Lake Shore 370, Руководство пользователя

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Lake Shore Model 370 AC Resistance Bridge User’s Manual
8.9 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 volts 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 volts cannot be seen, felt, or heard.
8.9.1 Identification of Electrostatic Discharge Sensitive Components
The following are various industry symbols used to label components as ESDS.
8.9.2 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
Ω
series resistor to protect operator.
4. Ground any tools, such as soldering equipment, that will contact unit. Contact with operator's hands provides a
sufficient ground for tools that are otherwise electrically isolated.
5. Place ESDS devices and assemblies removed from a unit on a conductive work surface or in a conductive container.
An operator inserting or removing a device or assembly from a container must maintain contact with a conductive
portion of the container. Use only plastic bags approved for storage of ESD material.
6. Do not handle ESDS devices unnecessarily or remove from the packages until actually used or tested.
8.10 FIRMWARE REPLACEMENT
There are three integrated circuits (ICs) that may potentially require replacement. See Figure 8-4 for IC locations.
• Input Microcontroller (U14) – Contains software that configures the inputs, takes readings, and performs control
functions. Has a sticker on top labeled “M370IF.HEX” and a version number.
• Main Firmware Erasable Programmable Read Only Memory (EPROM) (U104) – Contains the user interface software.
Has a sticker on top labeled “M370MF.HEX” and a date.
• Non-Volatile Random Access Memory (NOVRAM) (U107) – Contains instrument settings and user curves. The
NOVRAM is replaced when the customer purchases a Model 8002-05-370 CalCurve™. Refer to Paragraph 7.2.
Use the following procedure to replace any of these ICs.
1. Follow the top of enclosure
REMOVAL
procedure in Paragraph 8.8.
2. Locate the IC on the main circuit board. See Figure 8-4. Note orientation of existing IC.
Service 8-9