Bias 64 Super Reverb

I tried biasing but only got from -11 to -23 mA when turning the bias trim pot.

I first want to make sure I'm not doing something stupid - I am very careful doing this and respect amperes, believe me.

Shunt method:
Connect multi-meter (red) to the center tap of the output tranny. Connect black to pin 3 of one of the power tubes (Svet 6L6 Winged-C).

That's it but I can't get -30 to -35 on the meter (only from -11 to -23).

1. The center tap of the OT is red and is connected to the board. There is also a black wire from the OT connected to about the same spot with a short little jumper. Is that ok? The reason I'm asking is because the OT is not original - it is Schumacker 4ohm from 1968 - probably from a bassman.

2. Should the meter be set to V or mA? I am setting for 200 in order to get the reading.

If I am doing this right, it's possible that the resistor, the electrolytic, the diode or the trim pot is shot in the bias feed supply, right? If so, how can I know for sure which is fried? I guess the electrolytic should be replaced anyway as it is original 1964 (I've replaced all the caps under the pan, a few years ago).

Anyway, thanks for your help on the bias questions.

 

Thanks for all the answers everyone. William, you don't come across as condescending at all - you are absolutely right. I've been reading from lots of sources and still feel I may be doing something wrong. Ironing out the details is great advice, especially for something like this. I tried setting to 200 mA and got those low readings.

I have 3 sets of power tubes: Svets, Sovtek 5881 and Phillips 6L6WGB. Blue Strat mentioned that could be the issue. I haven't tried the Phillips yet. I guess I should.

The rectifier is a GE 5AR4 that is suspicious. I have a spare Ruby 5AR4 which I think is Chinese. I'll swap out the tubes and try again. If still no go, I may change the cap in the bias supply. If that doesn't do it - does anyone know a good tech in or around NYC?

Thanks again for the info!