Service manual

Repair and
Maintenance
Guidelines
This section provides guidelines for repairing and maintaining the FET
Multiplexer including:
• ESD precautions
• Soldering printed circuit boards
• Post-repair safety checks
ESD Precautions Electrostatic discharge (ESD) may damage static sensitive devices in the
module. This damage can range from slight parameter degradation to
catastrophic failure. When handling the module observe the following
guidelines:
• Always use a static-free work station with a pad of conductive rubber or
similar material when handling module components.
• If a device requires soldering, be sure the assembly is placed on a pad of
conductive material. Also, be sure that you, the pad, and the soldering
iron tip are grounded to the assembly.
Soldering Printed
Circuit Boards
The etched circuit board of this module has plated-through holes that
provide a solder path to both sides of the insulating material. Soldering can
be done from either side of the board with equally good results. When
soldering to any circuit board, keep in mind the following guidelines:
• Avoid unnecessary component unsoldering and soldering. Excessive
replacement can result in damage to the circuit board, adjacent
components, or both.
• Do not use a high power soldering iron on etched circuit boards, as
excessive heat may lift a conductor or damage the board.
• Use a suction device or wooden toothpick to remove solder from
component mounting holes. When using a suction device, be sure that the
equipment is properly grounded.
Post-Repair Safety
Checks
After making repairs to the module, inspect the module for any signs of
abnormal internally generated heat, such as discolored printed circuit boards
or components, damaged insulation, or evidence of arcing. Determine and
correct the cause of the condition. Then perform Test 2-1 as described in
Chapter 2 — Verification Tests to verify that the module is functional.
4-8 Service