HP 8447D Operation And Service Manual page 43

8447A-4
SERVICE NOTE
Supersedes:
None
HP MODEL 8447A AMPLIFIER
All Serials
PREVENTION OF AMPLIFIER DAMAGE DUE TO ELECTROSTATIC DISCHARGE
CAUTION
The input to the 8447A amplifier is very susceptible to damage from electrostatic discharge.
Before connecting any coaxial cable to the input jack of the amplifier, make certain that static
electricity buildup in the cable is completely discharged. This is best accomplished by shorting
the inner conductor of the cable to the outer conductor while simultaneously touching earth
ground. A small open-end wrench can be used to short the inner conductor to the outer conduc¬
tor, and the output jack of the amplifier provides a good earth ground to which the other end of
the wrench can be touched. The other end of the coaxial cable should be connected first before
going through this procedure. If the other end of the cable is connected to a signal source, make
sure the souce's power has been turned off.
A static-safe work station is highiy recommended when handling the coaxial cable. Such a station
should include a wrist strap in contact with bare skin connected to a conductive table mat
through a current-limiting one-megohm resistor. The table mat must be connected to earth
ground through another one-megohm resistor.
Once the coaxial cable is connected to the amplifier input, a discharge path to ground is estab¬
lished. Thus, any static electricity buildup on the cable will be bled off. Handling precautions
will not be necessary with the cable connected.
I/NS/WN
11 /84-53/BA
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OR WRITE,
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IN EUROPE, CALL YOUR
LOCAL HP SALES or SERVICE OFFICE OR WRITE,
Hewlett-Packard S.A., 7, rue du Bois-du-Lan Case Postale 365 CH 1217 Meyrin 1 - Geneva, Swit¬
zerland.
IN JAPAN,
Yokogawa-Hewlett-Packard Ltd,, 27-15, Yabe, 1 Chrome, Sagamlhara City, Kanagawa Prefecture, Japan 229.
Printed in U.S.A,