I'm just now doing another set of coils that I've had for way too long. For the past several sets of coils I've done, I simply baked them in my oven on a sheet of aluminum foil at 250 degrees. Then I take them out and carefully scrape out the tar with a cheapie screwdriver. However, you can imagine that this smells pretty bad and insures that the oven needs frequent cleaning, to say the least. Thank goodness I'm single!
My question is, how do others do it? Is there a better way to remove tar that I simply haven't thought of?
Geez man, what are you trying to do? Remove all the tar and for what purpose? Here's my "I've done a few" (about 20) method: First I try to get the coil to work. Clean points ect. If it works I remove the brads and the sliding door and usually can get the narrow condenser side of the case to come off by passing a putty knife between the case side and the tar. This gives a clear shot at screw drivering out the tar & condenser. The glass insulator stays. Solder in the new cap, replace the wood side then add some wood spacers so not much tar is needed. Next I heat the tar I removed in a tin can. The can has a spout bent into one side and I use a vice grip pliers for a handle. A propane torch supplies the heat. This is done outside. No problems that way. Used to use the side burner on the BBQ but the torch is faster. Pour in the tar and close the box. I don't sand the box. I found a single edge razor blade does a nice job of cleaning the wood. Stain, paint the top flat black, make it purdy and into the car or when I complete a set of 4 it's on to e-bay. I horse with any that don't work later. Breathing patients first.
Here's a brass rolled top coil I completed. it was an unholy mess when I started.
I do them like Charlie. I would add that before I solder in the new condensor I twist the wires in place, install points and test the coil. Then I add tar and finish it up. Nothing worse that soldering in a new condensor, re-potting with tar only to find the secondary is flashing internally and not working properly.
Left that out Gary but you're correct. I do re-test before closing. I use a train transformer's aux AC terminals for power.
I went to Harbor freight and got a heat gun to melt some tar out. Kinda slow, but it worked. A better quality heat gun would certainly have been more effective at getting the stuff out. I've heard some guys freeze the coils and then just chip it out. Haven't tried that though.
Suggestion, before you melt the tar out put a piece of tape down each side over the slot. Keeps the tar out of the slot.
You will certainly remain single if you continue to melt tar in your kitchen. Go the opposite way. Put the coils in your freezer for a day. The tar will become very brittle and will easily chip out with a sharp screwdriver and small hammer. Much less messy and will not make your house smell like LaBrea tar pits. Try it,
Yes I don't know how a steak in your oven after roasting coils in it would be anything other then "Bituminous"!
It could be anthracite. Either way, would smell like tar.
I have done the melting in the oven a couple of times, kept the fan on and the door open, was not as bad as you might think. Of course I have a gas oven and my big worry was for the door on the oven to blow open, never did! Could be the flames from the burner burnt the smell right up.
While certainly not a professional, I've done probably 100 or so. I do them just like Charlie said. Pry off the wood on the condenser side.. The condenser is easily removable then. With the new flat style capacitors Fun Projects and Lang's sells, there is no need to remove much more tar. Maybe some up above the condenser where the terminals are located if necessary. Every now and then I'll get a newer style coil that has either the long skinny round capacitors or one of the small capacitors. Those require a little digging, but not enough I would resort to trying to melt it out.
Buy and old used toaster oven and do it outside on the picanic table . Or, use a big old straight electric soldering iron to melt, then pour out, only the tar you need to from around the areas you need to. Jim Patrick
My friend refills the coils with silicone, doesn't mess with the tar, Don.
Not to argue with success, but to pass along what others have said, for those who are interested in potting coils, here's a good read:
As I have mentioned here before, silicone contains acids that will, in the long run, attack and destroy the wire and solder connections.
I have worked on many coils previously filled with silicone and what a mess to repair.
For this reason I would prefer to work on coils no one has previously tried to "repair".
Ron the Coilman
Here's how I fix my coils...
1. Box up suspect bad coils
2. Mail them to Brent Mize
3. Brent checks them, replaces those that are bad
and sends good one's to me.
4. I pay Brent.
Lately an alternative:
1. Take a leisurely drive to Joe Bell's place with
said suspect coil(s).
2. Check them on his HCCT.
3. Swap out any bad one's with good one's that I
believe he gets from Brent.
4. Pay Joe
5. Enjoy a leisurely drive home.
All is good.
LOL Tim that's what I'm talking about. Leave all the black magic stuff to the witch doctors. No need for me to fool with that.