Determining the year of manufacture for your vintage guitar is very important. It’s one of the most fun parts of vintage guitars but it can also be the most frustrating. Fender used at least four different serializing schemes from 1950 to 1980. Gibson used countless schemes and also reused numbers at least three times within the span of 20 years! The best way to assign a year of manufacture to a guitar is to date each part individually then see how the guitar as a whole lines up to established dates. The potentiometers, or variable resistors that are turned to vary the volume or tone, have codes on the back that indicate the week and year they were manufactured.
Let’s look at the control cavity of this 1967 Gibson Melody Maker D. Here we can see the braided leads coming from the pickups, an output jack, two orange ceramic disk capacitors, and four round metallic things with codes on the back. The round metallic things are called potentiometers. On this guitar, the top two are volume and tone for the neck pickup and the bottom two are volume and tone for the bridge pickup.
There are a few sets of codes on the back of potentiometers. Look at the one with the least amount of solder on the back, bottom right. The “CBA-811-1053” isn’t helpful for our dating purposes. Next is “500k” which is the max resistance of the potentiometer, also not useful for dating. The code we are looking for starts with 137. 137 is the manufacturer code, in this case indicating CTS or Chicago Telephone Supply. The next part of the code will have three or four digits. The three digit codes will have one digit for the last number of the year and two digits for the week of the year. The four digit codes will have two digits for the last two numbers of the year and two digits for the week of the year.
One problem with potentiometer date codes is that they are often covered up with solder! Sometimes you have to piece together the code from multiple potentiometers. The bottom right pot has the numbers “1376xxx” visible. The pot above that one seems to indicate “13767xx” indicating 1967. That’s all I can make out from these potentiometers so let’s try another.
Much better! Here we have the control cavity of a 1965 Fender Jazz Bass. It has its original CTS potentiometers with the codes on the side of the pot. There is no pesky solder in the way so we can easily decipher this code. “1376542” reads 137 (CTS brand), 65 (1965) and 42 (42nd week of the year).
It’s interesting that the potentiometer code on this bass guitar indicates the 42nd week of 1965 but the neck stamp is April of 1965. Necks were stamped very early in the manufacturing process at the Fender plant at the time. It’s common to find neck dates and serial numbers off by about that much time. If the dates are off by a year or more then it’s possible that the neck and the body didn’t come together. It’s also possible that the part was replaced.
It’s very common to find potentiometers and other electronics replaced on a vintage guitar. Many players didn’t care about having an original vintage guitar so they didn’t mind ripping out the old electronics and putting in new ones. Potentiometer codes are only helpful if they are original to the guitar.
Can you decipher these codes?
Leave a comment with the date code!