647 Chair Back Actuator / Limit Switches Test and Repair
This illustration shows the back limit switches and the three serviceable components of the back actuator. Use the table below to isolate the malfunction.
|
Problem |
Required Action |
|---|---|
|
Motor runs, but makes grinding noise. |
Clean / lube actuator threads. Replace actuator if necessary. |
|
Motor runs, but chair does not move. |
Inspect / replace motor coupler. |
|
Motor does not run. |
Perform Limit Switch / PCB Harness Test |
Do not adjust the individual switches! The limit switches and bracket must be replaced as a complete assembly.
Limit Switch / PC Board Harness Test
1.Disconnect harness from J11 on main PC board.
2.Place one meter probe on the common, white.
3.Place the other probe on the wire corresponding the desired switch, see illustration.
Check switch tripped and untripped.
| Back Down switch tripped Or Back Up switch untripped | |
|---|---|
|
Meter Reading |
Required Action |
|
OL |
Limit switch / harness OK, Perform Actuator Motor Test |
|
Less than 10 ohms |
Perform Limit Switch Harness Test |
| Back Down switch untripped Or Back Up switch tripped | |
|---|---|
|
Meter Reading |
Required Action |
|
OL |
Perform Limit Switch Harness Test |
|
Less than 10 ohms |
Limit switch / harness OK, Perform Actuator Motor Test |
Limit Switch Harness Test
1.Unplug the appropriate limit switch harness.
2.Measure continuity.
|
When |
Meter reading should be |
|---|---|
| Actuator Full Up |
White to Black - Open |
|
White to Red - Closed |
|
| Actuator Full Down |
White to Black - Closed |
|
White to Red - Open |
|
| Actuator Midway Point |
White to Black - Closed |
|
White to Red - Closed |
Actuator Motor Test
1.Tag and disconnect back actuator wires, J3 and J4.
2.Place meter probes on actuator wires. Check meter reading.
|
Meter Reading |
Required Action |
|---|---|
|
1 to 10 ohms |
Actuator motor OK, Perform Motor Ground Test |
|
OL or less than 1 ohm |
Replace actuator motor |
Motor Ground Test
1.Place one meter probe on actuator wire, J3. Place other probe on PC board ground wire.
2.Check meter reading.
3. Repeat for J4.
|
Meter Reading |
Required Action |
|---|---|
|
OL or less than 1 ohm |
Motor harness OK, Perform PC Board Test |
| Less than 1 ohm |
Replace actuator motor |
PC Board Test
This test cannot be performed with the back section in the maximum or minimum position.
1.If necessary, reposition the back section
2.Move base section so that it is approximately halfway between its maximum and minimum positions.
3.Tag, then disconnect back actuator wires from J3 and J4.
4.Move wire from J1 to J3. Move wire from J2 to J4.
The base limit switches will not stop movement during this test. Do not run past max / min positions.
5.Press and hold Back Up button for 5 seconds. Does the base section move up, then stop and beep? If YES, go to Step 6. If NO, replace PC board.
6.Press and hold Back Down button for 5 seconds. Does base section move down, then stop and beep? If YES, PC board is OK. If NO, replace PC board.
