Johnson Loredo T25-R Power Transformer

[tdlunsfo]

These didn't seem to be paper, almost electrical tape like. I plan to solder the copper strap. I had little bit of room to get this accomplished.

[Helmholtz]

These didn't seem to be paper, almost electrical tape like.

Doesn't matter. I recommend Kapton (polyimide) tape because it (along with its adhesive) is high-temperature-resistant.

https://www.mouser.de/ProductDetail/...fex3QOS5TEYl24

[J M Fahey]

Interesting amplifier.

1) An excellent mix of a basic Tube amp with well designed and used SS parts, such as the Op Amp front end (short ago we were discussing a Fet or Op Amp gain boost in another amp) .
Basically 10X gain before even reaching first grid is good and makes tube quality, as far as microphonics/hiss/hum 10X less important (hey, 20dB down !!!).
And of course an Op Amp used at such low gain and signal level is absolutely transparent, the traditional "piece of wire with gain"
Refreshing after endless boring photocopies of photocopies of photocopies of Fender Tweed or Black panel 50/60 y.o. clones.

2) quite well made.
Not NASA technology or anything like that but proper commercial quality build.

I wouldn´t even straight point a finger at the PT considering that it may very well have overheated after some tube shorted or heavily redplated and original fuse was replaced by an indestructible one ... in which case the internal one did its job.

3) what is used in transformers is actually paper , just thicker and often preimpregnated with some kind of insulating varnish.
You can tape the wound, preferrably with paper tape (similar to what car painters use) but one with good adhesive, then brush some kind of wood/home varnish you have available. Once it dries you have basically same as original.
Plastic electrician´s tape is generally not recommended because it loses tackyness and drops off, or melts with as little as 100C ; cellulose , specially if impregnated, takes abuse much better.

As helmholtz said, solder copper foil properly.

5) IMPORTANT!!!! : schematic (which looks like drawn by some user, not Factory) looks good in general but "SS area" winding is 20VAC, NOT 40VAC.

Notice rectified +/- 27VDC supplies.

I find it unusual they used a half wave voltage doubler there but they saved 1 buck and anyway those voltages are filtered and regulated, so ....

[Enzo]

Speaking of electrical tape, one of my all time favorite products, 3M glass tape, #27

https://www.3m.com/3M/en_US/company-...4280636&rt=rud

[tdlunsfo]

Here is the schematic they sent me for future reference.

[J M Fahey]

The Factory schematic shows the proper 20VAC winding.