Testset Connector Reinforcement

@gunrunnerjohn posted:

Anyone know what is used for this reinforcement on test set connectors?  This is from the MTH PS/2 testset, and I've seen it in other places.

Dunno, John. From the appearance, it looks like it's made of some sort of textured translucent plastic, and from the slight tapering at the wire end, it appears to have some shrink-wrap qualities. From the pic, it's not entirely clear how (or if) it's anchored at the connector end, but I'm assuming it *is* anchored in some fashion -- otherwise, it's just a glorified wire wrap. Never seen one quite like it.

Are you just curious, or are you looking to repair/replace one?

@Steve Tyler posted:

Dunno, John. From the appearance, it looks like it's made of some sort of textured translucent plastic, and from the slight tapering at the wire end, it appears to have some shrink-wrap qualities. From the pic, it's not entirely clear how (or if) it's anchored at the connector end, but I'm assuming it *is* anchored in some fashion -- otherwise, it's just a glorified wire wrap. Never seen one quite like it.

Are you just curious, or are you looking to repair/replace one?

It's not anchored to the connector, but the fact that it's bonded to all the wires makes it much easier to remove the connectors from the board without pulling a wire out of the connector.  It's obviously put on in a soft form and hardens, something like RTV, but I'm not sure what kind of material it is.

I want to use the same thing on my testsets to make the connectors easier to remove and insert.

@gunrunnerjohn posted:

It's not anchored to the connector, but the fact that it's bonded to all the wires makes it much easier to remove the connectors from the board without pulling a wire out of the connector.  It's obviously put on in a soft form and hardens, something like RTV, but I'm not sure what kind of material it is.

I want to use the same thing on my testsets to make the connectors easier to remove and insert.

Hmm . . . as I was scratching my head about your initial post, I had the passing thought that I've seen hot glue (or something similar) used to bond soldered-in wires to the circuit board, relieving some of the mechanical tension that would otherwise have to be borne by the soldered joint if the wire was moved. It might look a lot messier than your pic, but you might be able to get much the same effect if you slather hot glue around and between the wires and the connector, mechanically bonding them all together. I suppose if you wrapped the hot glue-and-wire bundle with some sort of plastic wrap and pressed it in before the hot glue cooled, you could end up with something that didn't look *too* bad that would allow you to safely pull the connector out by the wire bundle.

I have tried hot glue for that very purpose.  It worked OK, but not as neat as whatever this stuff is.

It appears to be this stuff.
High-Shrink-Ratio Heat-Shrink Tubing
    Dielectric Strength: 455 V/mil
    Shrink Temperature: 660° F
    Temperature Range: -450° to 500° F

This tubing shrinks down to a quarter of its original ID, so it creates a tight seal over irregularly shaped objects. Made of PTFE, it withstands temperatures up to 500° F and resists abrasion and chemicals.

Dielectric strength is the maximum voltage a material can handle before it starts to breakdown.

@Susan Deats posted:

It appears to be this stuff.
High-Shrink-Ratio Heat-Shrink Tubing
    Dielectric Strength: 455 V/mil
    Shrink Temperature: 660° F
    Temperature Range: -450° to 500° F

This tubing shrinks down to a quarter of its original ID, so it creates a tight seal over irregularly shaped objects. Made of PTFE, it withstands temperatures up to 500° F and resists abrasion and chemicals.

Dielectric strength is the maximum voltage a material can handle before it starts to breakdown.

I followed Susan's link and then went down the rabbit hole of "What is PTFE?"  Turns out PTFE is a carbon and fluorine synthetic polymer – Polytetrafluoroethylene.  Also known by the brand name, Teflon.

Bob

John, I make test connectors similar to this for fuel injection harnesses, OBD2 testers, etc, etc, ….I use normal heat shrink tubing and clear silicone, ……put a dab around the header connector where the wires go in, slide the heat shrink up & over, wipe up any excess, wait about 15-20 minutes for the silicone to skin over, then shrink the tubing, when the silicone fully cures, it’s a tough, strong test plug that can be tugged on hundreds of times. …..sometimes I might use two sizes of heat shrink depending on the wire bundle …..one to surround the plug, and another that surrounds the wires neatly, but also bridges the larger one ….small tube of clear silicone is plenty cheap enough, and only cut a tiny hole in the tip so you can control ooze,….

