Looking for a potentiometer for restoration project

Wayne S Wayne.Sudol at hotmail.com
Tue Jan 19 18:17:56 CST 2021


Just for clarification, a pot has 3 tabs. Ohmeter measuring across the 2 “end” tabs should indicate the total resistance of the pot (10k, 50k, 500k ohms, whatever the schematic says). If the measurement is infinite then the potentiometer is open broken. If you get that reading, you might want to open one end of the pot and remeasure just to be sure. 
If it measures close to the schematic value then measure one of the ends and the center tab and rotating the potentiometer should show different values as it’s rotated. Also measure the other side to the center and see if the values change in the other direction. Potentiometers are just an exposed piece of carbon ( or wirewound) with a wiper blade (the center tab) going across it. Sometimes the solid piece of carbon can break causing the open condition, but still providing somewhat variable resistance. 
It’s been my experience in repairing televisions that the brightness control rarely goes bad it’s usually some other component in the brightness circuit and a lot of times it’s just an aging CRT.
 
I wasn’t able to see the pictures because you need to be a member of vcf.

Sent from my iPhone

> On Jan 19, 2021, at 15:36, Ali <cctalk at ibm51xx.net> wrote:
> 
> 
>> 
>> 
>> Out of curiosity, why do you think the pot is bad?
>> 
>> Wayne
>> 
> 
> Wayne,
> 
> I could be totally wrong here (EE definitely was not my major) but
> 
> 1. Turning the pot does not change the brightness of the screen at all
> 2. Measuring the pot and adjusting it (i.e. turning the knob) gives me a constant resistance reading. Doing the same thing with the volume pot gives me a range of resistances as expected.
> 
> If my thinking is wrong or I should be doing another test I am open to hearing it.
> 
> 
> -Ali
> 


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