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Troubleshooting
This chapter provides troubleshooting information on the HP 70001A mainframe. Problem
isolation and diagnosis related to the front-panel fault indicator lights, fan operation, fuse
replacement, and power-on light are discussed as operator-level repairs.
Turn On
When the HP 70001A as part of an HP 70000 Modular Measurement System is turned on, the
mainframe monitors its condition as it brings power and cooling air up to speci cation. Once
power and cooling is established, the modules begin their self-test sequences.
The power ON light should come on and stay on.
The VOLT/TEMP and I/O fault indicators should blink on and then turn o .
The CURRENT fault indicator should not light.
The fan noise will be noticeable.
During this self-test, the module ACT and ERR lights of all the modules in the instrument
will be turning on and o . After about a minute these lights should settle down to a steady
state.
After the module self-test is complete, the power ON indicator is the only mainframe light
that should remain on.
Note
Some older models may have a fourth fault-indicator labeled AIR FLOW. This
indicator should not light. The circuitry for this function should be disabled.
Line Fuse
A 6.3 A, 250 V line fuse is located inside the power receptacle on the back of the instrument.
The most common reason for an open fuse is improper setting of the line voltage selector,
however, internal problems can also cause a fuse to open.
See Figure 2-2 for fuse removal and replacement information. Refer to the HP 70001A Service
Manual for troubleshooting information.
5
Troubleshooting 5-1
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