Electrical connections

[BobFV1]

Hi all - need some advice.

I'm pretty anal when it comes to electrical work - generally solder and cover the connections with heat-shrink tubing.

On the recent relay job that Harry GPM shamed me into, I connected a four-pin electrical relay to four wires. The relay had little pins that a small spade connector slipped over, so I took the four wires and soldered spade connectors to them and slipped the spade connectors on to the pins on the relay.

I have sort of a bad feeling - like maybe since the relay is under my seat the spade connectors with vibrate off. What is the best thing for me to do? Solder directly to the relay? Heat shrnk over the spade connectors? Interested in your collected wisdom. TIA!

[R4R&R]

Bob,
When you put the connectors on the relay, are they tight? I have a similar setup for my accessory circuits and my connectors going to the relay are tight to put on, they do not vibrate loose. But....I have had them lose connection (I'm guessing from corrosion) over time. I hit them with a little WD-40 and slide them off and back on again and it works fine for many months.

[BobFV1]

John - yes hey are tight, but you are describing the type of thing I am conceerned about :(. Interested to hear if anyone knows a prophylactic measure....

[GPM]

Ya know Bob, I started to worry about the same thing. Since I have three relays jammed together in that little tray things were getting a bit crowded.

So, I pulled all the connectors off and soldered them all together. The Fire Department Captain recomended a great contractor. They should get started on the new garage next week.

:yahoo: :yahoo:

[jamming]

Bob, go to a hobby store, get some cyrocyanate glue, its basically super-glue on steriods. use just one TINY drop on the crimped side of the spade connector. It WILL be a permanant connection, you can unpermanant(is that a word?) by stealing some of the wifes fingernail remover, or acetone.
FYI. I use plain old Vaseline to prevent corrision, swap a bit on the connection.
BTW, unless you use a heat sink, if you solder the connection, it'll fry the relay. You could heat shrink over the connectors, and That's ok in Arizona, not sure I'd do it in a moist climate.

Roger

[TorqueMonsterMT-01]

Bob;
I am not an avianics guys, but have dealth with similar issues on commercial aircraft.

The best solution, and the one described oin many CMM (component maintenance manuals) is to build a fillet seal of RTV over the connection. It will keep corrosion out and due to the flexibility, it will prevent cracking and disrupted service.

I'll make a sketch for you, but I think you get the idea.

Cheers,
Jeff

[BobFV1]

Guys - thanks for all the input -

Roger, I suspected soldering might fry the relay - thanks for the confirmation.

Jeff - not quite sure about all the terms you are using - so I look forward to a sketch!

[TorqueMonsterMT-01]

http://r1150r.smugmug.com/photos/72087551-L.jpg

Bob,
This is common for commercial airline maintenance when the older connection types are still used.

It prevents moisture ingress that casues corrosion.

It relieves stress on the wire connection when the RTV is applied past the connector and onto the wire.

It prevents shorting against other connectors.


Yes, it is a little pain to remove, but not really bad. In the long run, it is worth doing to preserve the integrity of mechanical connections.

You can use any silicone sealant, but the red high temp stuff from the auto shop is the best.

Regards,
Jeff

[arkline]

Bob,

Use heat shrink for strain relief at the wire/spade solder connection and dielectric grease to retard corrosion.

[BobFV1]

Bob,

Use heat shrink for strain relief at the wire/spade solder connection

Check - I got that part - thanks Ron!

[TorqueMonsterMT-01]

Bob;
Certainly Ron knows of what he speaks. The creepy crawly guys (no offense Ron!) in the dark places below the floor of the 747s use the same techniques.

I use the silicone technique on fan reversers were the elements come into play. I have no idea how the elements affect your situation.

The good news is that you have a few options now.

[R4R&R]

Bob,
This is common for commercial airline maintenance when the older connection types are still used.

It prevents moisture ingress that casues corrosion.

It relieves stress on the wire connection when the RTV is applied past the connector and onto the wire.

It prevents shorting against other connectors.

Yes, it is a little pain to remove, but not really bad. In the long run, it is worth doing to preserve the integrity of mechanical connections.

You can use any silicone sealant, but the red high temp stuff from the auto shop is the best.

Regards,
Jeff

You know, that's what I did years ago on my Suzuki (I don't think the engineers planned on it being used year 'round in all weather, and my brake wiring kept failing....until....). I would re-crimp the connections about every six months and finally soldered/crimped them and kind of encased the crimps with silicone RTV. Never had to mess with them again.

My only problem is probably corrosion on the connectors eventually making a bad connection. I was thinking of a silicone electrical lubricant on the spades (I guess vasoline would work). In my case I don't think RTV is in order for the relay.

[arkline]

"The creepy crawly guys (no offense Ron!) in the dark places below the floor of the 747s use the same techniques."

No offense taken, I used to be one of those guys eeling around inside 737 wings as they were being built. Short and thin at the time, now I'm still fairly short, but not nearly so lithe...