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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 11th Nov 2023, 1:09 am   #1
Julesomega
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Default Re-plasticising croc-clip shrouds

.. or boots or whatever you call them. We all have test leads of flexible cable with insulated crocodile clips on the end which we use for simple tests like applying power to a 2-terminal component, but after a decade or two the boots start to harden up until they are too stiff to open the croc clip between finger and thumb. The other day I was trying to use such a croc clip which I couldn't open so I tried boiling water and it softened up beautifully, but once cool the clip wouldn't close to grip the test item

They obviously lose the plasticiser, presumably being made of PVC, and a quick google for DIY PVC plasticiser drew a blank so I added a small amount of light '3-in-1' type machine oil to some xylene in a jar and submersed the lead for about five days. The result was a brand new insulated croc clip, and the extra-flexible test lead cable was also in good condition.

I know there are people who understand polymers and elastomers, so I would be pleased to learn any suggestions for improving this technique.
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Old 11th Nov 2023, 11:23 am   #2
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Default Re: Re-plasticising croc-clip shrouds

Household glycerine works well on some types of synthetic rubbers. I haven't tried it on plastics. On the rubbers I have successfully used it on, flexibility returned after a few minutes.
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Old 11th Nov 2023, 1:46 pm   #3
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Default Re: Re-plasticising croc-clip shrouds

I've had this problem too. Xylene thinners is wicked stuff though, clears the old nostrils out for sure. I read that brake fluid works too, but never tried it.

Andy.
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Old 11th Nov 2023, 2:22 pm   #4
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Default Re: Re-plasticising croc-clip shrouds

I would buy another bag of cheap patch leads from the flea market and use the best of the clips with the insulation from the new ones.
They eventually go open circuit just behind the clips anyway so you had might as well take that opportunity to replace the insulators at the same time.
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Old 11th Nov 2023, 3:15 pm   #5
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Default Re: Re-plasticising croc-clip shrouds

Brake fluid formulations have changed over the years. The Castrol Girling Crimson that was widely used in the 1970's made excellent paint stripper for removing oil-based paints from polystyrene. The modern stuff doesn't touch it.
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Old 11th Nov 2023, 5:48 pm   #6
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Default Re: Re-plasticising croc-clip shrouds

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I would buy another bag of cheap patch leads from the flea market and use the best of the clips with the insulation from the new ones.
They eventually go open circuit just behind the clips anyway so you had might as well take that opportunity to replace the insulators at the same time.
Yes, I consider these things to be 'consumables', and when they go high-resistance or the covers get stiff I happily dump them in the woodstove and order up another bunch from the Internet Bazaar-of-tat.
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Old 12th Nov 2023, 1:02 am   #7
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Default Re: Re-plasticising croc-clip shrouds

Yes, much better to buy a few in advance of a project; it's just not worth the trouble of unsoldering old croc clips or soldering new ones, but if you have some decently made ones that have gone crunchy it's worth a try. Xylene is cheap these days and seems to be the preferred thinners and cleaner for the new water-soluble paints, of which I'm a great fan!

Wonder if I've got any glycerine...
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Old 14th Nov 2023, 1:02 pm   #8
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Default Re: Re-plasticising croc-clip shrouds

Last bunch of cheap croc-clip leads I bought for the kids were a bit disappointing, the wire gauge was terribly thin, and they weren't soldered, instead the bared core was bent backwards over the insulation and the strain relief of the clip was just squashed down on the lot.

Ok for small signal use, but would get hot quickly given any current...

But yes, I have a scope earth lead with a hardened croc clip shroud. makes it almost impossible to use. Thanks for your top-tip! But as I have no xylene I may just steal one of the cheap croc clips from a lead and replace it!

Ie; be careful what you buy online cheaply.
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Old 17th Nov 2023, 10:02 pm   #9
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Default Re: Re-plasticising croc-clip shrouds

Quote:
consider these things to be 'consumables
That's one way of looking at it, but isn't our ethos, as a whole, on this forum, the preservation & restoration of electronic devices? Yes it's only a £2 little bit of metal & plastic but I hate chucking stuff away when I can give it a new life, waste not want not as my Granny used to say.

Andy.
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Old 18th Nov 2023, 4:40 am   #10
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Default Re: Re-plasticising croc-clip shrouds

You do have to look at the cost of the solvent used to soften the plastic again.
New ones do stand a chance of being cheaper.
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Old 18th Nov 2023, 11:46 am   #11
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Default Re: Re-plasticising croc-clip shrouds

The replacement vs. refurbishment debate can easily overlook the sheer PitA of soldering to a new nickel-plated component, not to mention releasing the lugs that grip the cable as it emerges; I wanted also to reuse the valued length of multi-strand extra-flexible test lead of the chosen colour. I recently bought very cheaply a pack of croc-clip leads in assorted colours, but these will in turn harden up and need soften, though not necessarily in my lifetime
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Old 19th Nov 2023, 7:46 pm   #12
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Default Re: Re-plasticising croc-clip shrouds

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The replacement vs. refurbishment debate can easily overlook the sheer PitA of soldering to a new nickel-plated component, not to mention releasing the lugs that grip the cable as it emerges; I wanted also to reuse the valued length of multi-strand extra-flexible test lead of the chosen colour. I recently bought very cheaply a pack of croc-clip leads in assorted colours, but these will in turn harden up and need soften, though not necessarily in my lifetime
Yes, the one thing always at the back of my mind is that the most-valuable and non-renewable resource is the remaining years of my life.

Messing around spending an hour or more of my life reworking/recovering cheap trash-spec croc-clip-leads seems to me to be a bad 'investment' of my time, when I can get some new ones delivered next-day for a tenner and spend the hour so freed-up on something more enjoyable.
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