Pin 4 of the 829B is the cathode. Follow the wire connected to pin 4 to see if it is grounded or if it connects to a cathode resistor. If it has a cathode resistor is is self bias. If not you will need to draw out the bias supply to determine how to set the bias.
Thanks for reply, but no autobias, Amp is in past being serviced and R is left behind.
Powertransformer is replaced and has been recapt years ago.
Amp has 4 potmeters, 3 are close to 829b socket numbered 2,3,and 4 and one next to the output transformer looking like a brass nut with a screw inside.
I cant find a scematic and don't want to dismantle the amp to findout what is what.
Powertransformer is replaced and has been recapt years ago.
Amp has 4 potmeters, 3 are close to 829b socket numbered 2,3,and 4 and one next to the output transformer looking like a brass nut with a screw inside.
I cant find a scematic and don't want to dismantle the amp to findout what is what.
Likely only 2 of those 4 pots are bias, the others must be for something else like AC/DC balance in the driver stage.
You really need more information before you attempt to adjust anything.
It's important to get the plate currents to match fairly closely in PP amps and the 829B often exhibits significant differences between the sections and tube to tube. (I have an Audio Romy 829B PP stereo amp that I used from time to time)
You really need more information before you attempt to adjust anything.
It's important to get the plate currents to match fairly closely in PP amps and the 829B often exhibits significant differences between the sections and tube to tube. (I have an Audio Romy 829B PP stereo amp that I used from time to time)
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