Agilent Technologies 85024A, User'S And Service Manual

Page: 50 / 66

7-4 Chapter 7
Service
Troubleshooting Procedures
Troubleshooting Procedures
CAUTION The probe contains an input GaAs amplifier microcircuit that is highly sensitive to
electrostatic discharge (ESD).
When repairing this probe, you must use an anti-static
wrist strap, and work at a station equipped with an anti-static surface! Before you take a
measurement with a digital multimeter, discharge the leads by touching them to ground.
Mechanical Failure of the Protective Sleeve
The probe wand/cable must be replaced if the protective sleeve fails to slide and lock properly.
Electrical Failure of the Probe
Visually Inspect the Probe Tip
Inspect the probe tip for damage. If it is bent or broken, replace it by referring to “Replacing the Probe
Tip” on page 7-8 . Perform the “Operator’s Check” on page 4-4 . If the problem persists, perform the
following procedure.
Power Supply Check
Refer to the probe schematic in Figure 7-2 on page 7-5 when performing the following procedure.
1. Check the probe power output from the supplying instrument or power supply. The output pins and
voltages are shown in Figure 7-4 on page 7-6 . Check continuity of the ground pin to chassis ground;
it should be less than 1

.
• If the supplies are within the tolerances given in “Power Requirements” on page 3-3 continue to
step 2.
• If the voltage is not present at the supplying device, or the ground pin is open, troubleshoot as
required. Suspect a broken wire going to the probe power jack.
2. Follow the procedure in “Replacing the Amplifier Microcircuit” on page 7-9, to remove the probe’s
nose assembly, amplifier microcircuit, elastic conductive strip, and spring clip. These items are
illustrated in
Figure 7-3 on page 7-5 .