How to Clean Plate Chokes and Output Transformers

[thdewitt]

Hello,

I am assembling my Stereomour and the Chokes and the Output Transformers are very dirty.  I want to paint them but was wondering the best way to clean off what looks like some kind or resin.  See pictures.

(https://dl.dropboxusercontent.com/u/38833957/2014-06-01%2020.06.49.jpg)

(https://dl.dropboxusercontent.com/u/38833957/2014-06-01%2020.07.03.jpg)

[Paul Birkeland]

That is the varnish that holds the iron together.  If you use a solvent to remove it, you will actually damage the transformer.

You can, however, sand the varnish off the channel frames, then mask and paint them.

[thdewitt]

Thank you.

[mcandmar]

If you can find a thick jelly like paint stripper apply it with a q-tip and they will be clean in minutes. Just be careful not to get any stripper inside them.

[thdewitt]

Has anyone tried to take the metal cover off completely, paint and then put back on.  I pulled one off the output transformer just to see how easy is was.  It was pretty simple.  just bend back the 4 tabs and  it pops off.  My worry now is will the paint chip off when you try to ben back the tabs.  Has anyone tried this??

Tom

[Paul Birkeland]

My worry would be that you could disturb the construction of the iron itself, especially the plate choke.  If any piece of iron you've done this to exhibits unusual vibrations when you run the amp, you'll need to throw it away and purchase replacements. 

[thdewitt]

Well I can vouch for what Caucasian Blackplate had to say

My worry would be that you could disturb the construction of the iron itself, especially the plate choke.  If any piece of iron you've done this to exhibits unusual vibrations when you run the amp, you'll need to throw it away and purchase replacements. 

I removed an Output Transformer bracket and a Choke Plate bracket before reading his post.  The brackets go back on, but they are not "glued to the iron" like they were with the varnish.  So now I am considering superglue in between the bracket and the iron.  Is that necessary.  Is there any reason why a bracket needs to be firmly adhered instead of just a bracket.  If so, what is the process for ordering a new transformer and choke before I go through all the work of putting this together.  My mistake.  Everyone else be warned!!!!

[Daikini]

I used fingernail Polish remover on q-tips to clean mine. Works fine if you're not in a hurry.

[Paul Joppa]

The iron components are vacuum-impregnated with varnish - drowned in a vat of the stuff then a vacuum is pulled (sucking out all the air inside the component) and as pressure is restored, the varnish is driven into even the tiniest spaces. This immobilizes the wires, preserves the relative position of the iron laminations, and protects them all from corrosion.

Basically all the individual parts (laminations, wire, bobbin, etc.) are glued together this way, kind of in the way that fiberglass or plywood is glued together. Ungluing any of those things makes it very hard to re-assemble  them correctly.

[Adrian]

A wire wheel on a drill or dremel also works well to remove the varnish from the bracket - doesn't take much pressure nor effort and you're done in no time.  Be careful to only brush the metal bracket.  Also, these trannys were not designed to be taken apart.  As posted above, this can damage the iron, which must be "tight" for proper operation.