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Part of the schooling for junior engineers at Tek was strong encouragement to use the Common Design Parts Catalogs. I think I was told it cost $10000 of overhead to add a new part, so if you asked for one, you'd better be ready to prove that nothing there would do.

Dave Wise
Information Display Division, 1980-1995
________________________________________
From: [email protected] <[email protected]> on behalf of Brad Thompson via groups.io <brad.thompsonaa1ip@...>
Sent: Saturday, May 02, 2020 4:25 PM
To: [email protected]
Subject: Re: [TekScopes] Question re: capacitor in Tek 181

Ernesto wrote on 5/2/2020 3:35 PM:

Hi Brad,

Another question is why C401, which has identical description as C430 and C431, (2x20uF, 450V, -10%, +50%), has a different part number.

Hello, Ernesto--

C401A and C401B are listed as 2X20 uF, p/n 290-036.
C430 is listed as (2X20 uF), p/n 290-037
C431A and C431B are listed as 2x 20 uF, p/n 290-037

In the schematic, C430 appears as a single 40 uF capacitor-- it's
connected in parallel with C431A 20 uF.
Showing C430 as C430A and C430B (20 uF each) connected in parallel would
clarify matters.

As for C401 and C431 having two different part numbers, perhaps C431
gets prepped with an insulating
cover (since its can floats at -150 volts with respect to the chassis)
and hence deserves its own part number?

Maybe the Tek engineer was also a unique artist, like Leonardo Da Vinci, and wanted other engineers to stand in admiration in front of his designs asking themselves questions, like the public standing in front of the Mona Lisa ask themselves "why is she smiling?".

From an engineering viewpoint, The "Mona Lisa" could have been painted
on a smaller canvas for
more efficient use of materials.<g> (Ear protection in place to muffle
outraged howls emanating
from artaficionados).

My personal take on this is that if we wonder why some piece of equipment seems over designed or under designed, or over specified or under specified, we should not assume that there was some esoteric reason in the superior mind of the designer, but take it as some mundane oversight. And we are free to follow that detail or not. (stated by a former designer).

Or as someone suggested, perhaps there were leftover 6.25 uF caps in
stock. Never underestimate
a buyer or purchasing agent's appetite for shortcuts.

I served as components engineer for a small (soon to be even smaller)
<snip>