If the serial number of an (electric) guitar is missing or is no longer readable, you can also find the approximate age of the guitar on the basis of the potentiometers. On the potentiometer is a code that gives information about the manufacturer and the year and week when it is made.

Where to find the code
Stamped or punched you can see a six- or seven-digit source code on the back or side of the potentiometer.
Sometimes there is a space or dash between the manufacturer code and the year/week code.

With the potentiometer decoder you can decipher when and by which
manufacturer it was made.

  Potentiometer decoder

The potentiometers (pots) on the guitar offer a oppotunity to find the production date by a source code. Assuming that the pots are original and have not been replaced, the production year of the guitar can be determined approximately.

The source code on pots indicates the manufacturer and date when they are made.
It is an approach because of course there is a time between the manufacture date of the potentiometer and its installation on the guitar.

This is also a method for lesser known brands without a serial number about the production date.

Read source code
With help of the EIA (Electronics Industry Association) number on the potmeter, the production date can be determined.
The first 3 digits on a pot are the manufacturer code.
The last 3 or 4 digits are the date code.
With 3 digits, the first digit is the last digit of the year, and the last digit is the week number.
With 4 digits, the first 2 digits are the last 2 digits of the year.

IRC (International Resistive Company) used a different date code system.

In the 1950s, Fender mainly used potentiometers from the Stackpole brand. From 1963, the switch was made to the CTS brand. To save costs, a huge stock of CTS was bought in 1966 that was installed on the guitars until 1971. Guitars made until 1971 can therefore have potentiometers with the datacode of 1966. To save costs, a huge stock of CTS was bought in 1966

The suppliers of pots at Gibson are (were) IRC,
CGE (with the Gibson logo), CTS and CentralLab.
IRC and CGE were used in the 1950s.
Due to a fragile construction of the CGE potmeters (show rapid wear over time), Gibson has therefore switched to pots from CTS and later on CentralLab.

Höfner guitars from before 1971 often do not have a serial number. You can read on the bottom of the pots of these guitars 128KΩ or 250KΩ with a 3-digit number. Here too, the first digit is the last digit of the year and the second and third digit the week.

Potentiometer 1963, week 39