I have a 1986 Gibson Les Paul Custom. Looking into the control cavity, I see that all four potentiometers are stamped R1378511. The two tone pots also have the code 71-079 stamped on them. I cannot see the second stamp on the volume pots because these numbers are hidden underneath the solder connecting the various wires.

What resistance are these pots? Is it reasonable to assume that the volume and tone pots have the same resistance because they are all marked R1378511? Or is it possible that the volume pots have some other different code concealed under that solder? Any additional information about these pots and their codes would be appreciated.

Note: It did occur me to just put a multimeter across the pots, but they are wired together with the pickups, and I don't know the DC resistance of the pickups.

EDIT: I did managed to find a bit more information about the 71-079 code. This article also suggests that there is meaning in the R code. I might be overreaching a bit, but the code on mine might indicate they were manufactured in the 11th week of 1985.

I also want to identify the type + specs and any other details folks might have about the capacitors. I'm no expert but they appear to be ceramic or mica capacitors and are marked mp 203m 100v.enter image description here

  • 1
    \$\begingroup\$ If you have a dental mirror or similar you can try looking at the sides of the pots -- you'll often find the values stamped there, if they're anywhere. \$\endgroup\$
    – TimWescott
    May 31, 2019 at 23:38
  • \$\begingroup\$ Gibson still sells replacement parts. the pices are high like $10 but i'd not call it extortion. \$\endgroup\$ Jun 1, 2019 at 4:06

1 Answer 1


Capacitors are ceramic disc type, 203M 100V meaning 20 × 10^3 = 20000 pF = 20 nF, M = 20 % tolerance, and 100 volts.

It seems you found it is a 100 Kohm pot. You can verify that by using a multimeter, measure resistance from two end pins, not from the middle one. The pot that is nearest your finger is easiest to measure, bottom pin is not connected and top pin is connected to case for grounding purposes. As middle pin connects only to a capacitor, it does not affect measurement result.

  • \$\begingroup\$ Very helpful! Any thoughts on the manufacturer? \$\endgroup\$
    – S. Imp
    May 31, 2019 at 23:04
  • \$\begingroup\$ No, the MP might not be the manufacturer but model series. Or some date code. \$\endgroup\$
    – Justme
    May 31, 2019 at 23:19
  • \$\begingroup\$ There's a really good chance that those are manufactured for Gibson, with Gibson part numbers. That means they could be manufactured by anybody (or possibly more than one "anybody"). \$\endgroup\$
    – TimWescott
    May 31, 2019 at 23:38

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