Infinity Overture 2 amp signal path question

[byoungblood]

I am trying to troubleshoot this amplifier in this powered speaker. I understand the signal path to the 2N3906 Q6, but I am a bit lost between there and the bases of Q10 and Q12.

Is R63 a feedback path from the output?

Also, the bias is supposed to be adjusted via POT2. I can turn it fully in each direction but there is no change to the bias of any of the 4 output MOSFETS. There is supposed to be about 5.9mV dropped across R77 on the source lead of Q13, but I only measure 5.0mV (not off by much) but the potentiometer has no impact on the bias of the MOSFETS at all.

Thanks in advance.

[velixzeen]

Hello byb, just read your post about the O2 amp.  Any luck figuring out the cct and o/p path?  I have a pair of O3 speakers and they use the same amp judging from the schematic you posted.  I'm looking for information and noted you had a spec of 5.9mV drop on R77.  Where did you get that value?  Can you post a link or something?

Like you I wondered about the path IN to OUT on this.  I hope the schematic is accurate.  Perhaps one could throw this into multisim and simulate it? 

Does turning the POT2 move the bias of Q11, the 2SD2012?