CTS pot values question

Discussion in 'Tele-Technical' started by Chordophonic, Sep 13, 2015.

  1. Chordophonic

    Chordophonic Tele-Meister

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    Folks I have just received in the mail 2 x CTS pots - 1 x 250k log and 1x 250k lin, usually they arrive seaperately packaged in a little ziplok bag, marked A or B on the bag....these were in a bag together, there is nothing on the pot to suggest the value or taper.....grrrrrrr

    How can I tell whats what please?

    I do have a multimeter, but am not overconfident with it!

    Each pots is stamped thus

    45083468 1337 CTS
    45083468 1441 CTS

    I throw myself at the feet of the Guru's herein......

    Cheers!

    Paul
     
  2. Guitarteach

    Guitarteach Poster Extraordinaire

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    Does one not have a letter A on them for Audio (log) taper?

    The multimeter trick is to set pot half way. If it is linear it will read a resistance about half the value with pot set in the middle at either end terminal to the middle lug. A log pot will be quite a way off and one will be much higher.
     
  3. Chordophonic

    Chordophonic Tele-Meister

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    Thanks Teach!
     
  4. Guitarteach

    Guitarteach Poster Extraordinaire

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    The 4 digits are month and year. 37th of 2013 and 41st of 2014

    The other numbers are the same.... Mmmm

    Do they both read the same on the multimeter?
     
  5. Chordophonic

    Chordophonic Tele-Meister

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    Yes! Both read the same, I asked for 1 Log and one Lin, I reckon they have sent two the same and they are log! And thats why there were two in a bag, no need to pack seperately.....

    Thanks for you help! I've learned something today, including how to test resistance on the multimeter!

    Cheers!

    Paul
     
  6. Ripthorn

    Ripthorn Tele-Afflicted

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    On the PCB part right behind the lugs it should read A250k or B250k, with A being log taper and B being linear.
     
  7. dsutton24

    dsutton24 Doctor of Teleocity Ad Free Member

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    There's an easy trick to figuring out what kind of pot you have. Turn the pot to the mid point of the shaft's travel, you don't need to be terribly precise about this. Measure the resistance of the two outermost terminals, say 250k or so. Now measure from the middle terminal to one of the others. if it's about half of what you measured earlier, it's linear. If it's way off from half either way, it's audio taper.

    Here's more than you ever wanted to know on the subject:

    http://www.tdpri.com/forum/tele-technical/375039-audio-taper-linear-taper.html
     
  8. Guitarteach

    Guitarteach Poster Extraordinaire

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    Cool. You'll be building your own amps in no time now!
     
  9. Chordophonic

    Chordophonic Tele-Meister

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    Thanks for everyones input here…

    @ Guitarteach, I have already built an amp, an Ampmaker W55 kit, that's why I own a multimeter (!), I did a lot of Googling to work out how to test the Amp when it was built!….

    Paul
     
  10. Guitarteach

    Guitarteach Poster Extraordinaire

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    I've got that amp. It's really nice.

    Modded it to the max.
     
  11. Chordophonic

    Chordophonic Tele-Meister

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    I managed to build the Amp quite easily and modded it with a single tone control, but thats about my limit, anything else is right over my head!
     
  12. Guitarteach

    Guitarteach Poster Extraordinaire

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    Negative feedback switch (or pot) is like a presence control and some switchable cathode bypass caps to boost the gain are easy mods. I added a bright cap across the volume control lugs to give it some sizzle at low to mid volumes and a couple of resistor changes en route from input to V1. Next time I open it up I'm going to gang them as a 'bright mode'

    I also added a VVR recently, that was more involved but let's it distort really nicely at low volume now.

    Learned a lot.
     
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