Armature Bar Functioning

[lamfdtk]

Since coil machines work with the on/off cycle of the magnet, what would cause a machine that has been running nicely for a couple of
hours to suddenly lock the arm.bar down onto the front coil? Is it something to do with pos/neg flow? I have couple of clipcords that unless
I am missing something,is almost impossible to tell which is the positive and which is the negative terminal.

[Ramenuzumaki]

Personally I don’t use bunny-eared clip cords. I use RCA. However, when I did use them it didnt really matter–in my experience–which was on top, and which was on the bottom.

What is causing it–I assume–is poor insulation. I’ve seen this before in machines I’ve purchased that were missing an insulation washer. The A-bar drops, but doesnt come back up. You need this insulation to break the contact with the cap otherwise it’s constantly getting powered, and your A-bar wont rise again. It could also be an issue with your contact screw. Check your spring, and the tip of the screw. Do they look dark/burnt? Sometimes if the machine gives off sparks, and such it will cause a build up on your coil/spring. If you use emery cloth/board–be sure its emery, not your average nail file–and gently/carefully get rid of this build up. Don’t go too deep as you could damage your contact screw.

The difference between a regular nail file, and an emery board is that emery boards have small shards of glass rather than sand on them. The glass will not heat up with the friction as you do your work. I normally keep an emery board in my shop at all times for times like this.

You can also check to make sure your contact screw isnt loose. I’ve seen people use the wrong screws where you can slide them back and forth without twisting them. That’s no good.

So:
1. Check to be sure your screw doesnt move without being turned
2. Check your screw end/spring contact for any build ups
3. Check your insulating washers, and replace any damaged ones.

Let me know if this helped at all.

[Author]

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