Blackface Princeton reverb smoke

[SelmaSedlak]

Hello,

I'm having some troubles with my new AA1164 Princeton Reverb build.
https://www.tubeampdoctor.com/media/pdf/80/ee/16/full_documentation_bf-14-rev_3.pdf

I made some initial testing without the reverb tank. The voltages and sound seemed fined.
But when i connected the reverb tank, smoke occurred after a couple of seconds from the insulation of the wire connecting pins 1 and 6 (plates) of the V2 reverb driver. The red arrow marks the spot on the attached photo.
When I removed the V2 tube, amp was working again.
Sadly after some hours of searching for wiring errors, shorts etc., I tried to plug the V2 back in and this time the fuse popped.
Now, while I'm waiting for a spare fuse and a new 12AT7, i would appreciate any insight on what might have gone wrong.

I was not able to find any wiring mistake.
I realise testing the amp without the reverb tank (as i initially did) is probably not a good idea, as it leaves the reverb driver/transformer without load. But from what I have searched on the internet, this should not be as great of a deal as doing it to the output transformer.

Could i have damaged the V2 tube or the reverb transformer by doing that?
When I tried the tube in a preamp section of another amp, it seemed to work alright.

The reverb transformer (125A20B 25k:8ohm) measures (disconnected from the circuit) 970ohm on the primary, 1.5ohm on the secondary winding. The primary resistance seems lower than what i have seen posted online. Could that be a sign of a problem?

I would be very grateful for any insight into the problem and will gladly provide any additional information.

Thanks!

[thetragichero]

trouble seeing v2 wiring. can you confirm which pin the blue reverb transformer is wired to? possibly confirm all of v2 pins and where they go?

[Latole]

Congrat, nice wring dress.

[SelmaSedlak]

trouble seeing v2 wiring. can you confirm which pin the blue reverb transformer is wired to? possibly confirm all of v2 pins and where they go?

it is quiete impossible to make a photo with the filaments wiring above the socket, but it goes like this:

- pin 1 connected to pin 6.blue transformer wire also connected to pin 6.
(before the fuse popped and the V2 removed, i had around 400 V on the pin 6, which seems right to me).
- pin 2 connected to pin 7. pin 7 connected under the board to the junction of 500pf cap and 1M resistor.
- pin 3 connected to pin 8. pin 8 connected to the 2K2 resistor a 25uf cap (these going to ground)

red transformer wire going to the near eyelet, then with a wire over the board to the X terminal of the can cap.
black and green wire going to the reverb connector.

I have checked for continuity between the pins that should be connected and for discontinuity between those that should not (and also to ground). everything checked out right so far.

I attach some overview photos. i have currently disconnected the transformer wires and the connection between pins 1 and 6.

Many thanks!
 

[SelmaSedlak]

Just to finish the story.
It took almost three weeks for the spare fuse and tube to arrive.
Even though i did not find any apparent error, i have redone the complete wiring around V2.
I switched the tube and fuse and the amp is up and running now.
So it seems to be a successful build after all!