Lakeshore 325, Руководство пользователя, Страница: 131 / 166

Lake Shore Model 325 Temperature Controller User’s Manual
Service 8-3
8.5 FUSE REPLACEMENT
Use the following procedure to remove and replace a line fuse.
WARNING: To avoid potentially lethal shocks, turn off controller and disconnect it from AC power before
performing these procedures.
CAUTION: For continued protection against fire hazard, replace only with the same fuse type and rating
specified for the line for the line voltage selected.
NOTE: Test fuse with an ohmmeter. Do not rely on visual inspection of fuse.
1. Locate line input assembly on the instrument rear panel. See Figure 8-2.
2. Turn power switch Off ( O ).
3. Remove instrument power cord.
4. With a small screwdriver, release the drawer holding the line voltage selector and fuse.
5. Remove existing fuse(s). Replace with proper Slow-Blow (time-delay) fuse ratings as follows:
100/120 V 1.6 A T 250 V 5 × 20 mm
220/240 V 1.6 A T 250 V 5 × 20 mm
6. Re-assemble line input assembly in reverse order.
7. Verify voltage indicator in the line input assembly window.
8. Connect instrument power cord.
9. Turn power switch On (
l
).
8.6 ELECTROSTATIC DISCHARGE
Electrostatic Discharge (ESD) may damage electronic parts, assemblies, and equipment. ESD is a transfer of electrostatic
charge between bodies at different electrostatic potentials caused by direct contact or induced by an electrostatic field.
The low-energy source that most commonly destroys Electrostatic Discharge Sensitive (ESDS) devices is the human
body, which generates and retains static electricity. Simply walking across a carpet in low humidity may generate up to
35,000 V of static electricity.
Current technology trends toward greater complexity, increased packaging density, and thinner dielectrics between
active elements, which results in electronic devices with even more ESD sensitivity. Some electronic parts are more
ESDS than others. ESD levels of only a few hundred volts may damage electronic components such as semiconductors,
thick and thin film resistors, and piezoelectric crystals during testing, handling, repair, or assembly. Discharge voltages
below 4000 V cannot be seen, felt, or heard.
8.6.1 Identification of Electrostatic Discharge Sensitive Components
The following are various industry symbols used to label components as ESDS.
8.6.2 Handling Electrostatic Discharge Sensitive Components
Observe all precautions necessary to prevent damage to ESDS components before attempting installation. Bring the
device and everything that contacts it to ground potential by providing a conductive surface and discharge paths. As a
minimum, observe these precautions:
1. De-energize or disconnect all power and signal sources and loads used with unit.
2. Place unit on a grounded conductive work surface.
3. Ground technician through a conductive wrist strap (or other device) using 1 M

series resistor to protect operator.