Keithley 2000-SCAN-20, Instruction Manual

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4-10 Service Information
Special handling of static-sensitive devices
CMOS and other high-impedance devices are subject to possible static discharge damage
because of the high-impedance levels involved. When handling such devices, use the
precautions listed below.
NOTE To prevent damage, assume all parts are static-sensitive.
1. Such devices should be transported and handled only in containers specially designed to
prevent or dissipate static buildup. Typically, these devices will be received in anti-static
containers made of plastic or foam. Keep these parts in their original containers until
ready for installation or use.
2. Remove the devices from their protective containers only at a properly grounded
workstation. Also, ground yourself with an appropriate wrist strap while working with
these devices.
3. Handle the devices only by the body; do not touch the pins or terminals.
4. Any printed circuit board into which the device is to be inserted must first be grounded
to the bench or table.
5. Use only anti-static type de-soldering tools and grounded-tip soldering irons.
Principles of operation
The following paragraphs discuss the basic operating principles for the
Model 2000-SCAN-20 and can be used as an aid in troubleshooting the card. The schematic
drawing of the card is shown on drawing number 2000-186 located at the end of
Section 5 .
Block diagram
Figure 4-6 shows a simplified block diagram of the Model 2000-SCAN-20. Key elements
include the relay drivers, relays, and power-up reset circuit. These various elements are
discussed in the following paragraphs.