The PHILCO Phorum
38-116 speaker voice coil - Printable Version

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38-116 speaker voice coil - dixierat - 08-28-2009

My radio is the one with the badly damaged dial during shipment.Phorum members gave much needed advice on how to get it repaired. Bottom line is the dial was rebuilt using needed parts from a junker chassis and now operates smoothly.All paper and electrolytic caps were then restuffed and some 60% of the resistors were out of spec and replaced. All grommets on the RF subchassis were replaced. Fired her up slowly and current draw was 1.2 amps at 115V, no smoke or smells. But a dead set. Suspected voice coil or output transformer. Transformer was OK but one voice coil terminal was loose from speaker and coil wire broken. Other terminal was attached but coil wire was broken and partly missing.Missing about 3/8 in. of wire and the rest of the wire is varnished to the housing supporting the coil. I need to get the wire free from the varnish and and are considering 2 options. 1)dig the wire out with hobby knife or 2) apply paint remover to dissolve the varnish to release the wire. Also concerned with a tiny hole next to the terminal that a small wire may have exited.Would appreciate comments before I proceed.Thanks in advance from dixierat.

Re: 38-116 speaker voice coil - codefox1 - 08-28-2009

First of all, try connecting another p.m. speaker to the secondary of the output transformer and see if the set works. Consider any test speaker you use expendible.

The repair of the connection between the tiny wire from the voice coil to the lug on the frame is a delicate one. If you can get the glue or varnish off the 'spot' where the tiny wires come out of the voice coil on the cone, you can see if the voice coil still has continuity. I would try a tiny amount of acetone or nail polish remover on a small spotting brush, and do blot it very well. If this doesn't work, and you have a delicate hand and a sharp scalpel you could try to remove whatever is there to expose the metal. You can't burn it off, because remember, it's sitting on a piece of paper that is very very old.

Once you have determined that all is well, and the voice coil is not rubbing, you will prevail.

You will have to procure a small length of wire similar to what is on he other side. I have used bits and pieces of old phono cartridge shield wire, must have been decades ago in a similar rescue mission. Somebody on this forum probably has a roll of it and will step up and send you few inches of it, which will be a lifetime supply.

Anyway, once you have an exposed clean contact area, the most delicate of soldering jobs must be done to attach the wire to the spot on the cone. Tin the wire first, and make the connection quickly. Reinforce the immediate area around your join with the glue of your choice, and allow it to cure thouroughly. You then punch a small hole through the cone (away from the tiny wire from the voice coil, using a pin and gently enlarge it to accomidate the wire, feed the wire back to the terminal on the frame of the speaker, leave a little slack (look on the good side to estimate how much) so it can traverse the spectrum of the sound it should reproduce, and solder the other end. Finished!

There are as many ways to repair a cone as there are remedies for the common cold. Everything from toilet paper and elmer's glue to silicone putty, to rubber cement. What you want in the end is something that moves freely, is properly centered to avoid rubbing and buzzing, and works. Every tear, missing piece, and hole should be addressed to make this happen.

If you want inner beauty as well, and the set is otherwise OK, you can get the speaker re-coned. The experts who do this can take care of all this.

I have a similar set awaiting a dial plate, and the speaker was a basket case as well. It had all sorts of paper tape and glue all over it, and I reversed most of it. Looks like H**l, but plays pretty good.

Have fun. Now we'll hear from people who know much more about this stuff than I do, with even better suggestions

Re: 38-116 speaker voice coil - Jim Berg - 09-02-2009

I have a coil of the flexible lead wire that goes from the terminal to the voice coil. Email or PM me and with your address and I will send you a couple feet.

Re: 38-116 speaker voice coil - dixierat - 10-08-2009

I could not get the speaker repaired so I contacted Hank Brazeal and his conclusion was the speaker needed major surgery. Just got it back from Hank;it looks great,he does beautiful work. He tested it and says it sounds perfect. All I can get is static from the 38-116 so I have more work to do. Thanks guys for your help;it was much appreciated. But I had to admit defeat and call in the Marines{ Hank}.
Curt