These external transistors are shown on the PS503 as single transistors, and they are driven by a single stage transistor from an op amp.The external pass transistors for each plug-in could use NTE182 (NPN) and NTE183(PNP). IMHO, the hfe of the NTE devices will be entirely adequate, and they're cheap as well. I think I used one of these to repair a 500 series p/s in the past. It's worth a try. Don
Charles P. Steinmetz > Mark wrote: > >>The mainframe power transistors are NOT darlingtons. They are plain >>NPN/PNP power transistors with non-standard pinouts. > > The TO-127 pinout is ECB -- most other plastic power transistor > packages are BCE. > > I just pulled the cover off a TM503, and the 151-0349-00 (and > 151-0373-00) devices in it are NOT darlingtons. > > At least some Tek manuals say the 151-0349-00 devices are SJE924s, > and the information I have on those (which I copied from a now long > lost Motorola databook of the era) indicates that they are > darlingtons (there is some corroboration for this on the web, but I > have not found a web datasheet). However, a current source of Tek > parts (see below) says that its 151-0349-00 devices are MJE2801s, > which I believe are not darlingtons. So, either Tek was incorrect in > stating that P/N 151-0349-00 = SJE924, or the Motorola datasheet I > copied from was wrong that SJE924s are darlingtons, or I copied > wrong. (Surely it couldn't be the third? ;-) In any case, it > does not appear that the transistors in TM5xx frames are darlingtons. > > If anyone wants original form factor TO-127 transistors (presumably > Tek old stock, marked "034900"), they are available from: > > http://www.sphere.bc.ca/test/tek-parts/tekparts2.html > > Best regards, > > Charles > > > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
