Blackface Princeton Reverb with 2.x vac on grids of v1?

[mort]

This is a complete rebuild I'm doing of a blackface reverb. The original parts are the chassis, reverb transformer, pots, jacks and preamp sockets. The cap can, PT, and OT have all been changed at some point but are not new. I installed new octal sockets, new bias board, new main board and all new wire, resistors, signal caps, cathode caps, etc. All power amp grounds attach to the cap can housings tags and preamp grounds get bussed and attached to the chassis near the inputs.

Trouble is I'm getting a lot of hum even with nothing plugged in. I've tried a new filter pack, different OT, and different tubes. Was just poking around in there and found ~2.3vac on the grids of V1. This is not normal is it? Thoughts on how to proceed?

Thanks
Jeff

[Jazz P Bass]

" The grids" as in plural?

The first grid should be 68K from ground.

The second grid, well, that is connected to the 'Volume' control.

That "2.3Vac" measurement sounds suspiciously like an un terminated lead on the meter. (ie: possible missing connection to ground)

[mort]

Shortly after making this thread I had a eureka moment. The PT the guy sent me doesn't have a CT for the heaters. Just installed a pair of 100 ohm resistors for the ground reference and voila, problem gone.

Now I'm either reading 0vac on each of the v1 grids but sometimes get a 1.3vac reading that pops up. Not sure what that means(maybe what is referenced in the post above^^).

[KevinOConnor]

Hi Guys

Make sure the ground you are using as a reference really is ground and that the circuit shares that reference.

Have fun