Chapter
5
Troubleshooting
General Problems
Nothing Happens at Turn-on
Make sure that the power entry module on the rear panel is set for the AC line voltage for your region,
that the correct fuse is installed, and that the line cord is inserted all the way into the power entry
module. The selected line voltage may be seen through the clear window, just below the fuse.
When the unit is plugged in and turned "ON", the unit's program version number will be briefly
displayed. Then the self-tests should execute.
Reset Procedure
If the unit displays no sensible message, the "cold boot" procedure may fix the problem. To reset the
instrument, turn the unit off. Then, while holding the backspace key ([←]), turn the unit "ON". This
procedure initializes the RAM and recalls the factory calibration and default values. The default
parameter values and instrument settings are listed in Volume 1 of this manual.
Internal Fuse Check
If the unit powers on correctly but makes unstable or wildly inaccurate readings, the internal fuse may
be blown. This can also cause the unit to fail the self-test (Out Err3). To change this fuse, the top of
the unit must be removed. To do this, first turn off and unplug the unit. Next remove the four screws
located on the bottom at the comers of the unit. Place the unit right side up on its feet and gently slide
the plastic top off the metal base.
It is necessary to slide the top gradually off the fixture and the back panel, since it fits tightly over
these. When the top is removed, stand it on its left side near the unit to avoid damaging the front
panel cables. The internal fuse is located near the fixture, on the right hand side of the unit. Remove
the old fuse and inspect it for damage. If it is damaged, replace it with a 250V, F250mA fuse.
Replace the top, taking care to align it over the fixture and rear panel. Finally, replace the four screws
and verify that this fixed the unit.
External Bias Fuse Check
If the unit makes unstable or wildly inaccurate reading when an external bias is applied, the external
bias fuse may be blown. To change it, power off and unplug the unit. Use a screwdriver to remove
the fuse holder and the fuse from the rear panel. Check the fuse with an Ohmmeter, if it is damaged,
replace it with a 250V, F250mA fuse. Replace the fuse holder and fuse and verify that the unit
operates correctly.
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