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Channel B works great, very loud, Channel A is at about 1/10th of the volume. Tone is great but severely underpowered.
The only schematic I can find only shows Channel A, I assume(and from looking at the actual amp) both channels are the same
First thing I did was put all new 12ax7s and 6L6s in. No change.
Then I started looking at plate resistors. I replacde the v1 driver plate resistors, no change.
Then saw that for the phase inverter, which has 460VDC at that supply node, the plate with the 91K was only at something like 435VDC, and the 82K plate at 140VDC, so obviously way off. This is the channel A Phase Inverter.
I changed the 91K out, and 82K no change, and there's still the same wacky voltages on the plates. I've tried different tubes here.
Channel B PI voltages match the schematic A-OK
So what else could be causing the lack of voltage drop, and waaaay too much?
The channel B PI has proper 330V art the plates, and 76V at the Cathode . Channel A's cathode is 125V
Also, all voltage on the 6l6s are spot on, screens have good voltage, grids, etc
If it weren't for these wacky PI voltages, i would suspect something else, but this seems like a good place to start now.
Maybe the .1 couplers?
https://schematicheaven.net/boogieamps/boogie_5050.pdf
The only schematic I can find only shows Channel A, I assume(and from looking at the actual amp) both channels are the same
First thing I did was put all new 12ax7s and 6L6s in. No change.
Then I started looking at plate resistors. I replacde the v1 driver plate resistors, no change.
Then saw that for the phase inverter, which has 460VDC at that supply node, the plate with the 91K was only at something like 435VDC, and the 82K plate at 140VDC, so obviously way off. This is the channel A Phase Inverter.
I changed the 91K out, and 82K no change, and there's still the same wacky voltages on the plates. I've tried different tubes here.
Channel B PI voltages match the schematic A-OK
So what else could be causing the lack of voltage drop, and waaaay too much?
The channel B PI has proper 330V art the plates, and 76V at the Cathode . Channel A's cathode is 125V
Also, all voltage on the 6l6s are spot on, screens have good voltage, grids, etc
If it weren't for these wacky PI voltages, i would suspect something else, but this seems like a good place to start now.
Maybe the .1 couplers?
https://schematicheaven.net/boogieamps/boogie_5050.pdf
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