[time-nuts] Tektronix TM500 Series Help

[Don Latham]

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
>
>
>
>
>
>
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-- 
Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
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VOX 406-626-4304
www.lightningforensics.com
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