HP 8560A, Service Manual

Page: 207 / 450

Assembly Test Points
The analyzer’s board assemblies contain four types of test points: post, pad, extended
component lead, and test jack. Figure 6-l 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,
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 analyzer. The HP 85629B Test and Adjustment Module uses the
analyzer’s 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-l 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 analyzer. The following five cables use different pin
numbering methods on the jacks (signal names remain the same but the pin numbers vary):
Power Cable
W2, Control Cable
W4, Option Cable
Interface Cable
HPIB Cable
Figure 6-2 illustrates the pin configurations of these five cables. Cables 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,
Board assembly jacks connected to will always be labeled Board assembly
jacks connected to W2 will always be labeled J2.
8-2 General Troubleshooting