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Problem hard wiring decoder


ColinK
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I have just started hard wiring a decoder for the first time and have encountered some problems, I hope someone can help. On this RTR loco chassis it simply isn’t possible to solder the decoder wires onto the pick ups and motor.  All I have to do is join the four wires from the decoder with the two wires from the pick ups and two from the motor.  

 

The first problem is how to strip the insulation off the very fine decoder wires?  My wire strippers simply cannot manage such fine wire. Indeed I’ve accidently shortened the wires trying.

 

Having finally got some insulation off, how do you actually make a strong connection between the two wires, in effect it is a soldered but joint?  Make little hooks on the end of each wire? Try and twist them round each other?  The actual soldering is no problem.

 

I slid some heat shrink onto one the wires, but on my first attempt at joining the wires, enough heat travelled down the wire and shrunk the heatshrink before I could get it over the joint (I’ve used liquid insulation tape instead.  On the second attempt the wire came unsoldered off the motor, fortunatly this motor terminal is accessible, the other one is not.

 

Cheers.

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For stripping small (or most) wires, I just use good quality side cutters.

 

These Toolcraft ones are pretty good quality, for the price. I've used them for fine work for several years.

https://www.ebay.co.uk/itm/Toolcraft-816744-Electronic-Diagonal-Cutters-No-Facet-128mm/131133775368?epid=1428922468&hash=item1e882e9e08:g:~R4AAOSwNmxb7kbP

 

Or these from RS; they are rather heavier duty, very good when new but I tend to use them for large cables as well, so the blades get chewed up after a while.

https://uk.rs-online.com/web/p/cable-cutters/0536329/

 

Make sure you get a type like those with "flush cut" blades (what they call no facet in ebay listing - see the inset of the blade profile in the ebay article), not angled at both sides like a typical larger wire cutters.

 

If you gently nip the wire with the flat side of the blades towards the wire end and just pull towards the end, it should strip. Unlike double angled blades, they dig in and grab the insulation very easily, with little "grip" force needed.

 

It may take a bit of practice so try on some scrap wire first.

 

To join fine wires, strip about 1/4" or 5-6mm of each, twist the stripped ends (with both ends facing the same way), solder then straighten the wire so the soldered joint lays flat against the insulation at one side or the other. Then insulate the joint.

 

[Electronics designer & manufacturer for over 40 years].

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