Russian Sovtek Mig 50 build issues

[quietcalmdeceased]

Hello, I have been tasked with trying to rehab my friend’s Sovtek Mig50(the Russian version with Vol I & II). It seems to have an issue where the pots aren’t affecting the signal. When I received it it was missing components such as resistors and a capacitor here and there. I went ahead and replaced all the pots and those missing components and no change had occurred. He wanted me to switch out all the tubes, so I went ahead and did that as well as the mylar capacitors, but the problem still persists. Does anybody have any insight as to what could cause this? Thanks in advance.

[The Dude]

Does this schematic match your amp? If not, please upload the correct one so that we are all on the same page. If NONE of the pots have an effect on signal, I'd be looking for a missing ground.

https://schematicheaven.net/newamps/sovtek_mig50.pdf

[quietcalmdeceased]

That is the one. Thank you for the suggestion I will re-check all the grounds. Sorry, if I put this under the wrong category. I just noticed that.

[The Dude]

...... more specifically, make sure the ground side of the pots is actually ground.

[Tom Phillips]

It would be a good idea to stop replacing parts for now unless you know of something obviously missing. Is there any sign of life at all such as the tubes getting warm / lighting up?

Let's do some testing assuming that you are aware of the necessary procedures to safely work on a live circuit.
A good approach would be to make some voltage measurements. Print out the schematic and write the voltages on the diagram then take a photo of the marked up schematic and post it. Measure the AC voltages at the power transformer windings and the DC voltages at the power supply filter nodes, the tube plate pins and the tube cathode pins.

[Chuck H]

This ^^^^^^^^^^^^^^^^^^^^^

Do not "fix" anything unless you know that it is absolutely related to a problem. Arbitrary replacement of parts only raises the possibility of new problems and can confuse diagnosis. I'm not questioning your work at all. But we all make errors I make errors. If any work you've done has errors there could now be new problems and related symptoms that can confuse definitive diagnosis.

[quietcalmdeceased]

The solder paths on the board were pretty bad. So, I ended up bypassing them direct to the next node or point. That seemed to fix the problem. Thank you all for your advice!