[time-nuts] Tektronix TM500 Series Help
djl at montana.com
Sun Jan 3 21:28:37 UTC 2010
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.
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:
> Best regards,
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Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
Huson, MT, 59846
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