Big Trak Versions, Serial Numbers, and Research

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The Big Trak was a big hit for its time, selling over two million toys. Like any other mass-produced product, it went through changes based on component availability and cost efficiency improvements. Although I don’t have access to the manufacturer’s archives, I have been able to piece together some information.

Board Revisions

Revision information is on the back of the Big Trak printed circuit board. Thus far, I’ve seen REV C, REV D, and REV E. Apparently the European version of the Big Trak has a REV L board!

Two changes between the REV C and REV D boards are the patterns around the screw holes and the location of a jumper wire hole (see arrow).

Two changes between the REV C and REV D boards are the patterns around the screw holes and the location of a jumper wire hole (see arrow).

The REV D board includes dot patterns around the screw holes. This may have helped hold the screws in place against vibrations. Or, the patterns may have reduced over-tightening or provided stress relief to prevent board cracking.

Additionally, one jumper wire hole changed from REV C to REV D. This may have been to reduce the length of the jumper wire or to make it consistent with the length of some other jumper wires on the board.

By moving a hole, physically smaller capacitors or shorter lead lengths could be used on the REV E board. (REV E photos courtesy of Pablo Bleyer Kocik)

By moving a hole, physically smaller capacitors or shorter lead lengths could be used on the REV E board. (REV E photos courtesy of Pablo Bleyer Kocik)

Another hole changed from REV D to REV E. This permitted the length of the leads on capacitor C9 to be greatly reduced, improving the effectiveness of the capacitor in decoupling/bypass. Also, it’s a lot easier to insert the capacitor straight into the holes, rather than bending the leads to exactly the correct length.

The REV C and REV D boards I’ve seen have green solder masks. The REV E boards I’ve seen have a red solder mask.

How Many Big Traks Were There?

The Big Traks I know about have the following information:

Serial NumberPCB RevTMS Date 75494 DateSpeaker Motor TransistorsNotes
1007748*C792379198 ohmTO-92Has U1, R1, R2, jumper traces, plug wire stub
1129128*D793279198 ohmTO-92Has R1, R2, jumper traces
1180691*C793679198 ohmTO-92Has R1, R2, jumper traces, plug wire stub
1238030D79367936No IN circuitry.
1411838*D8001792732 ohmTO-92No IN circuitry.
1438262D7936792332 ohmTO-92No IN circuitry. Sticker with battery.
1706580D80058001No IN circuitry.
1755076*E8014791932 ohm2N6715No IN circuitry or key hole. Sticker underneath. Missing 4 screws.
1791200D80148018No IN circuitry.
1806157*E8018801832 ohmTO-237No IN circuitry. Missing cardboard and 4 screws.
2045315*E8014803532 ohmTO-92No IN circuitry. Missing cardboard and 4 screws.
*Currently own. Big Trak silver-colored serial number sticker. The first '1' digit (see arrow) appears to be pre-printed.

Big Trak silver-colored serial number sticker. The first '1' digit (see arrow) appears to be pre-printed.

The serial number appears on a silver sticker located in the 9 V battery compartment (earlier models) or underneath on the gearbox (later models).

The first digit (1 million) appears to be preprinted on the sticker. Either they were trying to make it look like they were shipping a lot of Big Trak toys (likely), or they had already made a million in the middle of 1979 (unlikely). Sometime in 1980 or later, they either had made at least a million more Big Traks (likely), or they were incrementing the serial number in funny ways.

Recently, I was fortunate enough to obtain a Big Trak with a serial number in the 2 million range. I suspect these are much rarer, comprising as few as 5% of the total Big Traks produced. This Big Trak has four unthreaded screw holes and a few other distinguishing characteristics. This makes it harder to falsify than simply attaching a fake serial number sticker to an earlier Big Trak. (I have chosen not to post a picture of the 2 million serial number sticker to avoid fakes.)

Resources

Big Trak instruction manual: http://www.hasbro.com/common/instruct/BigTrak.PDF

Big Trak Transport instruction manual: http://www.hasbro.com/common/instruct/BigTrakTransport.PDF

I would appreciate any source information (I already have the original manuals and boxes), like photocopies of original technical articles, magazine articles, books, or even the names/contact information of the engineers. I’ve been told the following material exists. Could you see if you have a copy?

Robot Room readers have allowed me to see the following source material:

Robotics Age, Volume 2, Number 1, Spring 1980, pp. 38-39. (Thank you Rick Rowland)
Confirms $40 retail price. Cites Mel Taft as Milton Bradley’s Senior Vice President of R&D. Reiterates that manufacturer plans to produce accessories in addition to the trailer. Confirms manufacturer intended to produce a million Big Traks. Indicates future Big Traks would include voice synthesis. States that manufacturer licenses about half the devices inside toys.
Toy Robots Gaining Intelligence. Byte, vol. 5, October 1980, p. 186. (Thank you David Ellis)
Confirms over 1 million made. Confirms 1K ROM.