that?
 
lucstm said:
I probably need to check the voltages then. Where can I find the procedure to do that?

Check the DC voltage at the gate of Q1 while turning your qbias pot.  You should see a negative voltage that changes with the pot rotation.

Mike
 
Back
Top