MAINTENANCE
CAUTION
Do not use a fuse with a rating higher than
specified or instrument damage may occur. If
the instrument repeatedly blows fuses, locate
and correct the cause of the trouble before
replacing the fuse.
4. Install the new fuse and the carrier into the holder by
reversing the above procedure.
Table 6-2. Line Fuse Replacement
Line Keitbky
Voltage Fuse Type Part No.
105V~JZSV 3/l&4, 25w, Slo-Blo, 3AG
FU-29
ZOV-25OV l/lOA, UOV, Slo-Blo, 3AG Fu-‘m
6.3.2 Current Fuse
The ctitient fuse protects the 30mA and 3A ranges from
an input current greater than 3A. To replace the current
fuse, perform the~following steps:
1. Turn off the power and disconnect the power line and
testy leads.
2. Place the end of a flat-blade screwdriver into~the slot in
the fuse holder on the front panel. Press in slightly and
rotate the fuse
carrier
one-quarter
turn
counterclockwise. Release pressure and remove the fuse
carrier and the fuse.
3. Remove the defective fuse and replace it using Table 6-3
as a guide.
CAUTION
Use only the recommended fuse type. If a fuse
with a higher current rating is installed, instru-
ment damage may occur.
4. To replace the fuse carrier with the fuse, reverse the pro-
cedure in step 2.
Table 6-3. Currant Fuse Replacement
Fuse Type
/ Keithlcy Part No.
3A, UOV, 3AG, Normal-B10
Fu-82
6.4 CALIBRATION
Calibration should be performed every 12 months, or if
the performance verification procedures in Section 4 show
that the Model 199 is out of specificatibn. If any of the
calibration procedures in this section cannot be perform-
ed properly, refer to the troubleshooting information in this
s&on. If the problem persists, contact your Keithley
representative or the factory for further information.
NOTE
Check that the instrument is set to the proper line
frequency before proceeding with calibration,
The entire calibration procedure may be performed
without having to make any internal adj~ustments if high
frequency (7OkHz) has been verified, as explained in
paragraph 6.4.10, step 5. Calibration can be performed from
the front panel or over the IEEE-488 bus.
NOTE
A “CONFLICT’ error will be displayed, and the
CONFLICT error bit in the Ul status word will be
set when trying to calibrate the instrument while
it is in an improper state (i.e. dB). Also, if an
“UNCAL” error occurs, be sure to check the line
frequency setting before performing calibration.
6.4.1 Recommended Calibration Equipment
Table 6-4 lists recommended calibration equipment. Alter-
nate equipment may be used as long as equipment ac-
curacy is at least as good as the specifications listed in the
table.
6-2
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