Fender Champ 5f1 power transformer question.

The first shot stating 650v CT means 325 - 0 - 325 so not a problem. Similar voltages, just a different way of expressing it.

 

I believe the Classic Tone transformer is actually closer to "standard," for the 5F1.

Also, the current rating should be plenty as well and, again, I believe is standard:

1.2mA / 12AX7 triode x 2 = 2.4mA.
45mA / Anode Current 6V6
5mA / Screen Current 6V6

Total Current Needed = 52.4mA

Taken from JJ datasheets with typical operating point of 250v - I assume this to be a bit higher at champ voltages?

I could be missing something here so someone please chime in and correct my math as I'm still learning. Is there a current draw on the rectifier tube from the B+ winding? I assume not (not to hijack GratefulDean's thread but to clarify).

 

Since you are new to this, I suggest following Rob Robinette's diagrams on his 5F1 site. Mojotone just follows the 50's wiring diagrams. Rob's site has updated the wiring to more modern standards.

The HT Center Tap (red/yellow) can make for a quieter amp if it is connected directly to the negative side of the first filter capacitor. Mojotone does not ground it there.

I suggest elevating the Heater Center Tap to reduce hum. To do this the green/yellow CT is terminated at the cathode of the 6V6. (Pin8 of the 6V6 or the eyelet on the board.)

In other words, don't cut those leads short.

 

This is a great video to help you understand and maybe answer your own question.

 

Yes - there's internal resistance on the diodes, but it's minimal. The load is the plates, mostly power tube but the preamps dissipate a little.

Don't freak about 5-10 volts, it's not that critical. Old Fenders were made when wall voltage was lower. Now it's higher they're still working OK.

On two SF Champs I worked on B+ at first cap sectiin was 40 volts higher than nominal but still within tolerance according to schematic. The plate voltage was 15 volts high.