647 Chair Back Up / Down Function Troubleshooting
This illustration shows only the components that affect the Back Up / Down function. A detailed description of Back Up / Down operation appears below.
•If power light is OFF: Refer to: Power to the Chair for troubleshooting.
•If power light is ON: Proper voltage is present at PC board.
•Black and white wires supply 48-54 VAC to power circuitry for the Base and Back actuators.
On models with rotational base, the main system transformer connections are supplied thru the for troubleshooting. Rotational Base PC board, not shown.
Is there power to the chair?
When voltage is present at the PC board, the power light is illuminated.
Refer to: Power to the Chair for description of current flow to the PC board.
Power to Foot Control / Touch Pads
Circuitry on the PC board supplies 8-10 VAC to the foot control and touch pads.
Back Up Operation
When the Back Up function is activated, current flows thru the foot control / touch pads to the main PC board. Circuitry on the main PC board supplies approximately 48 VDC to the back actuator motor.
The actuator motor runs and raises the back section.
Actuator motor runs until
1.Foot control / touch pad button is released.
2.Back Up limit switch is tripped.
3.Emergency Stop button is pressed.
4.Position sensor detects upper limit.
5.Overcurrent protection tripped
6.Software timeout is reached, 30 seconds.
Back Down Operation
When the Back Down function is activated, current flows thru the foot control / touch pads to the main PC board. Circuitry on the main PC board supplies approximately 48 VDC to the back actuator motor.
The actuator motor runs and lowers the back section.
Actuator motor runs until
1.Foot control / touch pad button is released.
2.Back Down limit switch is tripped.
3.Crash Avoidance System activated.
4.Emergency Stop button is pressed.
5.Position sensor detects lower limit.
6.Overcurrent protection tripped
7.Software timeout is reached, 30 seconds.
Refer to: Crash Avoidance System for a detailed description of crash position, and the functions that are disabled.
