CEV switches

CDHE

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Boulder, Co
Hello, Has anyone out there monkeyed with old CEV switches? I recall reading that it is best to use conductive epoxy to attach wires as the most careful soldering is likely to end in heartbreak? Does this make sense?
 

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Hello, Has anyone out there monkeyed with old CEV switches? I recall reading that it is best to use conductive epoxy to attach wires as the most careful soldering is likely to end in heartbreak? Does this make sense?
Yes the black plastic almost melts instantly, so better not to solder and use the tiny screws to attach wires. I do recommend to solder the ends of the wires to give the fixing screws more grip.

Marnix
 
Yes the black plastic almost melts instantly, so better not to solder and use the tiny screws to attach wires. I do recommend to solder the ends of the wires to give the fixing screws more grip.

Marnix
This can also make the wires more prone to break due to vibration or the fitting to loosen? Has been discussed here on the forum. Bare wires was the recommendation iirc.
 
Applying solder to the end of the wire before tightening it under a screw prevents the strands from spreading and moving away from the area of pressure. This makes a far better connection.
Solder also spoils the flexibility of the wire so makes it prone to fatigue cracking.
I often use solder to improve a joint but always ensure the joint is well supported against vibration, eg by the clamps in a switchblock.
 
As you say Andy, though it is a "solder" first before compression fitting is not acceptable in industry, basis being the tin/lead type solder will cold flow under compression, post solder again on a compressed fitting can be used, as it fills the voids and prevents cold flow as such. Crimped bootlace or ferrule first on fly wire, then under screw compression application. Alleviates the well pointed out attachment fatigue consequence of rigid solder to wire union.

As for soldering wires to thermoset plastics, soldering iron plays the most significant factor, mains powered soldering irons are going to cause problems. have 6 soldering irons for different tasks here, soldering 1m/m smd parts to large copper layers which draw heat away form the iron. Technique is all, takes skill soldering onto thin flexible plastic "ribbon" like interconnects.

Eutectic temperature of usual grade 60/40 roll solder is 240C, that is a minimum, around 340C for the actual iron tip temperature prior to application to the parts to be soldered. HTH j.
 
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