Hammond 291BEX heater winding grounding

[7xa12]

Thie Hammond 291bex power transformer has no center tap for heater windings. I am assuming it requires heater wires to be connected to ground through 100ohm resistors. Am I right?
Can i use the same grounding point with bias circuit cap for them? thanks

[52 Bill]

I am assuming it requires heater wires to be connected to ground through 100ohm resistors. Am I right?

I depends on what circuit you are building. The heaters could be wired with one side grounded like a Champ. That would not require the resistors.

Otherwise you are right, two 100 ohm resistors to ground will set the ground reference point without the center tap. Fender used the bias ground point at the power transformer mounting bolt for these resistors as their standard for years.

[7xa12]

thanks Bill. it is Fender deluxe AB763 I just finished. and now checking everything. so if the transformer has just a Ht center tap ( red -yellow wire) and there is no yellow- green wire ( heater center tap) the heaters wires must be grounded in Deluxe reverb? ( like in Hammond 291bex) Right?

[52 Bill]

...the heaters wires must be grounded in Deluxe reverb? Right?

Yes, you will need to add the resistors to reference the heaters to ground. You can use two 100 ohm 1/2 watt like the old Fenders had or use a 100 ohm wirewound pot as a hum balance control or two 47 ohm 1 watt resistors like some modern amps use.

[pdf64]

See the heater ground reference arrangement in http://www.webphix.com/schematic%20h..._nomstrvol.pdf