Mesa Boogie Mark: Master Volume, Gain and power tube switch problems

[shooter]

In post #39 after we bypassed the lead section and reverb things appeared to be good.    leave the reverb section out, V4 pulled, reverb pot at 0.
see attached schematic:  use your signal generator and scope, set it for like 800hZ and adjust amplitude to about 80-100mV sin wave at pin 2 V1a.  leave EQ OFF, lead OFF, and measure and post the signal volts at points 1 - 4. Also note any changes in the signal, squashed, noisey, etc.

[JCK Bavaria]

Well, we did a proof of the voltages at the measure points, here is the result:

incoming signal: 80 mV
point 1: 3V
point 2: 100mV
point 3: 90 mV
point 4: 200 mV

Volume: 5
Treble: 7
Bass: 2
Mid: 3
Master 1,5

Sinus at adjusting knobs no changes, no distorted signal and no major bruises.

[shooter]

for the settings you gave, I think the voltages look acceptable.

Using the same setup, set master volume to 5 and re-measure point 4.
After that, turn lead switch on, master volume 5, lead volume 5, and again re-measure point 4.

what I'm "looking" for is a good clean drive signal to your PI.(phase invertor, or phase splitter)
Do you have extra power tubes ?

[JCK Bavaria]

well we did a measure of the points, but we do have a problem. After changing a resistor we had some failures. Now after switch to the lead channel the amp is very powerless. So we do have no comparison how the amp was before this incident.

The measures on point 4 are now:
clean 5 =  2,5 V
lead 5/5 = 80 mV 

[shooter]

after switch to the lead channel the amp is very powerless

I still believe the lead relay is NOT switching properly. 

changing a resistor

which resistor?