Ampeg V2 bias question

[Eggman]

I have an ampeg v2 ,selmer made, that has 1 power tube that holds at -65 while the other rises up to-75 and above. Most voltages are close with the main being at 545 instead of 590 on schematic. It’s only doing about 5-7 watts output. All basic stuff has been done without finding problem. Tubes, caps, and a few resistors in power supply and power amp section have been replaced. Still checking previous work and looking for something miswired. It’s not drawing excessive current as its been on full power after trying on light bulb. 1 correction I did find was 1 of the 2-10uf @100v bias filters was incorrectly installed.

[Eggman]

Following directions for a new post, I was unable.

[The Dude]

Is it this one?

http://www.kbapps.com/audio/schemati.../images/v2.gif

"1 power tube that holds at -65 while the other rises up to-75 and above" . Is that bias voltage or what measurement is it?

[Eggman]

It’s the bias on the 2 - 7027 power tubes. B+ is within tolerance as main is around 545 instead of 590 as shown on schematic. All voltages on preamp and phase inverter are good.

[Eggman]

Yes that is the schematic on the top cover with the reverb spring.

[g1]

Try disconnecting the coupling caps from the PI tube and see if the 7027 grid voltage changes.

[Eggman]

Will do

[Eggman]

I pulled up the caps and the B+ went up to 585 and the bias for 7027s remained stable. I replaced the bias supply diode and both tube sockets. Still only about 5 watts output.

[Eggman]

Is there a reliable way to test the output transformer?

[g1]

I pulled up the caps and the B+ went up to 585 and the bias for 7027s remained stable.

Something is not right there. If idle current for power tubes stayed the same, there is no reason lifting the PI coupling caps would have any effect on the B+.
Where & how are you measuring bias or idle current of power tubes?

[Eggman]

I am measuring the negative voltage for bias, not current.1 -7027 measures -65 and the other starts at-65 but drifts up to -74,5. When caps are out the voltage stays the same on both output tubes. The main voltage (545) rises up a little with caps disconnected. All voltages on tubes are fine. Also the preamp out drives another amp fine. Problem is in power amp. When all parts are connected the output is only about 5 watts so I am searching for something sending signal to ground.

[Helmholtz]

Confusion can be avoided by specifying the correct unit with a measurement value (V, mA etc.)

What are your power tube grid voltages with the coupling caps disconnected?
What are screen (pin 4) voltages?

Did you check the diodes D7/8/9/10?

[Eggman]

I will answer your questions on Sunday when I get back to the amp. Thanks

[Eggman]

Also the diodes checked out good on ohm meter and I also disconnected them but made no difference

[Eggman]

Saga of the V-2 that wouldn’t put out.. I took voltages on both power tubes and 12au7 with both coupling caps connected first and then disconnected. 7027 with blue wire to output trans pin 3=545, pin 4=577,pin 5= -73. 7027 with brown wire connected to output trans pin 3= -67, pin 4=483, pin 5= -67. With caps lifted = blue- pin 3=585, pin 4=583, pin 5= —68. Brown- pin 3=580, pin 4= 577, pin 5 = -68. Phase inverter 12au7 Connected = pin 2= -35, pin 7= .3, pin 1=192, pin 6= 192. Disconnected pin 2=0, pin 7=0, pin 1= 228, pin 6=230. Both PI and power tubes have been replaced with a few different tubes. Preamp out drives an external amp fine. I am using the amp from power amp in to check but all voltages listed were at normal AC. Maybe 5 watts coming out.