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Posted: **Wed Jul 23, 2014 8:56 am**

4x4m38 asked this question so I am sharing it here in the spirit of information sharing this site is set up for.

I bought an ignition switch on Ebay with Douglas connectors. The wire insulation is surprisingly resilient and in decent shape. It looks like there was resin or some sort of epoxy material which enclosed the connections on the back of the switch. It was badly cracked and split in may places. I was able to take a pair of water pump pliers and apply pressure, splitting and cracking the insulation material further, which allowed me to get it all off.

The terminals and soldering on the wires is tight, with no corrosion, other than some light surface rust which should be able to be cleaned off with a wire brush or something. I know there is a pinout on one of the pages here for the headlight switch and hopefully the ignition switch as well.

My question is what would I go back with to reinsulate the terminal connections when I get to that point? Do I just make a round container a little larger than the switch and contacts and pour it full of epoxy?

My answer:

Brian,

The failed potting compound is common to very old switches. Sometimes cleaning up and re-potting works fine. Sometimes not. Risk is 50/50.

The compound you choose is up to you and your preference in materials and colors. Just google it:
https://www.google.com/webhp?source=sea ... g+compound

Most Douglas connector switches only have two or three wires.

2 Wire switch
Using a digital ohm meter test the switch for internal shorts.

With switch off check across the two leads for continuity. Should be none.

Then check each lead to the switch's metal housing for continuity. Should be none.

Now turn the switch on and repeat the tests above.

The two leads should now show continuity.

There should not be continuity between either lead and the switch housing.

3 Wire switch

With switch off check across the three wires in pairs (two at a time for continuity. Takes three separate readings. There should be no continuity between one lead and the other two but the other two should have continuity. (the two leads which share continuity are then labeled 12 (ignition) & 86 (accessory)

Check each lead for continuity to the switch's metal housing. Should be none.

With switch on all three wires should share continuity but should not show any continuity with the switch housing.

A word of caution, you should understand that a wiring diagram lays wires out so they make sense or logic as to their purpose and route. The wiring diagram does not show the physical arrangement of the wires or connector.

Posted: **Wed Jul 23, 2014 12:08 pm**

Here is the switch in question, part number 7760409.
The terminal for wire/connector 27 also has wire/connector 85 soldered to it.

The other two are 11 and 12 respectively.
85 is an accessory connection.

Posted: **Thu Jul 24, 2014 8:35 am**

Not to steal your thread, but Wes , I have an old 3 wire ignition switch like the picture you have posted with a wire broken off at the housing. Has anyone had sucess in taking that style apart and rewiring it? If so how do you open it up?

Posted: **Thu Jul 24, 2014 10:44 am**

Hi Bill,
Is the wire broken off outside of the epoxy/potting material or are you saying the solder tab has broken off at the rivet connector to the back of the switch itself?

Posted: **Thu Jul 24, 2014 10:57 am**

Bill that rt switch is not serviceable as is. It is a three terminal switch with 4 wires. #11, 12, 27, & 85 . That is either 11 or 12 that is broken of at the potting. The two together were 27 & 85. If you scrape out the potting you will see the three terminals solder lugs. Generally when they are in as bad a shape as those in my photo the interior of the switch and it's contacts are usually very worn and corroded.

The very older left switch with two wires the single connector wire is 11 and the double connector wire is 12. The double connector connected to #27 and #12.

Posted: **Thu Jul 24, 2014 11:17 am**

Thanks Wes. 4x4 the wire is broken just like the picture of Wes's ignition switch above.

Posted: **Fri Jul 25, 2014 4:57 pm**

You know, on a slow day, and for a lark, you might try and remove the potting to see if the wire is rusted/broken off at the terminal or if the terminal and everything else inside is fried as Wes said.

My potting material was dried and cracked, and I took a pair of water pump pliers and squeezed it in places cracking it further, allowing me to eventually remove it all.

The green is not a good sign, and is a an indication of copper corrosion.
There is a slim chance the wire was broken in parts over time, and corroded, and the potting material may have kept it somewhat localized. The corrosion would have travelled through the wire into the potting, eventually to the terminal.

If it was me, and nothing else to do today, I'd crack it open and have a look.

Just my two cents.
Brian

Posted: **Sun Nov 30, 2014 3:20 pm**

OK I had a slow day and was able to chip out all the old potting to get to the terminals that the wires were soldered on to. Have soldered on new wires. Now my questions is what was the potting material and what would be a suitable replacement in todays market?

Posted: **Sun Nov 30, 2014 4:10 pm**

Just google " Electrical equipment potting compounds " and pick your poison.

https://www.google.com/webhp?source=sea ... +compounds

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Igntiion switch testing

Igntiion switch testing