Noisy Potted Iron

[W2VW]

I have a BC-610 F plate supply choke which was noisy. It's the later potted type. Anybody know if it can be cooked to reflow the potting and shut it up. How hot? What position? Should I drill a hole somewhere so it doesn't explode?

T.I.A.

[K1JJ]

Dave,

Being a creative guy, why not take the opposite technological approach, just like an alien?

Place it in a stout container and pump the air out, making a vacuum. No one can hear you scream in outer space.


Sorry, I have no advice for cooking it. Maybe axe Martha or Betty.

T

[Todd, KA1KAQ]

Gary WZ1M might be a good one to check with on this. He's had a lot of iron pass through his hands over the last decade and has probably seen this before.

He watches the forum from time to time, but his email is  xfrmrs@roadrunner.com

[WA1GFZ]

unsolder the filler cap so you don't build up pressure and then put it on the grill outside and melt the tar if you have a YL or XYL.
Single guys can use the oven in the kitchen

[k4kyv]

I don't think it's a  good idea to use a gas oven to bake a transformer, because the combustion process generates water, and it's not dry heat.  An electric oven should be used.

What's the worry about freaking out the XYL by heating a transformer in the kitchen oven?  When ours was electric, I used it all the time, and never left behind any unpleasant residue.  If you run it hot enough to smell smoke or burning tar, you have probably run it hot enough to damage the insulation in the transformer.  Just keep the temperature moderate and set the transformer in a pan so any tar that oozes out will not drip down to contaminate the oven.

[WBear2GCR]

Dave,

I have removed the tar from a small choke in an electric oven very recently... I seem to recall about 200 deg F, not more was quite sufficient.

As I said in another thread, I used an electric oven "rescued" from the throw-out pile at the local appliance store. It works fine and I have it in the garage (aka "the shop - no cars can fit in there anymore) near the breaker box. So no worries about drips and making food icky. Throw it out when it gets radically messed up, get another.

I'd put the connectors up, top of the can down. That's how it was put together. They had to solder the pins on the back of the feed throughs then fill the can with hot liquid goo, then let it cool and then put the can together and solder. Maybe some extra fill was done after that...

I think that the trick for you will be to let it cook in there for quite a few hours so that the innards can come up to temperature. For a choke that size, I'm guessing more than 4 hours, maybe as many as 8 hours. I'd bring it up slowly, you don't want to boil it out of the vent hole - I presume it is a soldered closed hole??

The vacuum trick would doubtless help some, if there is an air void in the choke somewhere, as making the bubble rise up out of the hot tar may or may not happen with ease or on its own.

You could prepare the choke with an assembly of  copper tube + fitting which is then soldered over the breather hole. Then once it is fully baked, you can pull it from the oven and place it on a suitable surface, connect it via the fitting to a vacuum source (not all that much is needed) and suck. That will pull the air out of the tar. Ideally you want to suck for a while and maybe have a good valve that you can close, keeping the vacuum.  The tar will be liquid for some many hours to come... so maybe the next day it will be ready to seal up... no voids likely.

                     _-_-bear

[WZ1M]

The potting material in these will not stay in a liquid form for more than a few minutes after the heat is removed. As suggested, try 200 degrees for several hours.
Regards,
Gary...WZ1M

[W2VW]

Thanks all. I had not considered the gas oven producing water.

I was going to replace the toaster oven anyway so it looks like I'll be using that.

[WA1GFZ]

Sounds like a project for the back yard.

[WBear2GCR]

Brain is on slow cook... I was thinking that to get all the tar in the larger pieces of iron up to liquid temperatures, the core will be raised to the same temp. You could unpot the iron from the can long before the inner core and the stuff near the core under the windings becomes liquid - or so I would expect. So, I was thinking that if a big core was raised to 200F it would not cool that fast... thus my comments. To get the potting fully liquid in Dave's case seems like a good idea since the hummy might be all the way inside the windings or in the core... having not experimented on big cores, I'm only conjecturing here.

                        _-_-bear

[AB3L]

A couple of years ago I repaired a potted choke. I was lucky enough to have access to high pressure steam lines here at work. I laid the choke, terminals upward, on a piece of sheet metal with a foil hood on top laying on an exposed (uninsulated) flange. Left it there for about a week to make sure it heated all of the way thru. It did put out a bit of odor thru this time which I wouldn't have wanted in the house.

[W2VW]

It did put out a bit of odor thru this time which I wouldn't have wanted in the house.

Thanks for the warning. I had an xfmr expsosion here a few years ago and it was not pleasant. I'll use a long extension cord off the back deck.