I have a trouble with my dynaco st-70 (triode elec ef86 driver board, the rest is stock) biasing, when I try to set bias on output tubes the weird thing happens - one channel reaches a maximum of 1.3v and the other channel stuck at 1.2-1.3v and doesn't change the bias voltage when I change the bias pot position.
I've checked all voltages and noted that the filament voltage on all of el-34 tubes is about 3.3v ac - half of it's normal voltage.
Could it be a wiring error? Transformer issue? What to check next?
I would appreciate any ideas, thanks!
The voltage at pins 5,6 of el-34 is about -45v
The voltage at pins 3,4 is about 445v.