B&K Precision 1620A-1623A - Manual - Manual (Page 13)

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7. MAINTENANCE
WARNING: The following instructions are for use by qualified
personnel only. To avoid electrical shock, do not perform any
servicing other than those contained in the operating instructions
unless you are qualified to do so.
7.1 MAIN FUSE REPLACEMENT
If the main fuse blows, the power on the LED indicator will not light
and power supply will not operate. The fuse should not normally blow
unless a problem has developed in the unit. Try to determine and
correct the cause of the blown fuse, then replace only with a fuse of
correct rating. The fuse is located on the rear panel and fuse rating can
be found next to the fuse holder. If the problem persists, return the
unit to the agent for further investigation.
7.2 CALIBRATION
This unit has accurately calibrated at the factory before shipment. Re-
calibration is recommended only if repairs have been made in a circuit
affecting calibration accuracy, or if you have reason to believe the unit
is out of calibration.
However, calibrations should be attempted only if a 3½ digit
multimeter with an accuracy of +0.5% DCV or better and a 0
to 50ohm, 250 Watt adjustable resistive load is available.
If re-calibration is required, use the following procedures.
Locations of the electrical calibration on the main PCB are
shown in FIG. 7.1.
FIG. 7.1