HP C2858A, Service Manual

Page: 154 / 198

9-3
Product History
HISTORY OF PRINTED-CIRCUIT ASSEMBLIES
Hewlett-Packard’s PCAs have three major identification features:
Part Number. PCAs having the same part number are directly interchangeable.
If a PCA is revised in any way that makes it non-interchangeable with
previously issued PCAs of a particular part number, a new part number is
assigned to the revised PCA.
Revision Letter. This letter identifies the most recent revision to the etched
circuit pattern. The original issue is identified with the letter A. If the master art
work for a printed circuit board is revised in order to alter performance or
manufacture, the revision letter is changed to the next letter in the alphabetical
sequence.
Assembly Date Code. The date code on the PCA is a four-digit number which
identifies the assembly level by date code. The PCA date code is changed when
a component or component part number is changed which alters the
performance of the PCA. The first two digits represent the last two digits of the
current year and are derived by subtracting 60 from the current year; the last
two digits represent the week in that year, ie: 3302 = second week in 1993. Any
digits following a hyphen in the date code represent the division that
manufactured the printed circuit assembly.
Table 9-3 is a quick-reference table that lists PCAs by part number and date code. Listed next
to the part number and date code of the PCAs are the Items located in this chapter that de-
scribe the differences between the PCA in question and the level of that PCA described in the
main body of this manual.
Table 9-3. PCA Reference by Date Code
PCA Date Code Items
NO CHANGES