Dating your Magnavox Odyssey by David Winter

    Many collectors have been trying to decipher the Odyssey serial numbers to determine their date of manufacture and their real position in the whole production run. Unfortunately, the internal Magnavox documents containing this information have been permanently lost and I could see all sort of mistakes on the web, ranging from Odyssey units said to be from 1972 when they were from 1975, to supposedly early serials which, although lower than others, corresponded to later specimens, etc.

A lucky start point...

    However, my Magnavox archives contain a folder called Horizontal Drift which details some humidity tests performed on a number of units. Two tables list the various units tested along with their serials and precise date of manufacture: one with the units made between late October 1972 and early December 1972 (model 1TL200BLAK RUN 1; the first production run), and the other with specimens made in October and November 1973 (model 1TL200BLAK RUN 2; the second production run). From these tables I could easily estimate any unit made during these periods of time. However, around half of the whole Odyssey production was made outside of these time frames and could not be dated. Finding that information was my next big challenge and I was extremely sceptical about being successfull.

An unexpected find put me on the right way...

What really motivated me was something I would have never expected to find while browsing my files: an exceptional page containing the following handwritten codes:

    W = Aug
    O = Sept
    R = Oct
    K = Nov
    M = Dec

    2M15 = Dec 15 '72

    At a first glance I didn't realize what this meant, but shortly after an image flashed through my mind: the large red code printed on all Magnavox Instrument Inspection cards like those shown below. After a rapid check of my inspection cards and by comparing with the Odyssey serials dated on the humidity tests pages, I got the confirmation that the precise date of manufacture of each Odyssey was encrypted in the large code on the bottom of its Instrument Inspection card. The problem was that I only had the letters corresponding to the last five months of the year and the rest remained a mystery. At least for now.

The answer: several years of patient study...

    Clearly, there was only one way to find the missing letters, and this would take me several years of patient research: checking Odyssey sales every day to see their Inspection Cards in order to build a database and hopefully determine the missing letters. By putting the serials of a same year in increasing order, and despite what I call “crossed batch serials” (see below), the following acronym began to surface again after 35 years: QUALITYWORKM. As a matter of fact, Magnavox products' quality was a real reputation. The meaning of the last letter is still unknown (probably the company). From that, I was able to date not just every Odyssey 1TL200 produced, but also all Odyssey 100, 200, 300 and 400 units made until the fall of 1976 when Magnavox changed the type of serials and abandoned the old punched Inspection Cards.

Here is how you can decipher the large code on the Inspection Card:

  • The first three digits remain a mystery.
  • The fourth digit determines the year: 2 for 1972, 3 for 1973, etc., until 6 for 1976.
  • The letter determines the month using the QUALITYWORKM acronym, where Q stands for January, U stands or February, and so on until M, which stands for December.
  • The next two digits determine the day of the month.
  • The next digit and the last letter are a mystery, although the digit is always 1 and the letter anything between A and J.

If you don't want to decode manually your cards, you may use my decoder below:

Full code (9 characters):     Decoded date:

Crossed serial batches: avoiding mistakes...

    From the above information, the 2W07 code of the Inspection Card below refers to an Odyssey completed on August 07th, 1972, which is early in the production. One who does not have his Inspection Card may easily consider that a similar serial starting with 70 also corresponds to an early specimen. Quite in the contrary, other serials starting with 70 happen to date from late August. A good example is the second Instrument Inspection Card below which serial starts with 69 but corresponds to a specimen completed on August 28, 1972 ! Therefore, please do not consider that a serial indicates how early an Odyssey is. Only the date found on the Instrument Inspection Card is relevant.

Left: an early specimen (7 August 1972). Right: a later one (28 August 1972), although with a lower serial.

Left: a Shooting Gallery Rifle completed on 19 February 1975. Right: an Odyssey completed on 25 April 1975.

Another approximate solution...

    If your Odyssey no longer has its Instrument Inspection Card, there is still one way to roughly estimate when the unit itself was made. For that, please be curious and do not fear opening your Odyssey console ! For that, remove the two black knobs near the controllers plugs, and remove the four screws on the bottom. Next, all you need to do is check some date codes on some electronic components inside your Odyssey:

    - The potentiometers contain a 4-digit date code: the first two digit is the year and the other two the week of the year.
    - Some capacitors may also contain the same type of 4-digit date code.
    - Most transistors also contain a 3-digit date code just above their legs: the first digit stands for the year and the other two for the week.

And to finish...

    The Final Performance code (four digits) is still a mystery. So far as I know, its first two digits are almost always same as those of the day and the remaining two represent something still unknown. Although they equal 72 on the above card, they do not represent a year. Amazingly, inspection cards for Shooting Gallery rifles seem to use a different encoding for these four digits. They often equal 0369 but a few same codes have been found in the early production: 9260 and 4637.

    The last thing I should mention is misprints. Having seen a number of incorrect date codes, I thought it would be interesting to show a few of these cards from which the date is impossible to determine without a relevant database. One misprint seems to have concerned several Shooting Gallery rifles (serials starting with 728 although 7281203 is correctly dated). Such cards miss the first digit of the day, making it almost impossible to precisely date them, mainly because several serials batches were crossed.

Left: misprinted letter L intead of M (the date cannot be April 1, 1972 as all rifle serials close to this one date from December 1972).
Right: another rare misprint with incorrect 7TL950 R1FL model, and missing first digit of the day (November, 1972).

Another rare misprint: year cannot be 1978. It is either 1973 or 1974.