Agilent Technologies 856290216 service manual Assembly Test Points, Ribbon Cables, Pad, Test Jack

Assembly Test Points

The spectrum analyzer board assemblies contain four types of test points: post, pad, extended component lead, and test jack. Figure 7-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, 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 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 7-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 spectrum analyzer. The following five cables use different pin numbering methods on the jacks (signal names remain the same but the pin numbers vary):

WI, power cable

W2, control cable

W4, option cable

A3W1, interface cable

A19W1, HP-IB cable

Figure 7-2 illustrates the pin configurations of these five cables. Cables Wl 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, Jl(A)). Board assembly jacks connected to Wl will always be labeled Jl. Board assembly jacks connected to W2 will always be labeled J2.

7-2 General Troubleshooting