Posted on March 27 2020
Did you know that the parts inside your vintage electric guitar will likely have manufacturing date codes? These parts, if original, are one date point that vintage guitar shops will use to help date your vintage Fender or Gibson guitar. The year of manufacture of a vintage Fender or Gibson electric guitar is a significant determining factor in its value. Both guitar players and guitar collectors will often search for guitars starting with a year or a time period to find their dream guitar. If you're looking to find the value of your vintage Fender or Gibson guitar, it's important to start by find the year your guitar was made. Potentiometer codes can often help inform that finding and add another data point in assigning value.
Other helpful links:
How to date a vintage Gibson Les Paul
The easiest way to date pedals is the same way you date some guitars and amps - by the POT CODES. EH, MXR, and most US made effects used pots with EIA date codes on them. They usually start with 137 which is the manufacturer (137 = CTS), then the next digits are the year and week. For example, 137 7903 would be a CTS pot, made in the 3rd week. 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).
Dating vintage guitars can be fun but also 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.
Cts Pot Serial Number Search
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!
Around 1966 Fender started using CTS pots.
Look for this number: 035865
It’s a code for Stratocaster pots. Any vintage 66-76 strat pot must have 035865 stamped in the back. Simple. Some people on ebay are selling NOS pots claiming they are original Fender Strat pots but if they have a different (whatever) number then THEY ARE NOT STRATOCASTER POTS and they are not to be considered original parts. These NOS CTS pots are indeed as old as they claim to be and totally identical to the ones used by Fender, but have a different code, meaning they were destined to other (non Fender) instruments or electronic devices. BEWARE! I don’t normally indulge with capital letters but this time I did. Remember, 035865 is the deal.
There is a rumor that some 1968 strats were fitted with pots showing 032367, a code seen on Telecasters and P.Basses. I tend to believe this, I’ve seen some of these strats and the story seems legit to me in the end.
It also seems that pots were produced/ordered in mass during certain weeks only.
As istance, in 1971 I’ve only come across pots made in the 12th week. In 1970, I’ve only seen pots made in the 2th, 14th, 21th and 52th weeks.
250k= pot value
AUD=audio
137=CTS code
YY-WW (66=year, 18=week)
How To Identify Cts Pots
A strat pot with the Telecaster code (032367). I’ve seen this in a 68 strat for sale on ebay and took this pic.
Another 1968 strat I have seen for sale on ebay, showing the same code (please enlarge the pic, you should then see 032367 stamped in the tone pot)
Very late 1970 strat pot (52th week, the last one!). Notice also the anomaly with the straight plastic/fibre part, normally rounded. This happens only in the 52th week of 1970. Crazy stuff!
Late 1973 strat pot (035865 is the strat code). 137=CTS code 73=Year 50=Week