Download here - Snap-on Equipment

Signals that are active low or active on the falling edge are designated with an asterisk (*)following the signal
name, i.e. TRACK 00*, STROBE*. Typically the text will differentiate between a level sensitive or edge sensitive
signal.
A Functional block may use either an asterisk following the signal name (PUMP ON*) or a bar over the signal's
name (PUMP ON) to indicate that the signal is active low or on the falling edge.
OPEN COLLECTOR OUTPUTS
Some of the outputs are open collector, meaning that a pull-up resistor is used to "pull- up" the signal to Vcc.
Usually the pull-up resistor is at the signal's destination board. The Open Collector outputs are designated on the
diagrams with an O.C. marking at the edge connector. The FST should keep in mind the fact that open collector
drive may be used. A broken wire between the source board and the destination board will cause the source
board to appear to be defective (the signal will not be pulled-up, thus it will appear that the source board is not
outputting a signal).
HANDLING OF MOS IC AND OTHER STATIC SENSITIVE DEVICES
A majority of integrated circuits are high impedance devices. This characteristic makes them susceptible to
damage by electrostatic charges. Large electrostatic charges can build up in low humidity environments which if
discharged through IC terminals, may permanently damage the device.
To eliminate needless failures, use the following techniques when handling any circuit board, integrated circuit
chip or any other static sensitive device:
1. Do not remove the printed circuit board from the static protection packaging until it is ready for use.
2. Never remove or insert boards under power.
3. The correct procedure for removal of a Board from card rack or main equipment is as follows:
a. Equipment on which the repair is performed must be grounded.
b. Wear wrist strap and connect wrist strap to equipment or any available nearest ground (wrist strap
ground cord is included in field service kit).
c. Always grasp the Board from two opposite edges using the forefingers.
d. Place removed Board on grounded static dissipative mat (part of field service kit) when troubleshooting
or upgrading software.
4. When inserting Boards into a card rack or into main equipment:
a. Remove Board from original packaging on static dissipative material. Save all packaging for possible
reuse if required to ship defective Board.
b. Install Boards into unit using rules 3A, 3B, and 3C.
c. Package defective Boards into a shielded bag and then return in a reusable container.
5. Package IC chips or any other static sensitive device in conductive foam or an equivalent static dissipative
material which provides adequate static and physical protection.
6. Avoid any unnecessary contact with internal circuits.
7. Avoid setting Board's on static prone insulating surfaces such as paper, glass, rubber, and plastic.
8. Beware of friction generated static when:
a. Wearing silk or nylon garments.
b. Walking on carpets.
c. Scuffing rubber sole shoes.
NOTE: Relative humidity has a direct bearing on the magnitude of possible static charge
buildup; the lower the relative humidity, the higher the charge and vice versa.
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