Chapter 6 283
General Troubleshooting
Introduction
diagrams and circuit boards. The name of the test point will be etched
into the circuit board next to the test point (for example, TP2). In some
instances, the test point will be identified on the board by its number
only.
Pad
Each pad test point uses a square pad and a round pad etched into the
board assembly. The square pad is the point being measured. The round
pad supplies a grounding point for the test probe.
Test Jack
The test jack is a collection of test points located on a 16-pin jack. There
are over 26 test jacks used throughout the spectrum analyzer. The HP
85629B Test and Adjustment Module uses the spectrum analyzer test
jacks during diagnostic and adjustment procedures. The pins on the
test jack may be manually probed, provided caution is used to prevent
accidental shorting between adjacent pins.
Figure 6-1 on page 284 illustrates the pin configuration for the test
jack. Line names are the same for all test jacks. The following
mnemonics are used: MS "measured signal," TA "test and adjustment
Module address line," and OS "output signal." Test jack test points are
identified on block diagrams by both the jack/pin number and line
name.
Ribbon Cables
Ribbon cables are used extensively in the spectrum analyzer. The
following five cables use different pin numbering methods on the jacks
(signal names remain the same but the pin numbers vary):
W1, Power Cable
W2, Control Cable
W4, Option Cable
A3W1, Interface Cable
A19W1, HPIB Cable
Figure 6-2 on page 285 and Figure 6-3 on page 286 illustrate the pin
configurations of these five cables. Cables W1 and W2 use two pin
numbering methods on their many jacks. These methods are identified
in the interconnect and block diagrams by the letters "A" and "B" next
to the jack designator (for example, J1(A)). Board assembly jacks
connected to W1 will always be labeled J1. Board assembly jacks
connected to W2 will always be labeled J2.
Figure 6-4 on page 287 shows the pin configuration for the 80 pin, W60
cable that is found on EC-series instruments. The numbering of the
pins is identical at J8 on the A2 Controller board and at J1 on the A17
Display Driver board.
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