Rebuild transformers ??

[ward]

I have these old transfos I'm going to use for a guitar amp.
They're very rusty.

---PT----

---OT---

I thought about giving them a coat of varnish or paint to stop 'em from further oxidising, and came across this site:

http://home.att.net/~chimeraone/vintagetransrebuild.html

What do you think of this ?
Worth the trouble ?
If it's not adding life or quality to the transformers I certainly wouldn't bother.

Thanks for reading

 

[rodabod]

I think I would just leave them, or spray some WD40 on them.

 

[adamasd]

WD40 is alcohol based and evaporates off, it does not leave a protective coating. It is a temporary lubricant not ment to protect metal from rusting.

I would just take some really sticky tape and use that to pull off any loose rust and then give it a coat of rust-o-lum. Put some painters tape on the bobbins to keep the paint out of the winddings. Not sure what the electrical properties of rust-o-leum is but it is easy enough to keep it off the bobbin completely so might as well.

adam

 

[SSLtech]

Several well respected people have quietly suggested that rust makes certain transformers sound better... and no, this isn't a joke.

Keith

 

[CJ]

Yeah, output at least.
i hear SRV used to take a hammer to his output.
i figure this would either de-mag it, (if you drop a magnet, the mechanical shock will dis-align the domains) or to inflict core damage due to shorted lams which would saturate earlier.

here i9s a blurb from the mercury site.
it talks about core steel being "pre-treated" with a fine coat of rust, not rust after the xfmr has aged.

I don't know about the paper vs bobbin thing.
I believe the paper core tube lets you get the wire closer to the core, which is desirable for good linkage.

 

[PRR]

> WD40 is alcohol based

No, WD40 is kerosine. Specially selected kerosine, not home fuel oil or Diesel oil, but that's all it is.

As such, it leaves a "film" for "a while". Weeks or months depending on exposure.

I agree that this is not an appropriate "fix" for transformers.

> They're very rusty.

So? Rust does NO harm to transformers. Oh, if you soaked one in the ocean until 10% of the iron was gone, you'd change the inductance... except long before the loss of iron mattered the copper windings would be corroded through.

> stop 'em from further oxidising

If you don't want to see rust, keep your gear out of damp basements!!! That's the main source of rust. If you keep the gear in a nice room and use it often, it won't rust much.

> came across this site

Entertaining. But "When you shut down a hot transformer condensation takes place" is just wrong. And his process to "purge out any chemicals or moisture" is probably just roasting the shellac. If you just leave tube gear on for a day, there will not be ANY moisture inside (even on a damp day). What other "chemicals" would get in there? And how is a simple heat and dip going to get new shellac into ALL the internal spaces? Doesn't happen.

If the looks bother you, brush off the loose rust with something softer than iron. You do NOT want to damage the iron in any way. A power-sander or wire-brush will smear the edges of the laminations, give inter-lam shorts, and large losses. Gently take off what wants to come off. Then apply thinned paint to seal the surface and make it look pretty.

I would not "fix" either of the trannies in your picture for a guitar amp. Most of my older gear has more rust than that, and works fine.

 

[ward]

thanks for the advice !!
:thumb:

 

[Gus]

I am fairly sure I have seen transformers with the lams welded together down the sides. Maybe it does not matter as much when it is at the edges?

 

[The Kid]

I am fairly sure I have seen transformers with the lams welded together down the sides. Maybe it does not matter as much when it is at the edges?

Yes, you have; I used to TIG weld 1000's of trafos (they went in fryers for McD's). They'd get 4 seem welds, 2 on each side. And I can tell you first hand, what PRR said about sanding/grinding is right on. I tried to fix a couple ****** up welds that way, but they never made it past test dept. ! (Although they got a good laugh over the effort!) :grin: Yeah, it really ***** 'em up. You might try a bronze wire brush, but be gentle!

Sandblasting might work, assuming you used a really soft media, such as walnut shells, but never tried it personally, so. . . (I was thinking electrolysis, but then you'd have to worry about magnetizing the core, so that's out!)

 

[Sleeper]

Navel Jelly :?:

 

[gar381]

This Dynaco ST70 built in 1968 Has the orginal tubes
and blows away my McIntosh MC2105. This Rusty
Piece-O-S**t Is the best sounding Amp I own.

IS THIS ENOUGH RUST FOR YOU???

(gotta love tubes and rust!!)

GARY

 

[NewYorkDave]

That looks like my McIntosh MC60... Which was in good shape till it spent about four years in a non climate-controlled storage unit :sad:. Now I've moved it to climate-controlled storage and I'm contemplating ways to remove the rust from the chassis without ruining what's left of the plating or the printed legends.

Come to think of it, I have an ST70, too... and that's been sitting in a damp basement for years. I cringe to think of what it must look like now.

 

[kiira]

Serious rust can be removed with vinegar. I don't know if this would be a good idea with a transformer, mabe if you just submerged one edge at a tine. It works like magic on rusty iron and steel. Even tools come out sharp, like really rusty old files. Soak the rusty things in white vinegar for about a day. I learned this from a old grumpy machinist guy who was an apprentice in England working for the railroad. He told me that to graduate to being a journeyman you had to be able to file a perfect square in a thick piece of steel and a square piece to pass through it with no light showing.

Kiira

 

[emrr]

That's the kind of tip I like Kiira; nice and practical. Let's test it on one that doesn't matter.

 

[mikka]

I just sprayed an old fooker black (tranny, not journeyman). That way it LOOKS taken care of.