Publication 21555, Rev. E, September 2002 5-1
5
Maintenance
5.1 Introduction
This chapter defines maintenance practices and calibration and troubleshooting checks that assist in
fault isolation. Problems can occur that might be produced by peripheral equipment or components.
Preliminary checks should be made to ensure that peripheral equipment or components are not causing
what appears to be a malfunction within the power meter.
The maintenance and calibration procedures in this chapter should be performed at least once each year
unless the power meter is operated in an extremely dirty or chemically contaminated environment, or is
subject to severe abuse (such as being dropped). In such cases, more frequent maintenance (immediate,
if the unit is dropped or severely abused in some way) is required. The unit’s front panel and housing can
be cleaned using a cloth dampened in a mild detergent. Do not use abrasive cleaners, scouring powders,
or any harsh chemicals. Wipe the soap residue off with a clean, damp cloth, then dry with a clean dry
cloth.
Make a performance verification check in accordance with the procedures given in Section 4.4 of this
publication. If the unit will pass all of the performance tests, there is no need for calibration.
5.2 Power Supply Voltage Checks
There are six power supplies. They are all located on the A1 Analog PC board. In case there is a
regulated voltage failure, check the corresponding unregulated supply with reference to schematic
diagram 21360 on page 7-6. The unregulated voltage must be at least 2volts more than the required
regulated output. To measure the supplies, turn the unit on and let it stabilize for a minute or so. Then
proceed as follows:
1. Connect the DVM from A1TP3 (ground) to A1TP2 (+) on the Analog assembly. Measure
+14.25V to +15.75V.
2. Connect the high side of the DVM to A1TP4. Measure -14.25V to -15.75V.
3. Connect the high side of the DVM to A1TP5. Measure +4.75V to +5.25V.
4. Connect the high side of the DVM to A1TP9. Measure +11.4V to +12.6V.
5. Connect the high side of the DVM to A1TP10. Measure -11.4V to -12.6V.
6. Connect the high side of the DVM to A1U14, pin 1. Measure -9.1V to -10.9V.
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