Tweed Deluxe

[pnut5150]

I have a Fender 5E3 Tweed Deluxe here I’m trying to figure out. It’s mostly original except for the 3 filter caps and looks like maybe the output tranny has been changed possibly, the only numbers on OT is 108, the PT is original Triad 6452-E. My buddy got this and I added a 3 prong cord and he took the Jensen out to put it up because he wanted to gig the amp pretty hard so he put in an Emeince. He played it for awhile, now it has really weak volume, everything as far as caps and resistors check to spec..I’ve never had a OT work some but not all the way..is it possible it could be weak? Primary reads 278 and 283 to center tap, 380 across the plates. Nothing at all on the secondary side..any ideas? Seem like secondary may be shorted? I figured that would kill all sound if so😔

[Enzo]

Have we subbed different tubes into it?

Have we checked voltages at each stage? Are ALL the tube heaters glowing?

Two adjacent windings on a transformer could short together and your meter would never detect it. They don't usually short end to end.

Transformers do fail, but they are absolutely THE most reliable thing in an amplifier. The last thing on the failure list.

RG Keen has a dandy and simple transformer tester in his tech tips on his geofex web site.

The secondary is a small number of turns of heavy wire, it will have close to zero ohms resistance.

[Dave H]

Primary reads 278 and 283 to center tap, 380 across the plates.

That doesn't look right. I've just measured an OT and the sum of the two sides was within an ohm or two of the plate to plate resistance (as you would expect)

[pnut5150]

I have subbed in tubes no change, heaters are on however you can pull either tube and it doesn’t make a difference in the output volume, voltages all looked correct on tubes as well. A couple of the “dry” caps didn’t read well in circuit but read correct after I pulled them.

[Leo_Gnardo]

Primary reads 278 and 283 to center tap, 380 across the plates.

This does look ominous. Have you any known good OT's available? FWIW I typically keep at least 1 regular Deluxe OT around because it helps speed replacement once or twice a year when I run across a bad one - and this OT works well as a replacement in many other small amps. In any case, if you can clip in a known working OT, of any size, that will tell you right away if the volume pops back up to expected levels.

[pnut5150]

Hmmm

[pnut5150]

I don’t think I have any, I’ll check. I’m putting in some new filter caps, I know they are reading good, just wondering if internally they are breaking down they are pretty old looking.

[pnut5150]

I have a Reverb driver tranny, 022921..

[Enzo]

Weak filter caps might cause hum, they might cause distortion, but they won;t cause your output level to be super low.

[pnut5150]

It is breaking up really quick no clean headroom..but they didn’t help either.

[Leo_Gnardo]

I have a Reverb driver tranny, 022921..

Won't do, sorry. That's a single ended OT with perhaps a watt or so capability.

[pnut5150]

Right ohms, wrong wattage lol, I’m gonna order one right now.

[Mick Bailey]

I've had this before - two primary halves each measure a certain value, but measured end-to-end the reading is much lower. In every case the transformer had a short. The sign of a shorted transformer is very low output and excessive distortion. But that doesn't exclude any other fault that may produce the same symptoms. I always check and re-check that it truly is the transformer - the 'neon trick' is a good way if you don't have any other means of testing.

[pnut5150]

Ok thanks, guess I’ll build me a tester

[pnut5150]

Just a follow up, it was the output Transformer 😊