Brown Coating on Resistor Lead

[Proschuno]

So ripping apart a television (a casual Thursday afternoon activity…), I've come upon a bunch of these resistors with a brown coating on one lead; at first regarding it as rust, none of the other components are rusting (this was found outside my local garbage dump in my apt. complex, and it just rained when I picked it up…), and also noticing that it glimmers a little on the bottom right of the picture (rust wouldn't do that..). Trying to measure the resistance through it the meter measured infinitely high, but touching the actual metal gave an accurate measurement, and none of these seem faulty.

 

[Proschuno]

Sorry here's the photo...

 

[Raven Luni]

Its laquer and its purpose is to insulate the resistor lead. I'm guessing the resistor was stood upright with that lead folded down. Its basically just to protect it from accidental contact with other parts of the circuit.

 

[Proschuno]

It was, forgot to mention that. just found it very interesting, after busting into hundreds of other appliances without ever seeing that on bent resistor leads like that….

 

[jpanhalt]

I agree, it is a man-made coating. Whether it is lacquer, enamel, PVC, etc. doesn't matter. I would have expected a lacquer coating to be more conformal at the sharp bend.

In any event, it is not rust (I don't think leads on resistors are steel/iron) or any other product of oxidation.

John

 

[(*steve*)]

Possibly a very thin heat-shrink tube used to insulate the lead. I imagine the resistor was mounted standing up. Whatever it was next to, the designer didn't want this shorting out with it.