Electronic – Why do some wires in the turntable have plastic covers over them

wire

I recently purchased a turntable. I spent a good chuck of cash on it – and it sounds great but has trouble keeping speed.

I am starting to retrofit it with a brush less motor that will be controlled by an Arduino. When I opened it up the first thing that jumped out at me was that some of the wires were covered by a plastic tube that is pretty nasty and looks like it has been accumulating condensation for the last 40 years.

Why are these wires covered in an extra layer of plastic? Would it be ok for me to just replace the wires?

Here's a photo of what it looks like.
enter image description here

Best Answer

I would guess that the sleeving is for extra electrical insulation. I see in your photo that these wires are passing near the fuse holder, so they may be part of a secondary-side circuit and due to the physical construction of the turntable are forced to pass near / across the normal isolation barrier between primary and secondary.

For these sorts of things, I tend to look at it this way: if the original manufacturer went to the trouble / expense of putting sleeving on these wires, it's probably necessary, even if the reason may not be readily apparent.

If you want to replace the sleeving for aesthetics, I'd think twice. If the sleeving is starting to become brittle and break down, or is cracked, by all means replace it, or shore up the weak sections with several turns of electrical tape or Kapton tape. If you are really compelled to replace it, try and find similar thickness material that is appropriate for electrical insulation (e.g. PTFE / Teflon).

If you really must replace the wires and don't want to sleeve them, make sure that the wires you're using are at an absolute bare minimum rated to 600V insulation. (Don't use regular 150V or 300V appliance wire - get the good stuff.)

(Even with 600V wire, I'd still put sleeving on them. Yes, I'm paranoid, but I also do this sort of stuff for a living. I've seen many "interesting" dielecrtic breakdown failures during safety testing of the products I've developed, and have had to insulate things that I never thought were "insulatable.")

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