fender heater reference resistors

[MstrB]

a friends BF Tremolux cooked its PT after he did some of his own work on it. 1 of the things he did was lift the heater CT and add resistors to ground but instead of 100ohm he used 75ohm. I think this had a contributing factor on the tranies demise, what do you guys think?

[loudthud]

As long as the resistors didn't overheat and short out, they shouldn't cause a problem. 1/2 Watt resistors should be fine.

[J M Fahey]

lift the heater CT and add resistors to ground but instead of 100ohm he used 75ohm. I think this had a contributing factor on the tranies demise, what do you guys think?

No. Do the math yourself.
2 x 100 ohms would have "eaten" 0.2W ; 2x75 ohms should increase that to 0.28W.
Negligible load for that PT.

[jrfrond]

Not a chance in hell. I've seen as low as 50Ω in commercial gear.

If your friend had a heater hum issue and disconnect the CT to add balancing resistors in an attempt to remedy the situation, the heater winding may have already been shorted and on it's way out. I'm not saying this is the case, but if you already have a heater CT, there's generally no need to create on, unless there's a problem.

[Justin Thomas]

Hey MstrB,

I can say I did some work on my BF Bassman's bias board and shifted the pilot light holder's tabs over to ground by accident trying to shove the boards back in. I never saw it and that took out the heater CT on my PT... So I had to put in the resistors to replace it.

Check and make sure there's no loose or misadjusted parts that got shifted, as mine was missing the little insulating card by the pilot light.

Justin