1952 Princeton - low output issue

[boroman]

I've been trying to track low output issue of an old Princeton, it's 5B2 circuit. Amp sounds great but it's way too quiet than it should be. I have later Champ and Gibson GA5 here, both are way (WAY) louder than Princeton and output of those is the same. there are some caps/ resistor changed in the power supply but it looks they are right. Since there's no voltage schematic anywhere, where I could look further? Amp sounds great and has great crunch when opened fully so preamp distortion is there... Also original tube chart says 6SC7 but is crossed and writted 6SL7. I checked those tubes and the seem similar so I dont think such big volume drop comes from here, even I I find 6SC7 somewhere (just a guess), but writing on the tube chart seems old, maybe factory mistake, so 6SL7 seems right for a 1952

1/ Tubes are okay (checked via tube tester)
2/ Original speaker & both transformers

[DrGonz78]

Well what are your voltages? What about the cathode resistor? What wattage are we getting? Are those old coupling caps holding up? All of those answers will get the great MEF minds stewing it over.

[boroman]

Well what are your voltages? What about the cathode resistor? What wattage are we getting? Are those old coupling caps holding up? All of those answers will get the great MEF minds stewing it over.

Caps are good. Electrolytics were replaced
16V across cathode resistor 0,5k = 91% dissipation.. looks right
344V on the 2 PS caps, 244 ov third one.

[boroman]

There are also 2 "extra wires" coming from OT primary - unconnected...
& there are also some more free pins on the sec. side (pic#2)
My first guess it may be impedance mismatchm but how to get to "which one is right"?

(I may think that OT is not original here... Maybe it has wrong ratio for that amp. Should be around 8K primary, 4ohm sec. for this....)
Original were different looking, TRIAD 6500 labeled.

[g1]

Did it work right with that OT before? Or is history unknown?

[boroman]

Did it work right with that OT before? Or is history unknown?

I just got it from my buddy that was saying "it sounds so quiet - it shouldn't" so I tried to solve that.

anyway

PROBLEM SOLVED.

I borrowed variac from my neighbour. Removed OT, tested and it has.. well... 28400:4ohm so WAY out of specs for the Princeton that should have around 8000:4
OT had 6 (unlabeled, yeah) secondary taps, I measured each ones in different configs, found one pair that is 9600:4 so hooked it up for a test and it's great now. May be still loosing just tiny bit of output, but sounds loud now! I Again, this is for sure, non-original OT.
Thank you all for the input!

[The Dude]

It's nice when the solution doesn't require buying a new transformer.

[mozz]

For voltages, a champ from the same (tweed) era may give a clue, a princeton was just a champ with a tone control back then.