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IBM Wire Relays

A YouTube introduction
https://www.youtube.com/watch?v=l8DOfmVad9U

A collection of e-mails

- from Robert Garner to Brenda Make
dated Wed 3/6/2024

Brenda Make, Thanks for your in-depth description, characterization, and recommendations for refurbishing our tired wire relays. It all sounds reasonable to me! :) To share your insights, I’ve cc’d a few other 1401 team members. Happy New Year and Take Care, — Robert

On Dec 30, 2022, at 12:37 PM, Brenda Make < brendieellen @ brenda - make . com > wrote:

Hi, Wire Relay-Overall The wire-relays are fairly fast actuating relays, apparently developed made for 1940s and for logic use. The movable contact in them is silver or gold plated wire. The wire end is bent for grasping and alignment. Two wires are used for each relay contact, double non-wipe contacts. There are non-latching as well as latching varieties. The latching-type relays have a cylindrical coil on the top their metal bracket. A rounded guide pin is moulded into the bottom of each relay. This pin is actually hollow, likely plated-brass, which work-hardens. The pin can be bent or broken on relay insertion or extraction. Wire Relay Coils The non-latching ones often have 2 coils, one for Pick (up) and one for Hold. The outer coils are Pick; the center for Hold. Generally, the leads for the coils are marked for polarity--not for winding pairs. The wires suggest the coil resistance, which I have seen either ~600 Ohms, or ~1,500 Ohms. Oddly, many of the relays have the same Pick and Hold coil DC resistance. The latching ones I have see use the Hold contacts for the latching coil. Relay Wire Contacts All the contact wires I have seen are silvered wires ones. While the silver-plating tarnish is conductive, some wires have tarnish and corrosion that can felt with a fingernail. Some wires have varying amounts of tarnish removed by the moulded-on contacts. Some wires have shiny wear marks perpendicular to the length wire, suggesting that the silver may be worn through. Moulded-in Contacts The contacts that are moulded into the relay base appear to be silver-plated also--including the socket contacts. Cleaning the contacts non-abrasively would likely require: disassembling the relay, and either checking with a feeler gauge, or adjusting a over-travel adjustment screw threaded into the bottom of the relay, upon assembly, not to mention desoldering/resoldering the coils. Two tiny springs are in each relay, which are about 3/32" in diameter. Preliminary Restoration Notes: Generally, I am testing relays with more-often working normally-closed contacts, but failing normally-open contacts. This is consistent with tarnish caused by the sulfur in our air, as well as likely corrosion caused by the same moisture that caused the blade-contacts, screws, and the back chrome trim to rust in the German 729 tape drive. My theory is also that when we destructively examine a wire-relay, we will see steel corrosion where the silver has worn on the contacts, as well. Current Restoration Effort Fortunately, we have a decent, but exhaustible supply of replacement wires. (Each relay takes at least 8 wires.). I feel that the conduction of the wires warrants replacement. The replacement wires are identifiable by fine tooling marks on their side. Otherwise, they appear to be a direct replacement. A few relays wires have been replaced, already. These were quite lightly cleaned with #2000 paper. "The weight of a cigarette paper." --David, from Prometheus We have one IBM relay burnishing tool that I feel fine enough (#1000-#2000) to clean the moulded-in contacts. This tool is so fine you can barely feel the grit on it, if it is grit; it may also be sandblasted hard-plated steel. Also, this tool remains flat(er) as not to favor the outside contacts. For that reason, gentle and level pressure is best. IBM's stated tolerance on the non-adjustable contact gap is .001" or the thinness of a cellophane wrapper. Even with the IBM burnisher: very light pressure, very square to the contacts, try to get the center ones. Manta: please get it done within 5 short movements. (I feel that we also have an assortment of files and coarse sandpaper that should never be brought anywhere a relay.) [A safer process to clean the contacts: to suspend the relay, immersing the contacts in an ultrasonic cleaner. This would negate the disassembly/reassembly issues involving the coils. A small amount of Kool-Mist type mist/flood coolant solution could be added to the distilled water and cleaning solution to prevent rusting of the steel. The distilled water over mineral-rich water would help reduce rust, slightly, as reported by flood-coolant machinists.] I have placed the old contacts in a bag, so they may be batch cleaned, at some point. If we obtain chemical silver cleaner, it's probably best not have the container open longer than we have to. It's amazing that it can cause goiters! I have been cleaning the the tarnish from the relay (blade) pins using folded #2000 paper. The aim isn't to make the blade spotless, getting at least 50% of the surface shiny. Also, cleaning the Common contacts are not easy. Fortunately, that has not been a prevalent problem. I used Deoxit on a swab, with very firm pressure, with the aim that the fluff on the swab will clean the inside the contact wire hole--and not just the surface. What didn't work well: Cleaning the moulded in contacts with unsupported sandpaper. Perhaps reusing the wires we have. Take Care, Brenda (Adding....) Before placing the wires in the relay, the relay is cleaned with canned-air to remove particles, and then contacts are sprayed with Isopropyl alcohol. (I would worry that the working contacts, if sprayed with contact cleaner that contains oil, that the oil would carbonize, while Picking (making) and breaking. Using a swab, Dexit, this time with oil is wiped on the relay socket contacts (only), so lessen the relay insertion/extraction force. Take Care, Brenda

From: Brenda Make
Subject: Re: Link for plating kits & supplies (for our bad relays?)
Date: December 24, 2022 at 7:02:20 PM PST

Hi, The Relay-Extender seems to be done. Appears to have no shorts. All contacts connect. I cleaned it with isopropanol, but it should have a bit of deoxit, and a blast of air to make to make sure there are no solder balls. To make it less sketchy to use, tapered pins could be used--instead of probing the contact edges. I added a little heat-shrink here for peace of mind. They the nature of the thing means that stuff is exposed. Wires could be added to a wide connector, I don't have anything to use. It's silicone wire, so it's way bendy. Take are, Brenda