04-22-2011, 01:37 PM
codefox1 Wrote:I usually replace all the paper and electrolytic caps before I replace the power cord. That way I'm not tempted to power it up or lose track of what I am doing when several sets are being worked on.Hi,
That might be fine for those experienced in working with a set. But for new restorers replacing all the caps at once might invite trouble.
The bakelite block that the cord is attached to has capacitors inside that must be replaced. You can still do that job with the cord attached at this point. Next time though it may be easier on this block to replace the cord second.
Also for the new restorer, I would suggest that the filters be changed first, then a quick test. At that point you will usually hear some kind of reception. That shows all the circuits on the receiving ends are working. (Colis, tuning capacitor, etc.)
Once you hear it is receiving, power the det down, and begin to rebuild the bakelite blocks, and the free standing caps one, or two at a time. Then briefly test again.
The reason for doing it that way is that sometimes a wiring mistake is made, and rarely a bad part is installed. Changing one or 2 caps at a time makes it easier to see where you made a mistake if the radio sudenly doesn't work. Changing all at once (which some of us with more experience do) is harder to track down where the mistake was made.
Replacing 20 caps, then have a non working set, where do you start looking? It can be done but takes more time to locate the mistake.
Chuck's site has a good tutorial on how to rebuild the bakelite blocks, and data on what is inside them. Each person has their own way to do those. Some completely remove the block for rebuilding. It really isn't necessary in most cases. Removing the hold down bolt to the chassis, and flipping the block on it's side you can rebuild like that. Saves you from removing a lot of wires and components, then reinstalling.
I use a small embossing heat gun that has a 3/8" nozzle, to warm the casing just enough so the tar block comes out in one piece. (Along with the old caps). Don't get it so hot the tar starts to melt. Reinstall new caps, solder them onto the lugs and reinstall the block bolt. NO need to refill the block with tar, glue or anything.
Sorry for long post, let us know how you come along.
PS: That output trans can be saved. When you strip off wires like that, don't use the grab and pull method to strip. It can pull the wire right out of the transformer.
Carefully, cut the insulation off, without pulling on the wire. Now, add a wire to the bare and and solder it. Slip a piece of shrink tubing around your new lead, and shrink it over the solder joint.