HP 7470A Service Manual page 7

Section I
Model 7470A
The line power cord and power outlet
must have a protective earth (ground)
contact.
1-14. The 7470A primary power circuit can be con-
figured to operate from any one of the following power
sources at a line frequency of 48 to 66 Hz, single phase.
Maximum power used is 25 W.
1-15. Line voltage selection is identified on the label
visible in the small receased window in the rear panel.
Applying line voltage of 220 V or 240 V
to the plotter while the line voltage
selection is set for 100 V or 120 V
operation may damage the plotter
circuits.
1-16.
The line voltage selection may be changed to
conform to the line voltage in a particular a r e a Use
the following procedure.
F]
The following procedure should be per-
formed only by servicatrained person-
nel who are aware of the electrical shock
hazards involved.
a.
Set the plotter LINE switch to OFF ( 0 ) and dis-
connect the line cord.
b. Remove the plotter top case by removing the
screws indicated in Figure 1-1. Lift the rear of
the top case and the front will release. When
replacing, make sure the PAPER HOLD lever
extends through the case. and the tabs inside
the front of the top care align properly above
and below the bare plate.
11\1\1111"""
REMOVE THESE SCREWS
T O RELEASE TOP CASE
74704-2.1
Figure 1-1. Top Case Removal
c.
Line voltage selection is determined by the power
input connections to the transformer primary
windings. Table 1-2 lists the wire colors and
transformer contact connections for each line
voltage. The transformer pin numbers are iden-
tified on the power module molding. Figure 1-2
illustrates the connections for each voltage.
Change the wire connections a s required to con-
form to the desired line voltage selection.
Make sure the line fuse is correct
according to Table 1-3. The fuse holder
cap is the bayonet type. Press and
turn counterclockwise to remove, clock-
wise to lock.
d. Change the position of the line voltage label
block so that the voltage selected is right side
up. This block snaps in and out of the power
module molding.
Table 1-2. Line Voltage Selection
*Wire identification is by color code:
8 =CRY
928
= WHT:RED/GRY
958 = WHT:GRN/GRY
NOMINAL
LINE
VOLTAGE
100 V
120 V
220 V
240
V
TRANSFORMER PRIMARY CONNECTIONS*
PIN
1
8
8
8
8
PIN 2
928
NC
958
NC
PIN
3
958
928
NC
958
PIN
4
8
8
958
958
PIN 5
958
928
928
928
PIN 6
NC
958
8
8
PIN 7
928
958
928
928