Agilent Technologies 8564EC, Service Manual

Page: 236 / 512

Chapter 7 317
General Troubleshooting
Introduction
Assembly Test Points
The spectrum analyzer board assemblies contain four types of test
points: post, pad, extended component lead, and test jack.
Figure 7-1 on
page 318 illustrates each type of test point as seen on both block
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 approximately 20 test jacks used throughout the spectrum analyzer.
The pins on the test jack may be manually probed, provided caution is
used to prevent accidental shorting between adjacent pins.
Figure 7-1 on page 318 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) 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 cables use different pin numbering methods on the jacks
(signal names remain the same but the pin numbers vary):
W2, control cable
W4, option cable
A3W1, interface cable
A19W1, GPIB cable
Figure 7-2 on page 319 and Figure 7-3 on page 320 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.