Motorola MT512M, Basic Service Manual

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MAINTENANCE 6 - 3
Safe Handling of CMOS and LDMOS Devices
Complementary metal-oxide semiconductor (CMOS) devices are used in this family of terminals,
and are susceptible to damage by electrostatic or high voltage charges. Damage can be latent,
resulting in failures occurring weeks or months later. Therefore, special precautions must be taken
to prevent device damage during disassembly, troubleshooting, and repair. Handling precautions
are mandatory for CMOS circuits and are especially important in low humidity conditions. DO NOT
attempt to disassemble the terminal without first referring to the following CAUTION statement.
CAUTION: This terminal contains static-sensitive devices. Do not open the terminal unless
you are properly grounded. Take the following precautions when working on this unit:
• Store and transport all CMOS devices in conductive material so that all
exposed leads are shorted together. Do not insert CMOS devices into
conventional plastic “snow” trays used for storage and transportation of
other semiconductor devices.
• Ground the working surface of the service bench to protect the CMOS device.
We recommend using the Motorola Static Protection Assembly (part number
0180386A82), which includes a wrist strap, two ground cords, a table mat, and
a floor mat.
• Wear a conductive wrist strap in series with a 100k resistor to ground.
(Replacement wrist straps that connect to the bench top covering are
Motorola part number 4280385A59).
• Do not wear nylon clothing while handling CMOS devices.
• Do not insert or remove CMOS devices with power applied. Check all power
supplies used for testing CMOS devices to be certain that there are no voltage
transients present.
• When straightening CMOS pins, provide ground straps for the apparatus
used.
• When soldering, use a grounded soldering iron.
• If at all possible, handle CMOS devices by the package and not by the leads.
Prior to touching the unit, touch an electrical ground to remove any static
charge that you may have accumulated. The package and substrate may be
electrically common. If so, the reaction of a discharge to the case would cause
the same damage as touching the leads.
!