Check that all frame ground connections are clean and
tight in all devices on the system. Frame grounding is
indicated either by a braided cable or a green and yellow
wire.
5100 ground locations:
Bottom cover. center right side
CRT
mounting screen and frame
Power supply fan
motor
Raceway
Power switch
AC power box
Tape unit motor
AC capacitor
in
tape unit
TV monitor plug
5103 ground locations:
Left
front
corner
Right
front
corner
AC line cord
Flat cable shield clamp
Left rear
of
forms tractor
5106 ground locations:
Tape unit motor
AC capacitor
Cooling fan
Power switch
AC line cord
A1
board
Flat cable shield clamp
AC
Power Considerations
Checking
for
proper AC line voltage is a task that you
are familiar with. However. other aspects
of
the AC
power source are also very important. The AC line
voltage should not vary by more than
±1
0 % except
for
500 ms transients
of
+15%
to
-18%.
One type
of
AC power disturbance becoming more
frequent is fractional phase loss. This is a result
of
phase controlled SCRs controlling motors. ovens. or
other loads. These devices turn on their loads during
each phase and deplete the sine wave
of
energy.
AC
Power Terms
Current Carrying Ground:
This is
t~e
neutral line that is
connected
to
the neutral bus.
3-84
Neutral Bus: This bus bar is inside the power panel.
The other neutral buses should be tied
to
this bus. The
neutral bus should be tied
to
the ground bus only at the
main distribution panel.
Main Distribution Panel: This is the first power panel
inside
of
the customer's building. This panel is fed
directly from the power company lines. The ground bus
in
this panel is serviced by the service entrance ground.
Ground Bus: This bus bar is
in
the power panel. The
ground wire
for
the power source
of
the 5100. along
with
a wire into the panel from
an
approved earth
ground source. should connect
to
this bar.
Earth Ground: The definition depends upon local
electrical building codes. Usually.
an
earth ground
is
supplied in
two
forms:
1.
2.
A metal pipe running into the earth and containing
running water. Stagnant water or sump lines are
not good earth ground sources. nor are lines
broken by nonmetal connections.
A metal stake driven into the ground. The length
of
the stake and the depth
to
which it must be
driven into the ground depend on local codes.
Noncurrent Carrying Ground: This is the line from the
ground
in
the receptacle
to
the ground bus.
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