Pat

@Susan Deats posted:

It appears to be this stuff.
High-Shrink-Ratio Heat-Shrink Tubing
    Dielectric Strength: 455 V/mil
    Shrink Temperature: 660° F
    Temperature Range: -450° to 500° F

This tubing shrinks down to a quarter of its original ID, so it creates a tight seal over irregularly shaped objects. Made of PTFE, it withstands temperatures up to 500° F and resists abrasion and chemicals.

Dielectric strength is the maximum voltage a material can handle before it starts to breakdown.

Susan, when you look at it up close, it's clearly not heat-shrink.  It has formed around the wires and isn't squeezing them at all.  If it were 4:1 heatshrink, it would look totally different.

@harmonyards posted:

John, I make test connectors similar to this for fuel injection harnesses, OBD2 testers, etc, etc, ….I use normal heat shrink tubing and clear silicone, ……put a dab around the header connector where the wires go in, slide the heat shrink up & over, wipe up any excess, wait about 15-20 minutes for the silicone to skin over, then shrink the tubing, when the silicone fully cures, it’s a tough, strong test plug that can be tugged on hundreds of times. …..sometimes I might use two sizes of heat shrink depending on the wire bundle …..one to surround the plug, and another that surrounds the wires neatly, but also bridges the larger one ….small tube of clear silicone is plenty cheap enough, and only cut a tiny hole in the tip so you can control ooze,….

Pat

That would be totally different Pat, but it does sound like that would be an effective way to add the reinforcement.

@harmonyards posted:

John, I make test connectors similar to this for fuel injection harnesses, OBD2 testers, etc, etc, ….I use normal heat shrink tubing and clear silicone, ……put a dab around the header connector where the wires go in, slide the heat shrink up & over, wipe up any excess, wait about 15-20 minutes for the silicone to skin over, then shrink the tubing, when the silicone fully cures, it’s a tough, strong test plug that can be tugged on hundreds of times. …..sometimes I might use two sizes of heat shrink depending on the wire bundle …..one to surround the plug, and another that surrounds the wires neatly, but also bridges the larger one ….small tube of clear silicone is plenty cheap enough, and only cut a tiny hole in the tip so you can control ooze,….

Ding, ding, ding . . . I think we have a winner!

While I agree with John that this does not appear to be the precise solution shown in his pic, I think it is by far the best solution yet proposed to achieve the goal. Prior to final hardening, the silicone should be flexible enough to bind all the insulated wires and connector together into a single mechanically stable unit, as proven by Pat's success with the technique. The final result would no doubt look somewhat different than what was depicted John's pic, but for something that likely will *only* be visible when its mechanical properties are needed, ISTM silicone and shrink wrap should be an elegant and inexpensive solution.

Remember, the connector bodies can NOT be thicker than they already are, they fit into the connector shells on the PCB.

I've got very large shrink wrap that was sent to me in error. It's a purple/blue color but it is flat and looks something like that pic.

I wonder if that's just a clear version of it?

I've use it for large sound system cabling.

Maybe it just has the silicone in it like Pat suggests?

Then, maybe it's not fully shrunk. Just enough to clamp down on the silicone.

It's not heatshrink, that I can say for sure.  It's some kind of material like RTV, only with an odd texture.  I'll probably just ad-lib with something like RTV.

I always wondered similar thing.  The MTH Test cables hold up very well over years and years of utilizing them.

Jim

@Jim Sandman posted:

I always wondered similar thing.  The MTH Test cables hold up very well over years and years of utilizing them.

Yep, my PS/2 test-set is 11 years old now, and they've been used a lot, but I haven't had any issues with the cables.  I'm actually a bit surprised, I expected by now to be having to repair/replace at least one or two of them.  I will say that at some point I expect the connectors to wear out, they're rated for 50 plug/unplug cycles!