Princeton Reverb rebuild

[tonalvision]

Need help with a Princeton Reverb Rebuild. Started with a chopped up chassis from 1968
did repairs to the chassis itself and used eyelet board that had been built up by amp tech who did not finish job (long story). Bought new Trannies and pots, etc from David Allen Wired everything up using layout from schematic heaven. The amp powers up but does not pass a signal. I used the old light bulb voltage limiter trick and the bulb is lit without any tubes in. So it seems I have a power supply issue. Any suggestions? Thanks in advance for your help.

[txstrat]

I'd unsolder all secondary wires from the circuit and see if the light bulb still lights up. That way you can determine if it's the PT or the circuit. If the bulb does not lit you can resolder the secondary windings pair by pair to see when the bulb lits up again. From there you can check further.

[Amp Kat]

Agree with ^^^^and after that move from the power suplly back with all tubes out of course and start checking high voltages from the standby back then the other side of the choke and on down the line. Obviously the voltages will be somewhat higher with the tubes out so compromise for that until you find the short.. It sounds to me like it's under the hood so concentrate on getting those done 1st even if you have to undue the lead going to the nodes. Also check the heater wiring and make sure the 2 wires are isolated with all 4&5 pins going to 1 wire and the other wire going to all pin 9 sockets.

[tubeswell]

And how is your eyelet board mounted? (If it is screwed right onto the chassis, did you put a 2nd piece of (insulating) board material underneath etc?)

[tonalvision]

And how is your eyelet board mounted? (If it is screwed right onto the chassis, did you put a 2nd piece of (insulating) board material underneath etc?)

I used an old piece of formica. Any differences in procedure since this amp has no choke and no standby? Thanks to all

[tubeswell]

A 'stock' PR doesn't have a choke. But seeing as how a 5U4G is a directly-heated rectifier that starts almost instantly, a standby switch might be worth thinking about if your filter cap voltage rating is at any risk of being exceeded by the start-up voltage surge.

As for the formica board, as long as its electrical insulation properties are such that it won't encourage voltage leakage through the board, and (hint) as long as its mounted on standoffs or with some high-insulation backing to ensure the eyelets/turrets/other wires going through the board don't make electrical contact/shorts to the chassis that you don't want, it shouldn't present a problem

[Amp Kat]

A 'stock' PR doesn't have a choke.

this^^^^^ damn that negates the whole PR concept.

[tubeswell]

How so? (Did I say something wrong? ;-)

[tonalvision]

OK had another run at this thing. Pulled the secondaries and the light is still on but... I can't believe I have a bad PT. I hooked everything back up and plugged straight in and the amp passes a very faint signal. V5 seems cooler than V6 What next? The amp is not blowing the fuse. Have checked and rechecked wiring and connections. This is probably the most I have attempted yet as a build. Want to see it through. BTW I am using a GZ34 as specified by David Allen.
Spec sheet on PT says don't use 5U4G

[txstrat]

Is there a possibility of a short on the primary wires? Maybe a wire touching something it shouldn't.

[tonalvision]

Where should ohms read on primaries? Can I have a condition in there where it is shorted and won't blow the fuse? Thanks

[txstrat]

I was just poking around in the dark. Like a half conducting board or moisture or something...
I once had a bad power switch which blew the fuse with all secondary wires disconnected. But it blew the fuse anyway...
What if you just connect your PT to the mains with wires only (and the light bulb of course), no switch etc.
This could give you a better idea if the PT was bad.

[tonalvision]

Took it to a EE/amp tech, great guy. Traced out an unsoldered resistor (not mine) and a short in a twisted pair of wires (mine). all on the board. She sounds good now. Haven't mounted it in a cab to check reverb and trem, stay tuned. Thanks for all of the help everyone.