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Re: BF Princeton Reverb. Add 100 Ohm Heater/Lamp Resistors?

9/3/2003 9:23 PM
Rick Erickson
Re: BF Princeton Reverb. Add 100 Ohm Heater/Lamp Resistors?
Some b.f. Fender p.t.'s had an internally grounded center tap. If this is the case you really can't disconnect it without dissecting your transformer. I would disconnect the 100 ohm resistors and measure the resistance to (chassis) ground from the heater leads. If there is very low resistance to ground you have a center taped heater. If it reads open then your power transformer has likely been replaced in your "bone-stock" amp. The modern replacement transformers don't have a heater center tap, they use the 100 ohm balancing resistors.  
The Red-Yellow wire is c.t. for the high voltage winding. The orange wire is an internal shield and has no direct connection to the transformer windings.