RadioBanter - View Single Post - Damaged resistor

April 15th 06, 05:03 AM posted to rec.radio.amateur.homebrew

wrote:

I have a carbon film resistor that got so hot that it melted itself
free of the circuit board. Can the resistance (of the resistor) be
permanently increased when this happens or does a resistor just become
"open" when that happens? The reason I ask is because I have two
resistors in parallel that go:

Black | Brown | Black | Gold

I think the resistance should measure ~1/2 Ohm, but my ohm meter reads
33 Ohms. Does this mean they are damage or did I do something wrong?

Thanks,
Scott, KC2PIH

Usually when I do that the color code becomes Black | Black | Black | Black.

Yes, if the resistance element burns off a bit without going completely
away the resistance can rise. In your case I suspect that you're
measuring other resistances in the circuit. Even if you're measuring
the actual resistance, 66 times the design value may as well be open.

You need to replace the resistors, and before you do that you need to
find and clear whatever fault it was that made them char.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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