Braun VISTA Series Installation & Service Manual page 48

5 Ampere Circuit Breaker: This circuit breaker is a
single pole, manual reset, thermally-operated circuit
protection device rated at 5 amperes that protects a
circuit from being overloaded beyond the safe
current carrying capacity of the circuit. When the
breaker heats up to a certain temperature, it inter-
rupts the source of current and, when the cause of
the overload is corrected and it cools back down, it
may be reset to provide current.
External Electrical "Up/Fold" Solenoid: When
the platform is below floor level, pressing the UP
switch energizes this solenoid. The solenoid directs
current to the pump motor which powers the hydrau-
lic pump to raise the platform. The Up/Fold
microswitch is activated when the platform reaches
floor level. This interupts the UP control switch
circuit which de-energizes the solenoid and removes
current to the pump motor and stops the platform.
Releasing the UP switch will also de-energize the
solenoid removing current to the pump motor and
stopping the raising function.
Pressing the FOLD switch then energizes the Up/
Fold solenoid through the fold circuit. The solenoid
in turn directs current to the pump motor to fold the
platform. Releasing the FOLD switch de-energizes
the solenoid removing current to the pump motor
and stopping the folding function.
Note: When the platform reaches the stowed (fully
folded) position, the Hydraulic Platform Sensor
Pressure Switch is activated (pre-set pressure
reached). The activated Pressure switch shuts the
pump moter off also. See page 39 for further details.
M258 Solenoid/Hydraulic Valve: VL917 lift
models are equipped with the M258 hydraulic pump
(further details in Hydraulic section). The M258
features a pump-mounted Down solenoid/hydraulic
valve (details follow).
When the platform is in the stowed (fully-folded)
position, pressing the UNFOLD switch energizes the
Page 36
Systems Descriptions
Electrical (continued)
Down solenoid/valve. When the platform reaches
floor level, the solenoid/valve is de-energized by the
Unfold/Down microswitch circuit. Releasing the
UNFOLD switch also de-energizes the solenoid/
valve.
The Down solenoid/hydraulic valve is also energized
while the DOWN switch is pressed when the plat-
form is fully unfolded. The solenoid/valve will
remain energized until the DOWN switch is re-
leased.
Troubleshooting: A problem with the solenoid/valve
can be electrical or hydraulic. Follow the Quick-
Check troubleshooting procedure when trouble-
shooting.
Quick-Check:
Read warning
posted at right!
Remove all rings,
watches, etc. prior to
doing any electrical
work near the pump
motor.
With the lift stowed,
hold a paper clip (or
other magnetically
attracted object)
near the center
threaded post on the
solenoid/valve while
pressing the UN-
FOLD switch (stand
clear of platform).
If the solenoid post
does not magneti-
cally attract the paper clip, there is an electrical
problem. If attracted, there is a hydraulic problem.
Note: If this solenoid post is bent at all, the hydrau-
lic valve will not operate.
W ARNING
Risk of electrical
shock! Use extra
care when making
electrical connec-
tions or performing
electrical tests.