Lake Shore Model 340 Temperature Controller User’s Manual
Service
11-1
CHAPTER 11
SERVICE
11.0 GENERAL
This chapter provides general service information for the Model 340 Temperature Controller. There is no
calibration procedure for the Model 340. There are no serviceable parts inside the Model 340. If you have any
specific problems with your Model 340, please call Lake Shore.
General maintenance precautions are defined in Paragraph 11.1. Electrostatic discharge is defined in
Paragraph 11.2. Paragraph 11.3 provides general maintenance information. Changing power settings and
fuse rating is described in Paragraph 11.4. Rear panel connector definitions are provided in Paragraph 11.5.
Serial cable and adapters are described in Paragraph 11.6. A top of enclosure remove and replace procedure
is provided in Paragraph 11.7. Software EPROM and Precision Option NOVRAM replacement is detailed in
Paragraph 11.8. Finally, error messages are described in Paragraph 11.9.
11.1 GENERAL MAINTENANCE PRECAUTIONS
The following are general safety precautions that are not related to any specific procedure and therefore do
not appear elsewhere in this publication. These are recommended precautions that personnel should
understand and apply during the maintenance phase.
Keep away from live circuits. Installation personnel shall observe all safety regulations at all times. Turn off
system power before making or breaking electrical connections. Regard any exposed connector, terminal
board, or circuit board as a possible shock hazard. Components which retain a charge shall be discharged
only when such grounding does not result in equipment damage. If a test connection to energized equipment
is required, make the test equipment ground connection before probing the voltage or signal to be tested.
Do not install or service equipment alone. Personnel shall not under any circumstances reach into or enter
any enclosure for the purpose of servicing or adjusting the equipment without immediate presence or
assistance of another person capable of rendering aid.
11.2 ELECTROSTATIC DISCHARGE
Damage can occur to electronic parts, assemblies, and equipment from electrostatic discharge (ESD). ESD is
defined as 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 in conjunction with nonconductive
garments and floor coverings generates and retains static electricity. Simply walking across a carpet in low
humidity can generate up to 35,000 volts of static electricity.
Trends in technology are toward greater complexity, increasing packaging density, and hence thinner
dielectrics between active elements, resulting in electronic devices becoming even more sensitive to ESD.
Various electronic parts are more ESDS than others. These can be damaged by ESD levels generated by
personnel testing, handling, repairing, and assembling electronic components without their being aware that a
discharge of static electricity has even occurred. Many ESDS devises such as semiconductors, thick and thin
film resistors, chips and hybrid devises, and piezoelectric crystals can be damaged or destroyed by ESD
levels of a few hundred volts, which is far below the 4000 volt human threshold of awareness. Discharges
below this level cannot be seen, felt, or heard.