Dating Your Toshiba
by Robert Davidson, transistors@abetterpage.com
No, I’m not suggesting you take your favorite Toshiba radio out for a night on the town – if you do, well, that’s your own business. During the 1980s and ’90s, when transistor radios were first becoming collectible, there were very few ways to establish production and distribution dates for any particular transistor radio, whether manufactured in the US or Japan or in Europe. The Howard W Sams Transistor Service Manual series was helpful here but unreliable overall, and magazine advertisements were useful in approximating distribution dates, but not production dates. A fair number of transistor radios had production date tags glued to the speaker magnet or on the inside face of the back cabinet cover, and sometimes the discrete components themselves (transistors, resistors, capacitors, tuning capacitors) offered up clues.
But all these hints still left a majority of transistor radios, sadly, “undatable.” When I first put up a transistor radio web site in the mid-’90s, I devoted a full section of it to Toshiba transistors: the cabinet designs were just so audaciously original – from the “Bathroom Scale” 6TP-31, to the “Concentric Ring” 8TP-90 and the “Coffin” 6TP-304 – they really deserved their own page. But when were these made? I knew roughly, approximately, but not exactly…
Then in early 1997 a "hunch" was proposed by collector Fred Mason in an email to me: The hunch was that Toshiba placed production dates within its serial numbers – but since Fred only had three Toshiba transistor models, he really couldn’t say for sure. I sent him a list of serial numbers for 29 Toshiba models in my collection, along with my own guess of what the coding scheme was -- and for him (and for me), this confirmed the hunch.
Here’s the serial number coding scheme:
1. The first digit is the final digit of the year of manufacture,
2. The second and third digits indicate the month of that year,
3. The five remaining digits are the "core" serial number.
For example: a "Concentric Ring" 8TP-90 has the serial number 00800512... this would mean that it was unit number 512 produced in August, 1960.
Go grab your vintage Toshibas, look at their serial numbers, and you’ll note that:
a. For each set the first digit is either 9, 0, 1, or 2 -- as in 1959, 1960, 1961, 1962 (and 3’s & 4’s of course would refer to ’63 & ’64 sets).
b. The second digit is exclusively 0 or 1, and if it is 1, then the third digit is without exception 0, 1 or 2. Get it? That’s how a 12 month calendar would display in two digits...
And while this serial number scheme gives a precise production date, it does not give a distribution date: like most major transistor radio manufacturers, Toshiba brought out most of its new models each year at the end of the year, just in time for the Christmas season – serial numbers indicating an October or November or December production date for a particular year would very likely belong to models labeled in advertisements as having been “made” (distributed) in the following year...
And Toshiba was not the only transistor radio maker to do this sort of thing. The US manufacturer Arvin placed production dates not in the radios’ serial numbers but in their model numbers: the Arvin 60R23 was produced in 1960, the 61R13 was produced in 1961, and so on – not as precise as Toshiba’s month-and-year serial number designation, but certainly easier to discern.
Editor’s Note: Robert Davidson is the person behind the huge, colorful and just-plain-fascinating web site, The M31 Galaxy of Transistor Radios. The graphics alone will hold you captive for an unconscionably long time. Check it out.
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