Jim Adney wrote:
If I'm that tech, how do I correlate that p/n with this cap on the
schematic? Does the schematic have both the value AND the p/n on it?
I understand your point about using the exact replacement, but I don't
see why a part should not have BOTH sets of data. To me, that seems
like it adds a lot of value to the part.
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Jim Adney
Madison, WI 53711 USA
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Typically, the schematic will identify the part by "circuit number", say
C143 (and might or might not show the value), and it'll be on page A4B3,
which is the schematic for board B3 in larger assembly A4. In the same
manual, there'll be a parts list for A4B3, where you can find the
description of C143, along with its part number. It would certainly
include the value, type, and probably the tolerance, which are important
to know when troubleshooting. Sometimes it'll tell a little more, if
there's something particularly unusual about the part. But the full
description of that part #20035942 only appears on a document that's
typically many pages long and fully describes its specifications. There
might be 100 different part numbers for 4.7 uF, 10%, 50 volt tantalum
capacitors, each with different specifications for reliability testing,
temperature range, ESR, mechanical lead strength, vibration tolerance,
tada, tada, tada. They are *NOT* interchangeable in the military or
commercial environment. Substitution could result in failure at a
critical time or place with incredibly expensive, disastrous, or fatal
consequences.
When replacing the part, the only thing that's important to the
technician is whether the replacement has the right part number. If it
doesn't, the part doesn't go in, regardless of what its capacitance
value might be.
Yep, stamping the value on the capacitor would undoubtedly add value to
the part for you and me. But again, the military just wasn't thinking of
us when it set up its stock system.
Roy Lewallen, W7EL