1 • Introduction
Electrostatic Discharge (ESD) Procedures
Follow these guidelines to protect sen si tive equipment from static damage:
Always use a wrist grounding strap and anti-static mat when working
on equipment sensitive to electrostatic discharge. These items are fur-
nished in the ESD Field Service Kit, L-8351.
Ground yourself before reaching into the equip ment, or touch ing any
circuit board or other electrical component. Just touch ing a doorknob or
metal work bench may be enough, but the best guarantee is to turn the
machine off but leave it plugged in, and ground your self on the chassis,
which is grounded through the three-wire power cord.
Be careful of rugs—even a few steps can recharge you. Re-ground
yourself whenever you've walked away and re turned to the ma chine.
Rugs are a major source of static build up in the body.
Take greater precautions as the objects you handle get smaller. A board
in the machine is better protected than one that 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.
DM300c/DM400c/DM475 Service Manual (SV61801 Rev. D)