Equipment Safety - Pitney Bowes DI380 Series Service Manual

1 • Introduction
1.6

eQUIPMeNT sAFeTY

Just by walking around, you yourself may carry a threat to the equipment, in the form of a high voltage
electrostatic charge. Your body acts as a giant capacitor which can store large amounts of electricity.
Walking across a rug can charge you with several thousand volts, which can discharge in a spark up
to an inch long.
Digital equipment can be easily damaged or destroyed by static charges. Microprocessors and other
ICs contain tiny transistors not much more than a millionth of an inch across, which operate at 5 to
12 volts. You don't have to see a spark to ruin an IC — 50 volts is enough. Follow these guidelines to
protect sensitive equipment from static damage:
● Ground yourself before reaching into the equipment, or touching any circuit board or other electrical
component. Just touching a doorknob or metal workbench may be enough, but the best guarantee
is to turn the machine off but leave it plugged in, and ground yourself on the chassis, which is
grounded through the three-wire power cord. If you have access to one, bring a grounding strap
and use it.
● Be careful of rugs — even a few steps can recharge you. Re-ground yourself whenever you've
walked away and returned to the machine. Rugs are a major source of static buildup in the
body.
● Take greater precautions as the objects you handle get smaller. A board in the machine is better
protected than one which is not plugged in; a chip on a board is better protected than one in your
hand.
● Stay away from metal conductors. The plastic and resin that chips and boards are made of are
much better insulators than metal. It's most important to keep your hands away from any metal
which contacts the data. In particular, this means the long connector along the bottom of each
board, and the pins coming out of the chips. These signal and data lines are directly connected to
the fragile inner circuits of the chips. When handling a board, try not to touch the connector; when
handling a chip, try not to touch the pins.
1-4 SDT3233A DI380/DI425/SI3300/SI3500 Service Manual