slave receptacle contacts

[aslanperro]

I am planning to wire up the slave receptacle for my M38A1. Just to have idea before hand, I followed TM 9-1825e to use dowel and hammer to remove the 2 contacts inside rubber insert so they fell out from the rear.

Since I don't have the battery cable yet (I will have to order some 2 gauge cable), I tried to put the contacts back in the meantime. I used the dowel to hand push them in but it could only get flush with the insert at the rear. TM said the contact needs to be 1/8" recess from face on the insert. I had to hammer the dowel hard quite few times to achieve that. TM did say to use acetone etc as lubricant. I can't imagine when cable is soldered and just simply pushing with the cable can get contacts that far even with lubricant.

Is there some other tips or tricks to put contacts with cable soldered back inside the insert?

Thanks.

[RonD2]

Hey Anthony,
See the part of the pin that I highlighted yellow?



That's a low shoulder on the pin, but inside the hole it's a raised shoulder molded into the rubber. You might be able to see it with good light, or feel it with a small tool. That shoulder is what locks the pin into the rubber block at exactly the correct depth, when inserted properly.

When inserting the pins you have to be gentle to work the leading edge of the pin over the shoulder (with lubricant) to start them. A slight twist will usually help get over the edge. But don't force or press the pin over it or you can damage the rubber shoulder. If you're very very careful you can gently (gently!) press close the open end of the contacts on the leading edge to slightly reduce the diameter and help it ease by the shoulder and clear the rest of the rubber on it's way out to the front off the block. Usually only need to do that when re-using pins that tend to spread a bit naturally (not new ones). It's going to take some pressure and a slight twist or two, but after you clear the shoulder with the leading edge they should go in without too much fuss or fight. You might even "feel" them lock into place.

I don't recommend "parking" or reinserting the pins for practice until you have wire and are ready for final assembly. The less the pins go in and out of the hole over the shoulder the better off it usually goes.

The good news is your connector rubber insert looks new (plenty soft). Older hard ones like mine are a bear to deal with.

Plenty of dawn dish soap lubricant on a Q-tip over the entire length of the hole and a finger smear over the entire outside of the pin --- and make sure no crud anywhere.

Good luck!

[aslanperro]

Thanks Ron.

The leading narrower end of pin goes over the raised shoulder relatively easy. It is the wider portion of pin (the portion right in front of yellow highlight) that's real tight with the rubber insert.

I will solder the cables once I get them and try again with soap or acetone whatever helps.

[RonD2]

Hi Anthony,
Yes, it's supposed to be tight, especially on a new connector. Not sure how much experience you have with soldering heavy-gauge wire into pins, or whether you'll use a heavy iron or torch, but would add that pre-tinning the ends is an important step but can be tricky without a tinning pot (like the manual shows). Doubt you have a tinning pot but maybe you do have that old-school tool?

Obviously you need to be careful to make a sound electrical joint with solder, but avoid solder spilling over the edge of the cup and increasing the pin diameter which would make inserting it more difficult, especially if it flowed into the shoulder. The pins are pre-tinned and solder will want to flow all over it if you use too much. Be sure to use electrical grade solder not plumbers solder. When you get a good joint but maybe spill a little over the edge you can dress and polish it off with some fine sandpaper or crocus cloth.

When you go to insert them, it's important to try and keep them straight to the bore. Any cocking to the side off-center will make it challenging. Easier said than done with heavy gauge wire in a pin side-by-side with another pin.

Unless you keep acetone in your shop anyway I wouldn't spend $10 for a quart just to use a thimble full. Dawn dish soap is good, less hazardous, and can be flushed off with some WD-40 when you're done.

Just a thought, but soldering the wire into the pins is much better avoiding cold joints if you have three hands --- or a helper.

Let us know how it goes!

[aslanperro]

Yeah, not a tinning pot. I have torch and I have done other electronics soldering before with right kind of solder. Good idea to clean, polish the contacts afterward to help a smooth insert. Thanks again.

[aslanperro]

Got cables and lugs. Used 1/2" copper cap as my miniature tinning "pot" Soldered all ends and cleaned contacts.

First, I slathered both contact and insert hole with soap to help pushing the contact and cable into the rubber insert. But it was short by ~5/8" and it couldn't advance any more. You can tell the photo below that the cable started to buckle instead.

So made a trip to local store and bought a quart of acetone. Brushed both contact and hole. Pushed contact and cable in and wa-lah it went in much easier. I don't know if because this rubber insert is still "new" and soft or what's the chemistry between it and acetone. But it's real different. Now I have 30 oz of acetone left over , for next paint job clean up.

Thanks again for inputs.