Cardboard coated electrolytics

[Mars777]

Hi:

I've got a quick question.

I am working on a Motorola TS-4J chassis. I want to re-stuff the electrolytics.
I'd rather not have to un-crimp from the bottom like I do with aluminum type.

Do you guys know if the cardboard is being held by tar or wax? If I know for sure, and it is, I can then simply heat it up and pull the cardboard off.

TIA!
Tom

[bob91343]

It's not clear what sort of capacitor you are discussing. If they are chassis mounted with tabs,the cardboard is simply insulation and is usually glued on. If they are lead mounted tubular capacitors, there is more than one kind of construction. What brand and style are these units? Can you take a picture?

[Mars777]

Sorry bob91343, I should have been more specific.

They are just regular aluminum electrolytics with twist tabs on the bottom. Then they slid cardboard over them because touching the aluminum case could give you a shock as it is bus ground not chassis ground.

[bandersen]

There's usually a small glob of tar at the end holding the tube on.

[Phil Nelson]

I have seen cans like that held on by tar. Took a heat gun and patience, but the stuff eventually softened up enough to pull off the cardboard.

As a last resort, you can slit the cardboard on one side with a razor blade to ease removal. When reinstalling, glue the tube back together and put the seam on the least visible side.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[ctc17]

Re stuffing = exposure to PCB oil. Be careful all kinds of toxic goodies in there

[wa2ise]

Originally Posted by ctc17

Re stuffing = exposure to PCB oil.

PCBs were used in non-polar high voltage caps. Like values like 10uF at 1KV. Usually rectangular in shape. Electroytic caps don't have PCBs, but I don't know if there's anything else particularly nasty in them. Probably just mildly poisonous.

[Mars777]

Thanks to all!

"A small glob of tar at the end". I think that I will' try it from this angle. It is really stuck on there and I didn't want to heat up the cardboard forever if this wouldn't do anything. That is why I thought it was better to ask first.

It will be far easier to remove the cardboard, cut the aluminum around the circumference, re-stuff them, then finally glue it together. VS Un-crimping them from the bottom!

Sorry for asking about such a mundane question.

Tom

[kx250rider]

Ive taken those off, and IIRC, there's a blob of black crispy goop (tar, glue???) at the top, and another around the rim of the bottom. I was lucky enough to just work it by hand and break free, and without damage. If you have to, you can go to a packaging store and buy mailing tubes of that size, and spray them matte black. As said above, that cover is because the can is NOT at chassis ground!

Charles

[pallophotophone]

Hi,

Try freezing the condenser in a refrigerator's freezer compartment. It will make the tar even more brittle than it normally is and help the bond break free.

Pallophotophone

[bob91343]

I have seen them so loose they don't stay on, and so well fastened that there is no good way to remove them. Sometimes glue, sometimes tar, sometimes just a force fit. I guess there is no standard way.

Replacing it with a cardboard tube isn't what I'd do, as the original usually has markings. Try rocking it, wiggling it, and pay attention to where it moves and where it doesn't. You may have to cut away parts of it.

[Mars777]

Now that is something I didn't think of, "freezing it". I might give that one a try.

Thanks!

[Mars777]

Well, I got 2 of the three off so far. It WAS just a little bit of tar holding them on.

I was also pleasantly surprised that I didn't burn the cardboard doing it.

Thanks Again,
Tom