Mesa Boogie Nomad 45 PI

[Jazz P Bass]

Hello all.
I have a Mesa Boogie Nomad 45 on the bench. Came in with a blown output transformer & one dead 6BQ5.
I have a 14 volt ac output, max. Sounds kinda low for a 45 watt amp.
The strange part is the 12AX7 LTP phase inverter. I am getting a 23 volt signal on the top half & a 5 volt signal on the bottom half.
Bias is -12V. 68ma's current draw for each side.
All static voltages agree with schematic.
New output transformer ( 74ohms, both halves) & quad 6BQ5's from Mesa.
Now I understand PI imbalance & 100K, 80K plate load resistors, but this seems a bit much.
I have checked all resistors & caps.
This may be Mesa's way of getting it's sound. I don't know.
Anybody have any dealings with this beast?

[stokes]

Something is wrong with that PI,the signal from pin one should be close to the signal from pin six.I would check the signal voltage from each side of the PI with no power tubes,just to be sure the problem is with the PI and not a bad power tube on that side of the OT.

[Jazz P Bass]

OPT

Thanks for the info.
I swapped the primary leads on the output transformer. Blue, Brown. The issue is following the blue lead. Me thinks I got a bad transformer.

[Enzo]

GO over to RG's geofex site and check out his transformer tester. Something easy to make.

[Twist]

Did you measure the signal at pins 1 and 6 with the output tubes removed? Also disconnect the feedback resistor (if it has one) while checking.

[Jazz P Bass]

Mesa Nomad OPT

Alright. Checked the Nomad OPT. 74 ohms each side to red. Did a winding ratio test 100 volts Primary: 10 Volts secondary.
On a whim I put a Fender Princeton output transformer (150 ohm 100:6.5 ratio) in & the amp works perfect. I am seeing 8 volts on each power tube grid. 16.5 volts at the 8 ohm output. Now thats more like it.
To be sure I put the "new" replacement back in. Same mismatch on the phase inverter. 20 volts & 5 volts. The low mismatch follows the blue wire. I also found a low EL84 from the batch Mesa sent me.
Hello Mesa:{

[Jazz P Bass]

Got It Fixed

Sometimes it's the stupid stuff that gets you.
On the output board the ground wire & the feedback wire were inverted.
Thanks to all.
John