[time-nuts] Tektronix TM500 Series Help
Charles P. Steinmetz
charles_steinmetz at lavabit.com
Sun Jan 3 20:55:17 UTC 2010
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
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