Dating Guitars – Pot Codes

by Rik Mercaldi on July 20, 2012

Pot from a 1979 Les Paul Custom

Pot from Les Paul Custom manufactured by CTS in 30th week of 1978

We’re not talking about dinner and a movie, of course… For my first blog post on dating instruments, I’d thought I’d talk about potentiometer or, “Pot” codes which can be used to help date almost all electric instruments, amplifiers, and effects pedals made in the U.S, as well as many in Europe, etc. The Pots are the small parts responsible for the volume and tone controls.  This should never be the only method used, but quite often it can help back up evidence already acquired to date an instrument.

The method of dating is actually pretty simple. First you need to get underneath, to the circular disc on the bottom of the shaft at the opposite end of the knob (which may, or may not, have to be removed depending on the instrument). In most cases if it’s not made unreadable by blobs of solder, you should see a six or seven digit number. The first three digits represent the manufacturer, the next one or two represent the year, and the last two will be the week it was made. Six digits were changed to seven starting in the 1960’s making the year two digits instead of only one. This means that if you don’t have a basic ballpark of the period an instrument was made prior to the 1960’s then Pot codes won’t really help you.

For example, the Pot codes you can make out are: 1377415. This means that the Pot was manufactured by CTS company in the 15th week of 1974.  If your earlier detective work determined that the guitar was probably made in the early 70’s, you can now ascertain that since you always date an instrument by the latest dated part, that it’s most likely from 1974. Let’s say that you’ve dated a particular Gibson Les Paul Deluxe to be from 1972, and the pot code says 1378912. If all of your other evidence is pointing to 1972 then the guitar has had the pots changed. If you’re concerned with an instrument being an “all original” vintage collectible, the number of changed parts can greatly affect it’s value. Once you see one replaced part, there could be more, so keep looking…

Again, that’s why Pot codes should always be used to reinforce the date of the guitar and not be the sole source. Parts are often replaced and there are signs to look for which we’ll get more into in a later post.

  • BobbyV

    Useful article. Another thing to look for is the solder on the pots. It should be slightly oxidized and yellowing if it’s original.

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