Author Topic: Fitting UK style plug to older cable  (Read 293 times)

Offline royalbox

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Fitting UK style plug to older cable
« on: December 22, 2018, 09:44:08 AM »
Hello,
I'm looking for a way to fit a UK plug and socket type plug onto an old trimphone cable. The inner individual wires are too flexible and also laid out in the wrong order and I've spent a lot of time and effort trying to fit one with no success.

What I've tried: Getting them in the right order by overlapping and putting a piece of heatshink tubing over them where they meet the outer cable sheath.

More unnecessary detail: It already had the correct plug on it but there was no continuity on the blue and (unused) green lines and so the phone didn't ring. I cut off the plug and stripped back the cables and got continuity so assumed it was not a good connection on the plug.

Thanks for any suggestions.

Offline royalbox

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Re: Fitting UK style plug to older cable
« Reply #1 on: December 22, 2018, 09:52:25 AM »
This is it after ripping it back out of an unsuccessful attempt so you can see what I tried:

Offline RB

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Re: Fitting UK style plug to older cable
« Reply #2 on: December 22, 2018, 10:27:21 AM »
pics of the plug would help :)

Offline royalbox

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Re: Fitting UK style plug to older cable
« Reply #3 on: December 22, 2018, 10:46:39 AM »
It's a standard UK 431A. I bought clear ones so I could see if the wires had gone in correctly. This is a top down view, the cable goes in from the left.

Offline Jim Stettler

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Re: Fitting UK style plug to older cable
« Reply #4 on: December 22, 2018, 11:01:20 AM »
In the US the mod conductors are different for stranded vs solid wire, It is different where the conductor pierces the wire. They are also different for flat vs round cable, you can tell by looking at the connector. It will be shaped round or flat.

I have crimped a handset cord that was this set-up, a round stranded cord. It is tedious to get it done right, it took a few tries to get  it right.

I would suggest holding the plug in a vise or clamp, and using tweezers to line up the conductors. A lighted magnifier helps.
Once you have the wires in the plug you still need to crimp it, which means removing it from the vise, and positioning the crimper without pulling the cable from the plug. It will require patience and multiple tries to get it done right. It helps to be relaxed and take your time. If you start getting frustrated, take a break.
Once you have it done, cross your fingers and test it. If it test ok then you are done, If it doesn't start over.

If the original  plug was still on the cord, sometimes you can just recrimp it to get it working, however I feel that is just a short term fix.
Good-luck
Jim S.
You live, You learn,
You die, you forget it all.

Offline royalbox

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Re: Fitting UK style plug to older cable
« Reply #5 on: December 22, 2018, 11:26:57 AM »
Thanks for the advice, much appreciated. Holding it in a vice is a good idea, don't think I could get tweezers in there though unfortunately.

I don't have a proper crimping tool, the plugs I bought came with a plastic piece that you align on top of the plug and squeeze with pliers. This is now broken however and I had to resort to pressing down on each connector with a screwdriver blade. If I were doing this regularly I'd get a crimping too but although not that expensive, they're more than I paid for the phone and I may never use it again.


I was wondering if there was something you could "paint" on the wires to make them stiffer but then I'd have to buy whatever it is anyway so not worth it.

I have one more plug left so will give it a go in the vice but will need to strip the wires back again and redo the heatsink.

Thanks again.

Offline twocvbloke

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Re: Fitting UK style plug to older cable
« Reply #6 on: December 22, 2018, 12:32:59 PM »
One of the issues I've found with using original cables in BT plugs is the insulation on the originals is a bit thicker than what the plug is meant to accept, so makes it a PITA to crimp onto. The best solution to retain original wiring is to have the original cable terminated with spade lugs in a BT52A, then connect a modern replacement GPO style cable from that with a BT plug on the other end... :)

Offline Key2871

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Re: Fitting UK style plug to older cable
« Reply #7 on: December 22, 2018, 02:21:48 PM »
I remember, early in my phone work, I also tried to re crimp a modular plug with zero success. I broke down and bought a crimper and a good one at that, because the cheap ones don't work right after a little while.
Jim was correct, as with another, the insulation on the older cord will never go into newer mod ends, way too thick. Your best bet is to find a modular cord, solder the wires on from the old cord to the new one. A small piece of heat shrink and your good.
KEN

Offline Jim Stettler

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Re: Fitting UK style plug to older cable
« Reply #8 on: December 22, 2018, 05:25:58 PM »
BTW cut the conductors flush and use smooth conductors. (cut back the jacket if needed or able). That helps a lot.
Jim S.
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You die, you forget it all.

Offline andy1702

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Re: Fitting UK style plug to older cable
« Reply #9 on: December 23, 2018, 11:03:26 AM »
Fitting a BT type plug onto an old trimphone wire is sometimes possibe, but it's not easy and sometimes can't be done at all. The first thing to decide is what type of cable the phone has. The GPO / telecom used two types of line cord in their phones over the years. The early type was quite thick and there is no way to get it into the plug. Even if you cut away the outer cover, the four conductors are each too thick to go into the individyal holes inside the plug, so there's nothing you can do with that cable to fit a plug directly.

Later phones however used a much thinner round cable. You still probably won't get the outer covering unside the plug, but theindividual conductors will go up inside the individual holes with a bit of effort. What I do is strip about 2 inches of the outer cover off the cable, then shove 2 inches of heat shrink over the ends, push it down the cable and forget it for a bit. Now you've got 2 inches of individual conductors showing. This should be enough length that you can sort them into order and lay them out flat. good electronics shops wills ell you an aerosol can of freeze spray, which you can spray onto the wires to make them a lot more rigid. Holding them flat between your thumb and finger, push them up inside the plug and crimp into place. There will still be a good inch of the individual conductors showing pout of the end of the plug. Slide that heat shrink you put on earlier right up so it buts up against the plug and shrink into place.

I've done this a few times, but it's very fiddly, so these days I tend to change the whole line cord.
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Offline Jim Stettler

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Re: Fitting UK style plug to older cable
« Reply #10 on: December 23, 2018, 02:20:55 PM »
Instead of a vise, like I stated earlier. It may work easier  to use a jack as your holder.
Jim S.
You live, You learn,
You die, you forget it all.

Offline royalbox

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Re: Fitting UK style plug to older cable
« Reply #11 on: December 24, 2018, 08:02:16 AM »
Thanks for all the advice everyone, really appreciate it.

The cable is the thinner round cable that does just go into the socket. I have a phone with the thicker cable so I know that it's not possible with those.

In the end I couldn't get all the wires to go right to the end of the plug, they always bent up before getting there. Usually one or two got there. I even swapped the green and blue so they lined up better.

As I wanted to test the phone I drilled a hole in the top of the plug so I could push the wire in with a small screwdriver. I got then in enough and pressed the contacts down with a screwdriver as I have no clamping tool. It did work and the phone rings now but it's a temporary bodge.

I ordered a cheap new cable at under 1 inc postage from ebay and will perhaps go for the jointing them together method and covering with a bit of shrink tube. I've run out of plugs now anyway.

Thanks again all.