Pulsar TCF-10B, System Manual, Page: 99 / 249

8.5.4 Servicing Components
Mounted Directly on Heat
Sinks
1. Remove the heat sink and bracket from the
chassis by loosening the securing devices.
2. Remove the transistor, diode, or other device
from the heat sink.
3. When replacing the transistor, diode, or other
device, make certain that the device and the
heat sink make secure contact for good heat
dissipation. Mount a device first on the heat
sink, and then on the board. Also, make sure
that you replace all insulators, washers, spring
washers and other mounting hardware as you
originally found them.
We recommend a very light coating of DC-4
(Dow-Corning 4 Compound Silicon Lubri-
cant) for transistors and diodes that are
mounted on heat sinks.
8.5.5 Servicing Metal Oxide
Semiconductor (MOS) Devices
MOS devices may be vulnerable to static changes.
Be sure to observe the special precautions
described below both before and during assembly.
Precautions to take before assembly:
• Avoid wearing silk or nylon clothing, as
this contributes to static buildup.
• Avoid carpeted areas and dry environ-
ments.
• Discharge body static by placing both
hands on a metal, earth-grounded surface.
Precautions to take during assembly to avoid the
possibility of electrostatic discharge:
• Wear a ground strap during assembly
• Avoid touching electrically-conductive
circuit parts by hand
• When removing a module from the chassis,
always place it on a conductive surface
which is grounded through a resistance of
approximately 100 K ohms
• Make sure that all electrically-powered test
equipment is properly grounded.
Page 8–4 December 1996
TCF–10B System Manual
Technologies, Inc.
NOTE
Before touching a module with a test probe,
connect the ground lead from the test
equipment to the module. Always discon-
nect the test probe before removing the
ground lead equipment.