Electronics > Beginners
Identifing a Potentiometer
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SuperDaveOsbourne:
I have a Sencore Capacitor Analyser Model CA55 that has a bad front panel leak zero adjust potentiometer. See pictures below, the resistance track is 100% destroyed.

This does bring up the first question,  can I tell what it is by the numbers on the case of the pot? I see Mouser has all kinds of series but I don't see there is a standard to see what this baby is. The schematic is shown on a YouTube video but not close enough to see.  This is just a standard single gang pot with three lugs with two tied together. I would call it a micro panel mounted pot.

Is there some kind of standard?

Stamped on the case 1377913 15B8-5

Shaft dia .1260in 3.15mm
Shaft length beyond collar  .21in 5.5mm
Collar length .20in 5.5mm
Collar dia .20in  6.15mm
Case dia .62in 15.5mm 
Brumby:
My Google-fu hasn't been particularly successful - but it seems you can get a hold of a service manual ... for a fee.

Without that, I'd be looking for some other markings.  A photo could help as there are a few people here that have seen enough components to be able to offer some useful comments if they could actually see the pot.

With the wiper having fallen off, you might be unable to determine the resistance profile (log, linear, anti-log, etc.) but you should be able to identify its total resistance.  Just measure the resistance between the two outer lugs (this will be more accurate if out of circuit).

With a loose wiper floating around, it might be an idea to tip the pot around in different orientations and give it a shake so as to make sure the wiper isn't shorting anything internally and take some more measurements to confirm.  As a final step, I'd suggest cutting the connection between the two joined lugs to minimise the possibility of something shorting inside that will affect the measurement.

Once you have this measurement, get a hold of a couple of (garden variety) pots with this resistance (or slightly more) in linear and log (these are the most common tapers) and try each of them in turn to see which functions as closely as the original.  Armed with the resistance and taper, you can then focus on getting a mechanical match ... with the quality of the movement you need.
SuperDaveOsbourne:
Images of the pot.

I just ordered the caps to recap this so it will be a little while before I can test it. Also I have to run down the low capacitance leads. I saw a listing for someone selling them for the CA-55 off Google but I can't find it today. They were selling the cables for 30$.
djnz:
I found this:

https://www.westfloridacomponents.com/P042APF06/10K+ohm+Potentiometer+CTS+1377913.html

My best guess would be that CTS 1377913 are all 10k pots and the other numbers specify the type of terminals / mounting style etc.


Brumby:

--- Quote from: djnz on August 25, 2018, 01:33:07 am ---I found this:

https://www.westfloridacomponents.com/P042APF06/10K+ohm+Potentiometer+CTS+1377913.html

My best guess would be that CTS 1377913 are all 10k pots and the other numbers specify the type of terminals / mounting style etc.

--- End quote ---

I found that too - but I'm not sure I would make the same conclusions.
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