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5-8. Relay Box
The power supply is directly connected to the relay
contacts. When these contacts are closed, 24
volts is supplied to the solenoids which are mounted
on the hydraulic mini-valves. One relay is used to
supply power to the pump/motor and is always
activated no matter what control function is se-
lected. The brake locking circuit relay is also
activated when any control function other than
BRAKE UNLOCK is
initially
selected.
Also, inside the relay box is a step-down trans-
former and full-wave rectifier which decreases the
voltage to 5-6 volts. This low voltage potential
controls the relays by the use of the hand-held
pendant control buttons. Basically the relays en-
able a 5-6 volt potential to control the 24 volt circuit.
The following tests will determine if the relay box is
functioning correctly.
a. Checking Relay Box Input Power
1. Connect power cord to table. Plug the power
cord into the 120VAC supply (wall receptacle).
Disconnect connector CN4, leave all other connec-
tors connected.
2. Using a DC voltmeter, test input power for
both the BATTERY and AC120V operating modes.
See figure 5-11. Meter should read approximately
24 -28 volts.
b. Test Results:
If you do not receive the correct meter readings,
the problem is in the input wiring, connectors or
components. If the correct readings are obtained,
proceed to the next step.
Figure 5-11. Relay Box Input
c. Checking Output to Pump
1. Make sure all connectors are connected and
activate the AC120V operating mode. See figure 5-
12.
82306-511
1-RED (+)
2-BLUE (-)
2
1
CN4
BATTERY MODE TEST (main power OFF)
5-PURPLE (+)
6-BLACK (-)
CN4
AC120V MODE TEST (main power ON)
CONNECTOR CN4 COLOR CODE
1
2
3
4
5
6
RED
BLUE
RED
BLACK
PURPLE
BLACK
7
8
9
10
11
12
WHITE
WHITE
YELLOW
GRAY
ORANGE
- - -
6
5
HN4
82306-517
1
2
Figure 5-12. Output to Pump
2. Test HN4 at pin 1(+) and pin 2(-) with a DC
voltmeter. Meter should read approximately 24-28
volts when any function button is activated. If no
voltage is present, use an ohmmeter to test the
continuity from HN4 to CN4 (red and black wires).
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