647 Chair Position Sensors Test and Repair

647 Chair Position Sensors

1.Verify position sensor shoulder bolts are tight, 50 ft-lbs.

This step does not apply to the Base sensor.

2.Perform Output Voltage Test, at the Sensor.

This test must always be performed first. The results of this test determine the next required action.

Sensor

Affected Function
Back Sensor

Back Up / Down

Crash Avoidance System

Position Programming
Tilt Sensor

Tilt Up / Down

Crash Avoidance System

Position Programming
Base Sensor

Base Up / Down

Crash Avoidance System

Position Programming

647 Chair Output Voltage Test at the Sensors

1.Set meter to VDC

2.Place meter probes on proper terminals, See illustration.

3.Run desired function up and down. Watch meter reading as function moves.

Meter Reading

Required Action

Voltage steadily increases / decreases as function moves up / down

Perform Output Voltage Test at PC Board.

Voltage does not change, or changes erratically moves up / down

Perform Supply Voltage Testing at the Sensors.

1.Disconnect the White and Black wires at J7 and J8 on Main PC Board.

2.Connect Black wire to J7 and White wire to J8.

3.Perform Output Voltage Test on the Tilt Up function by pressing the Tilt Down button.

Caution

Do not run Tilt Up function beyond the halfway position.

4.Reconnect White wire to J7 and Black wire to J8.

5.Perform Output Voltage Test on the Tilt Down function.

Output Voltage Testing at the PC Board

1.Set meter to VDC.

2.Place meter probes on proper wires. See illustration.

3.Run desired function up and down. Watch meter reading as function moves.

Each sensor has a different voltage range. The important thing to watch for is whether the voltage changes as the functions moves.

Meter Reading

Required Action

Voltage steadily increases / decreases as function moves up / down

Replace PC Board. See Note.

Voltage does not change, or changes erratically moves up / down

PC board OK. Inspect wire harness connections.

Before replacing PC board, be sure shoulder bolt at the sensor pivot point is tight. If bolt is loose, tighten it, then recalibrate PC board and check for proper operation.

647 Chair Supply Voltage Testing at the Sensors

1.Set meter to VDC.

2.Place meter probes on proper wires. See illustration. Check meter reading.

3.With meter probes in the same position, run Base function to max. / min. position. Check reading as function moves.

Meter Reading

Required Action

2 to 4 VDC

Perform Position Sensor Adjustment. Replace position sensor if necessary.

Less than 2 VDC or more than 4 VDC

Perform Supply Voltage Test at the PC Board

Reading changes erratically as Base moves up / down.

Perform Supply Voltage Test at the PC Board

647 Chair Supply Voltage Test at PC Board

1.Set meter to VDC.

2.Place meter probes on proper wires. See illustration. Check meter reading.

Meter Reading

Required Action
2 to 4 VDC

Replace wire harness between the sensor and junction board or between the junction board and PC board

Less than 2 VDC or more than 4 VDC

Replace PC board

If initial reading is less than 2 VDC or more than 4 VDC, unplug J11 connector and check meter reading at pins on PC board, same location.

Meter Reading

Required Action

2 to 4 VDC

Replace sensor wire harness

<2 VDC

Replace PC board

>4 VDC

Replace PC board

647 Chair Installation and Adjustment of Position Sensors

Sensor

Function Position

Voltage Reading for SNs V2200 thru V921393

Base

all the way up

1.7 to 2.1 VDC

Back

all the way up

2.4 to 2.6 VDC

Tilt

all the way down

1.8 to 2.1 VDC

1.Remove main PC board cover.

2.Place meter probes as shown to test desired sensor.

3.Position chair function as indicated in the chart. Turn sensor knob until voltage reading is in the indicated range.

Equipment Alert

If position sensor wiring is disconnected you must recalibrate the PC board. Failure to do so will cause the chair to malfunction.

4.Perform PC Board Calibration Procedure. Refer to: Main PC Board