Power transformer getting hot at low volume...

[JDW3]

I installed a pair of el-34s in my Traynor Bassmaster and fired it up. It has a bias adjustmentpot, I set it by ear. There was no glowing of tubes, did not look hot.

The amp was on, out of the chassis and upside down. (Trannys facing down)

For most of the time, there was no signal going to the amp as I was busy, but a guitar was plugged in. I played occasionally very quietly. Amp volume on about 1.

I turned the amp over and noticed the power transformer was very hot.

Because of bias? Tubes were not overly hot.

[BLC]

Some power transformers get hot. never so hot that you can't put your hand on it and leave it for at least 15 to 30 seconds. Others do not get hot, just warm. Fenders usually get pretty hot. I have worked on Traynors, but dont recall about the power tranny. IF the transformer was not getting hot prior to you installing the new tubes, I suggest haveing the amp checked out. The power trans. is just changing voltages to run the amp. It dosent care if you are playing or not, or , loud or not....it just supplies the different volts. Knowing how traynors were built, i am surprized that it is getting hot.

[Blue Strat]

I suggest checking the bias other than by eye /ear which is totally ineffective if you want results. You can be at or near 200% (as opposed to 60 or 70% which is correct) idle dissipation without replating.

This whole "replating as an indicator of proper bias" thing is utter BS. Until you check the bias the right way, you're only guessing.

[Johnny Z]

Adjusting the bias by ear is like using it as a tone control. Your almost always going to under bias and run the tubes too hot. If you have a VOM you can do a prety good job adjusting the bias with the chasis open. I don't know the spec for your amp but would guess a starting point of about -35v for starters on pin 5.

[JDW3]

I have a Fluke multimeter. Is it possible to check/adjust bias voltage with this alone?

I was going to purchase a bias-probe.

[Blue Strat]

I have a Fluke multimeter. Is it possible to check/adjust bias voltage with this alone?

I was going to purchase a bias-probe.

A bias probe is easier and safer. To use the meter alone, Google "transformer shunt method"

[Johnny Z]

I have a Fluke multimeter. Is it possible to check/adjust bias voltage with this alone?

I was going to purchase a bias-probe.

Yes but I think Blue Strat is right. I should get one, it would save lots of time. I have pulled so many chassis for other reasons I guess I'm just used to doing that.