[DaleHCook]

For something like your rusty transformer housing my preferred approach is a Dremel abrasive buff, They are plastic sponge wheels bearing one of three grits of abrasive. They are much less drastic than wire wheels.

On using a dimmer, I would discourage you from feeding anything but a pure sine wave into a chassis under test. Dimmer outputs are too jagged and noisy. My custom bench AC power supply uses a Variac (if it isn't GR it isn't a Variac) and a true isolation transformer. See:

https://plymouthcolony.net/starcity/radi...tml#variac

and

https://plymouthcolony.net/starcity/radi...tml#wp-26a

[jrblasde]

Boy howdy, that’s some nice custom testing equipment! I really do need to invest in a variac. I also have a tube tester on my wish list. I currently have no way of testing tubes other than eliminating all other problems first.

I removed the bells from the transformer today, and the innards are looking more promising. I was able to clean up the two bells with the use of a couple of wire wheels. I’ve got a bigger, more powerful wire wheel on my bench top grinder, and then one which I can use on my drill. I then applied a layer of baking soda paste and let that sit for a couple of hours before rinsing and drying. Finally, I used some JB Weld Steel Stick putty to reconstruct the missing rivet holes where the transformer is riveted to the chassis. I’m letting that set for 24 hours, and then I’ll sand the putty flush to the metal and drill new holes. The bells should then be ready to repaint.

I will clean the exterior of the laminated metal tomorrow. I also need to reinsulate the wire leads. Tonight I plan to order the sleeves. The leads go into the windings of the transformer as one continuous wire; because the leads are not soldered onto terminals inside the bell, I am stuck with the original wires. But that is okay, I’ll get them cleaned up and install new sleeves.

By the way, I got a quote back from Edcor. I had reached out to them before I settled on repairing this unit. Their quoted price was even worse than Hammond’s!

[DaleHCook]

I currently have no way of testing tubes other than eliminating all other problems first.

Bear in mind that no tube tester can tell you if a tube is good - it can only tell you if it is likely or definitely bad.

[morzh]

Second that.
Had a superbad reaction of my McIntosh amp to ECC83 tubes that tested perfectly well. Redplated KT88s, blown up fuse...