When semiconductors first appeared in consumer electronic products, each equipment manufacturer had the choice to either use transistor-factory's catalog numbered parts or to have their own "house" number printed on them. The manufacturers of all those parts would build a (say) diode optimized for some particular task, like turning RF into receiver audio, or rectifying the B+ supply. It was an explosive-growth market that spawned a slew of providers, each competing for the same market, factories building electronic gadgets. In other words, there would be maybe) ten different manufacturers' transistor of a given type, each one slightly different but meant to do the same job. There was some effort to standardize part numbering the way they did with vacuum tubes in the 1940s. A 6J6 tube from any of six factories should behave the same way. Various semiconductor brands put together the JEDEC, or Joint Electron Device Engineering Council. This led to the "1N.., 2N.. etc part-numbering scheme for parts made in the USA. Never mind Japan. They did their own thing.
This proliferation of parts that could interchange was a dilemma for a service company. If you only serviced one brand of TV, you could just get your parts from the factory's support division.
On a good day. And if you wanted to offer service on a dozen brands of TV, this became an inventory nightmare. Savvy entrepreneurs figured out that if you knew each manufacturer's part number for a NPN power transistor that's good up to 60 Volts, can take 3 Amps collector current, has a bandwidth limit of 1 MHz and a gain of 50, you could substitute any one of ten different brand parts that all meet or exceed that spec. Substitution books appeared, and then the practice of erasing the original number and printing your own took over. More money to be made selling parts than books, it seemed. There's another angle to this. Many transistors were sold with almost-same frequency and gain, but at a range of breakdown voltages. Texas Instruments sold a line of plastic power transistors that came rated for the same current, wattage and gain, but rated for 40 Volts, 60, 80 and 100. The TIP31 with no suffix letter was the lowest-voltage part, and the TIP31C was the 100-Volt type, the suffix letters A and B the two steps between 40 and 100 Volt rating. Never mind why, but the "C" version of the part is a proper substitute for the lower-rated numbers. What this meant for the service outfit was he could stock one part that served to replace a speaker-amplifier transistor that worked in ten brands of amplifier, not just one. Like any explosive-growth market a slew of brands would offer "universal" parts. Each brand had a cross-reference book thick as a phone directory. By the 1980s it was narrowed down from dozens of names on 'universal' parts down to Motorola, RCA, GE and Sylvania. No accident these names had previously dominated the tube market. Each had a letter prefix ahead of their part numbers. RCA called theirs "SK". GE sold a line of sub parts prefixed with "GE". Original. Motorola called theirs "HEP", meant to signify "Hobbyist, Experimenter and Professional" products. Sylvania numbered theirs "ECG" for Electronics Component Group. There were some small-time outfits left doing this, but they disappeared first. Prices for consumer electronics had a steady downward trend, reducing the demand for repair parts. Pretty sure Motorola bowed out of the HEP business first, when sales growth sputtered. A renegade outfit in New Jersey called New Tone Electronics jumped on this bandwagon, but cut their expenses by using Sylvania's numbers but with the prefix letters "TCG", as in Technicians' Components Group. No need to research and print that phone-book size cross reference. Just look it up in the Sylvania book. They did give it away, after all. Sylvania sued them and won. The settlement required them to change the New Tone product's prefix letters. They chose "NTE" for New Tone Electronics. One by one all the competitors in this trade fell by the wayside. Left NTE the last man standing. The upstart outfit riding the coattails of big, bad Sylvania outlasted them all.
But nothing lasts forever.
RIP NTE
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