contact wire for Allen Analog TC-3

[storckm]

Hello Again:
I will soon begin the next stage of restoring my TC-3: fixing dead keys. First off, I'll need to replace the contact wire for a few keys on the great. Do any of you happen to know a source of contact wire? And is getting access to the contacts on the great very difficult?

[toodles]

Try Klann organ supply. They provide pipe organ parts, and make switches, etc., that incorporate wire like this. They are friendly to hobbyists. Call, don't email, to get a faster response. Tell them what you are doing.

[jbird604]

Good plan. I have bought some replacement wires from Allen, but of course they don't sell to non-Allen techs. It is quite a chore, so think long and hard before you make your first move!

[storckm]

Before I got these responses, I e-mailed Allen, and they told me to contact their local dealers. The local dealer said they could probably order the wire for me, but had a minimum order of $20 from Allen. They haven't gotten back to me with the cost of the wire yet, but assuming it isn't that expensive, are there other parts that I will be likely to need, and that I can only get from Allen?

[jbird604]

Probably not. These organs are built like a tank, so other than contact wires there aren't many things that commonly fail. You will need a number of 5 and 10 mfd caps to repair dead oscillators (which usually go silent when the keying capacitors dry out and lose value), but these are available cheaply from any number of sources besides Allen.

When ordering from Allen, the wires come in packs of 20, so you have to order 20 at a time even if you only need a few. But it will be a good thing to have some on hand for future failures. I have no idea how much your dealer will need to charge you for a package of 20 wires, but hopefully it won't be a lot.

[storckm]

One more question about the contact wire: Originally, Allen recommended Duco cement to hold the new wires in place. Is this the best option, or are there better, more durable adhesives available?

[jbird604]

That sounds good to me. I don't remember having to use any cement on them, just poking them up through the wiring block and soldering in place. If Allen recommends Duco, that is probably the best thing to use.

[storckm]

Well, I'm thinking of giving up on the Allen representative. I see on e-bay I can get a roll of 26 gauge half hard sterling silver wire for about ten bucks. Will that work? The diameter seems about right, but I'm not sure about the temper. For two dollars more I can get full hard. Would that be preferable? Or do I not want solid silver wire at all? I see gold filled (12kt) half hard and full hard as well, for about $12.

[indianajo]

silver isn't very stiff. If the contact wire is a wire stuck straight up or out through a hole, I would be tempted to coat a piece of music wire (stiff steel) with silver solder on the end. Silver solder is what they use on copper plumbing these days, available at most home repair centers and hardware stores. Use a propane torch to melt the stuff. I've put silver on tungsten steel contacts in a relay I am using for music. (The relay was originally for 3 horsepower 600 volt AC service).
Silver is not an ideal contact for low energy signals, as it does oxidize. Palladium, Rhodium, and gold are better. One source of rhodium I know of is the contacts in the $2 telephone relays I buy from electronic surplus. another is contacts out of switches on old Hammonds. Only the very end is plated, but that is all you need. One hammond scrapper is tonewheelgeneral.com of KC, MO. Negotiating the proper length of contact wire is up to you and him, but Rick is known for answering the phone.
Melting a "gold filled" silver wire onto a hard metal contact would not necessarily put the gold on the surface.
Duco cement is a rubber cement suitable for gluing metal to something else. I've used it over the years. It is for sale at Family Dollar here. You can buy quarts of somethnig similar as "tire bead seal" at the auto supply.

[storckm]

According to the Kimber-Allen catalog, they sell gold filled phosphor bronze wire for low current electronic organ contacts. I've found 26 gauge gold filled wire listed as hard temper, but I'm not sure what the core is. I'll look into the Hammond contacts, though: Thanks for that.

[indianajo]

Phosphor bronze is an ideal contact base material. It is both very stiff, low corrosive, and wets solder well to attach wires on it. With precious metal over the mating end, that is even better.