ARC ref 110 tube bias prob

All is going well but the last two tubes (master and slave) are showing weird readings.

The master shows no reading and reading 16.76 volts DC (not 0.65mVDC!) on my Fluke. The slave is showing a negative rating (-20mVDC).

The tubes are all good (swapped them over) but any tubes in that position do the same.

Anyone know what’s going on?

willmarchant11-14-2022 5:24pm

ghdprentice Details Discussions Posts This discussion Message User 9,499 posts 11-14-2022 at 05:33pm Copy Comment URL Report Comment Edit Delete I would call audio research. In the past I have done this and talked with… the tech. Or email. But calling is quicker.
jjss49 Details Discussions Posts This discussion Message User 6,926 posts 11-15-2022 at 01:01am Copy Comment URL Report Comment Edit Delete i have that amp, is that particular one new to you? seems like when the last set of power tubes went (perhaps in the hands of the prior owner), they took out a biasing resistor in that quadrant, which will likely require the amp traveling back to minnesota
fsonicsmith Details Discussions Posts This discussion Message User 995 posts 11-15-2022 at 02:02am Copy Comment URL Report Comment Edit Delete Yeah, I know I lent you my 2 cents in your original thread but I was wrong. I think only a circuit problem like the above referenced resistor could explain your Fluke reading.
immatthewj Details Discussions Posts This discussion 3,300 posts 11-15-2022 at 04:28am Copy Comment URL Report Comment Edit Delete @jjss49 , I used to have a pair of ARC VTM120s that would take out grid resistors on the CB enough that I got proficient at replacing them. Is this biasing resistor in a difficult location to get to, or might it be something that OP could de-solder & then solder a new one in (instead of shipping it back to Mn)?