SECTION 7
Maintenance
7.1 INTRODUCTION
This section contains information necessary to maintain,
calibrate, and troubleshoot the Model 486/487. The line
fuse replacement procedure is also included.
CAUTION
Donotuseafusewitha highermrrentrating
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. See
troubleshooting information in this section.
WARNING
The procedures in this section are for use
only by qualified sexvice personnel. Do not
perform these procedures unless qualified
to do so. Many of the steps in this seclion
may expose you to potentially lethal volt-
ages that could result in personal injury or
death if normal safety precautions are not
3. Install the new fuse and the fuse carrier into the
holder by reversing the above procedure.
Table 7-1. Line Fuse Selection
observed.
7.2 LINE FUSE REPLACEMENT
A rear panel fuse located adjacent to the line voltage
switch protects the power line input of the instrument. If
the fuse needs to be replaced (line voltage switch setting
chmged or suspacted blown fuse), perform the following
steps:
WARNING
Make sure the instrument is disconnected
from the power line and other equipment
before replacing the fuse.
7.3 CALIBRATION
Calibration should be performed every 12 months, or if
the parfo-ce verification procedures in Section 5
showthattheModel486/487isout ofspecification.Ifany
of the calibration procedures in this section cannot be
performed properly, refer to the troubleshooting infor-
mation in this section. If the problem persists, contact
your Keithley representative or the factory for further in-
formation.
I. With the power off, place the end of a flat-blade
SaewdriverintotheslotintherearpanelLINEFUSE
h~lder.Pushingentlyandrotatethefusecanierons-
quarter turn counterclodcwise. Release pr-e on
the holder and its internal spring will push the fuse
and carrier out of the holder.
2. Remove the fuse and replace it with the type mom-
mended in Table 7-l.
7.3.1
Recommended Calibration
Equipment
Table 7-2 lists recommended calibration equipment. Al-
temate equipment may be used as long as equipment ac-
aracy is at least as good as the sp&catiow listed in the
table.
7-1
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