transformer

[52 Bill]

Have you actually checked the amp? There are a lot of things that will give that same basic symptom of pilot light on, tubes don't light up.

[Prairie Dawg]

I think the Delta Blues has the same folded chassis setup as the Classic 30 and these amps are famous for doing exactly what you've identified. It sounds to me like you need to examine and validate the filament circuit all the way along, because that's the most common cause of losing filament current in these amps. The transformer probably didn't blow. You need to establish your filament voltage sources and t5hen start tracing outward. Your original transformer may have been OK all along.

[andyjazz]

I tore the transformer apart and found the thermistor to be toast. I fixed it with a soldered in 10amp buss fuse and got the amp running but there were popping and snorting sounds and a couple of power tubes were glowing way too hot. Upon further inspection I found that someone had put a 15amp fuse in where a 10amp should be. I missed this detail first time around (oops) guess this could allow enough current to somehow back feed and fry the transformer thermistor. Seems kinda weird tho.

So I went ahead and changed out the diodes in this section (There are two diode rectifier array sections on this amp) the section that is protected with this 10amp fuse. (A friend of mine said something anout a "flaky" diode so I figured wtf?) I also just went ahead (because I happened to have the parts on the shelf and the iron was hot) and changed out some big filter caps in this section and also several caps feeding the screen grids on the power tubes. I also changed out a cap on the preamp mixer tube circuit.

Also my brother-in-law the radio tech recommended I check all the ground connections. So I did a big shotgun soldering job. Tested the tubes (Two were shot) fired it up and no popping and snorting, no glowing tubes. I made a little test-point chart so I could check some V's and did some checking and everything seems to be OK. I'll play through it tomorrow for a little longer test but I think this thing is gonna work. Any suggestions, ideas, welcome.