Fender Hot Rod Deville Filament Winding Problem

[EstynEstyn]

I've got a Fender Hot Rod Deville. Here's the schematic.

http://www.blueguitar.org/new/schem/...od_deville.pdf

My problem is that when I turn it on, all is fine. Then over time, say an hour, the indicator fades to almost non existant and there's a light distortion. I guess this can only be the filament winding. Is there anyway to fix it, or is time for a new power transformer?

[52 Bill]

We need more information.

If the filament voltage actually dies out, the signal would also die out as the tubes need the filament voltage to operate. Do you lose signal or do you just get a little distortion?

I have seen the pilot lamp sockets on these amps act up and just stop working until they are cleaned up with some light abrasive.

Do you have a voltmeter available to actually measure the heater voltage?

[EstynEstyn]

I'm voltmeterless till Saturday unfortunately.

I just get a little distortion, the lamp is still lit but only just. That's why I figure its a transformer problem. I'll get some voltage readings done on Saturday and get back to you.

[Enzo]

Transformers can fail, but they are absolutely the last thing on the suspect list. And considering transformer failures, the heater winding is about the last thing on THAT list. And even if you do have a heater problem, it is not likely the transformer, it is FAR more likely a bad connection.

[Pedro Vecino]

Most likely it comes from a poor contact in the lampholder. Itīs quite common in this serie.
The way to fix is to use a small wire acting as a bridge between these two points:

[Amp Kat]

Agree with everyone above and transformers don't just fade, they are either all on or all off. Now I have seen heater sockets with cold solder joints do this which is basically the same thing that Pedro is posting just in a different place.