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Potentiometer help

Breney

Oct 15, 2014
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Oct 15, 2014
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I'm trying to repair a CB radio, a TCB660. The squelch dial is broken, continuously turning but not having an effect: I'm replacing the potentiometer. There are no markings on it or the circuit board that relate to a value or model etc.... Could anybody help identify it - it has 3 pins and a splined shaft. Reading from a multimeter shows a max resistance of 1500ohm over the full range. However I am in doubt over this value. What would a correct value be for a potentiometer for CB radio squelch?
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
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Nov 28, 2011
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Hi there and welcome to Electronics Point :)

There is no typical or standard value for a squelch potentiometer; it depends on the circuit design.

Remove it from the board and measure between the two end terminals. If it's not too badly damaged, that will tell you its resistance.

Potentiometers also have a "law" - usually linear or logarithmic - which relates to the way the resistances change as it is rotated. We may be able to tell you how to determine the old potentiometer's law if you dismantle it carefully and upload a photo of the parts.
 

Breney

Oct 15, 2014
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Oct 15, 2014
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I have found a pdf of the service manual for the radio. It has schematic diagrams, parts list etc... The part I'm looking for in it is SQ101. Could anyone see it in the schematic and calculate its value and law. I think it might be 50KΩ linear
 

Harald Kapp

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Nov 17, 2011
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Could anyone see it in the schematic and calculate its value and law. I think it might be 50KΩ linear
If you provide the schematic (or an excerpt from the schematic showing the potentiometer), we might be able to do so.
 
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