Rusty PT on '66 Champ

[AxeAmpTN]

Hey y'all!

A customer has come to me with another "attic" find.  This time, a 1966 Champ.  It is surprisingly clean (other than sticky-feeling tolex).  Now there are several things wrong inside the chassis that I know will need to be addressed.  The big question for me is the power transformer: 

There is visible rust on the tranny, which I know can be an indication of problems inside the windings, etc.  I haven't yet disconnected everything to test the voltages on the secondary, so I don't know how it will perform just yet.  But for those of you with lots of experience on rusty transformers:  do you have any advice going forward as I work on reviving this for my customer?

[kagliostro]

Perform a test on the Transformer

if all is OK

Don't remove rust with abrasive paper or steel brush, clear (as possible) the rust with a rough cloth, then paint the transformer newly with a spray color

--

in a far past laminations were exposed to weather as to have it rusty, the rusty acted as an insulation for the laminations, so, rust is not a big problem for lamination

Franco

[tubenit]

Don't remove rust with abrasive paper or steel brush, clear (as possible) the rust with a rough cloth, then paint the transformer newly with a spray color

+1

[PRR]

So if the PT were bad, you'd throw the amp away?

Seems to me a Champ PT is readily available and not very expensive.

But that rust does not worry me. Anyway PTs can go bad without visible rust.

I don't even see the need to "disconnected everything" to test it. Start with a lamp-limiter, see if you get almost-right voltages inside. Smoke test a while, bypass lamp, let it cook for some hours. I say 9/10 chance it has some decades left. So get the blackest oil-base wood stain, rub over the rust, it will vanish.

[AxeAmpTN]

So if the PT were bad, you'd throw the amp away?

Seems to me a Champ PT is readily available and not very expensive.

But that rust does not worry me. Anyway PTs can go bad without visible rust.

I don't even see the need to "disconnected everything" to test it. Start with a lamp-limiter, see if you get almost-right voltages inside. Smoke test a while, bypass lamp, let it cook for some hours. I say 9/10 chance it has some decades left. So get the blackest oil-base wood stain, rub over the rust, it will vanish.

No, nothing's getting thrown away.  Just looking for the best way to use what is here.  In a worst case scenario, a transformer can be replaced.

I'm disconnecting everything because I know for sure the caps are 50+ years old and the previous owner bypassed the on/off switched and hotwired the 2-prong AC cord to the transformer.  But as if that's not bad enough, the end of the cord is cracked or melted.  Like I said, there is a lot that is wrong inside the chassis...I have a game plan for that, but trannys are not a strong part in my knowledge/experience base.

And thank you everyone for your advice on wiping/painting!

[sluckey]

I'm disconnecting everything

I would just pull the tubes.