How old is too old?

[olddawg]

Given our recent discussions on power transformers and old radios, I'm wondering if anyone considers a "certain age" too old for a recycled build. Case and point. I just rediscovered the complete guts of a large old "furniture" radio. My brother gutted it years ago to make a bar out of it. It's early 1940 and has a huge power transformer with a lot of taps. (Since it had a 78 TT, an early AM/FM receiver and some really weird tubes) The output tube complement is a pair of 6V6s. Its an old Spartan. I remember it working in the 1960s, lol. The electonics, glass, and wooden knobs have been in a box in the garage for 30 years. I'm deciding whether to toss it all or keep at least the PT. Probably has a lot of heater current. I've repurposed and used a few weird chassis from the 50s. But something that is likely pre WWII seems a little iffy?

[Justin Thomas]

Personally, if it can be safely and easily wired to the mains and has at least a power amp using conventional tubes, I'd be willing to use it. There are enough test procedures to get a fairly good idea of whether it'll go or not (thanks, R.G.!) There is never a guarantee that anything will work upon fireup anyway, so what the hell? It's free. The chassis & trannies are the most reliable parts, and I don't think the technology changed that much. Smoke 'em if ya got 'em - hopefully not literally.

I've got a 194- Hammond tone cabinet chassis outside with a big old honking PT, 2 chokes, & two OTs - each driving 4x6V6s. I'll use it, as I think I've got the windings right...

Justin

[R.G.]

I would certainly keep the OTs and other stuff. OTs are under a lot less stress than PTs. I would use everything except the electro caps, but expect the PT to be hinky. It's probably designed for 110 or 112VAC on the primary, so be ready to adjust that, and get it running enough to figure out what voltages, etc are needed for replacement if the PT quits.

[bob p]

The electonics, glass, and wooden knobs have been in a box in the garage for 30 years. I'm deciding whether to toss it all ...

NO!!!

I guarantee those parts are something that an old radio guy would want. To throw them into the garbage could be like throwing the guts from a tweed bassman onto the campfire. Sacrilege!

Just because your guitar amp experience doesn't allow you to recognize some of the "weird" tubes doesn't mean that they aren't desirable. Chances are that you've got stuff that an old radio guy would love to have.

Just for reference: I rebuilt my Mom's old radio from the 1920s that she inherited from her great aunt. It's a giant double-door console unit that's about 5-feet tall and 3 feet wide. It only covers the AM band, but that's all that we need to tune into 670 to listen to the Cubs games. Original transformers, tubes, & speaker are 100 years old now.

[Enzo]

The part of old transformers I am concerned about is the insulated wires that come out from inside. If the insulation is all dried and cracked and crumbling, then it is dangerous. But the winding inside is not done with those wires, so the transformer with those crumbling wires may still be restoreable by replacing the outgoing wires.

[Rhodesplyr]

I work on Hammond Organs back to 1935, and one of the things that has become clear is that pre-WWII transformers and motor windings are failing at a much higher rate than post-WWII components.

I think that part of that is simply down to improvements in magnet wire coatings, both the materials used and how they were applied to the wire.

A friend of mine built a guitar amp using a 1939 power transformer removed from something. He tried playing a gig with it, and at one point, the venue folks were going around trying to figure out if something was on fire. Turned out to be his amp. Half the HV secondary had shorted. It smelled very bad.