Very high bias, but no redplating...

[JubileeMan 2555]

Originally Posted by SatelliteAmps

Before anyone does any extra work that might not need to be done, I have to ask one more time. WHen you are measuring the mA on the tubes, one pair is coming up as 47mA per tube, meaning you are getting 94mA for the pair, and 118mA for the other pair at the same time, since this is a four tube amp. Correct? Because if you are getting 47mA for two tubes, and 59mA for the other two tubes, then the amp is not out of its range of bias.

The sixth post in this thread I answered your question.

Yes, the 47mA is from ONE TUBE and the 59mA is from ONE TUBE.

The bias King only meaures ONE tube at a time.

Originally Posted by ked

If you need more bias voltage you could build a bias supply like Marshall does and disregard the bias tap on the power transformer.

Ken

Not sure what you mean. I built a Marshall jtm45/100 and it has a tap on the power transformer. Is there a specific model you're talking about?

[ked]

Yes, look at the schematic for a Mdl. 1987 50 watt and others. They take the bias supply directly off of the high voltage secondary.

Ken

[JubileeMan 2555]

UPDATE:

Got some old RFT tubes, plugged them in and they were resting at 56mA! So I decided to get the soldering iron out.

I simply put a 1Meg pot between the 47k resistor and ground and it worked like a charm! Now I have a range of 35-55mA...

While I was in there, I replaced the 16+16uf cap and the 50+50 cap which were both original. I think I may have lost a little "mojo" by replacing these caps, but I need to be sure she's rock solid for gigging.

[Mattbedrock]

Good job. Glad you got her working. How about posting us a clip?