630 Chair Troubleshooting Chart

Symptom

Probable Cause

Check

Solution

No functions will operate. No power at chair receptacles.

Facility supply voltage.

Power cord connections at wall outlet and Power Entry Module at base of chair.

Secure power cord connections.

Facility circuit breaker.

Reset facility circuit breaker if necessary.

Power Supply PC Board fuse(s) blown.

Test F1 and F2 fuses on Power Supply PC Board.

Replace faulty fuse(s).

Loose wire connection.

Wire connection between Power Entry Module and Power Supply PC Board.

Secure loose wire connections.

Loose Power Toroid wire connections.

Wire connections at J9 and J10 on Power Supply PC Board.

Secure loose wire connections.

Power Toroid malfunctioning.

Refer to: Power Toroid

Replace Power Toroid.

No functions will operate. Power at chair receptacles.

System malfunction.

Error code on Machine Control PC Board.

Refer to: Error Codes

Foot / Hand control.

Try activating functions from both foot and hand controls.

Replace faulty hand / foot control.

Power Toroid malfunctioning.

Refer to: Power Toroid

Replace Power Toroid.

Symptom

Probable Cause

Check

Solution

No power at chair receptacle(s). All other functions work

Chair circuit breaker.

If chair circuit breaker is tripped.

Reset chair circuit breaker located at the base of chair, press to reset.

Loose wire connection.

Wire connections at J11 on Power Supply PC Board and chair receptacle.

Secure loose wire connections.

Chair Receptacle.

Voltage at receptacle.

Replace faulty receptacle.

Power Toroid malfunctioning.

Refer to: Power Toroid

Replace Power Toroid.

Symptom

Probable Cause

Check

Solution

When any control button is pressed, the chair sounds a series of three beeps. No functions operate.

Control Lockout is enabled.

Refer to: Control Lockout

Press and hold the Stop and Back Down buttons simultaneously for two seconds. You will hear a single “Beep” to indicate control lockout is enabled / disabled.

When any control button is pressed, nothing happens. No “beeps”, no movement, ect.

Faulty controller.

Refer to: Wired Controls

Replace faulty controller.

Symptom

Probable Cause

Check

Solution

When any control button is pressed, the chair sounds a series of three beeps. No functions operate.

Control Lockout is enabled.

Refer to: Control Lockout

Press and hold the Stop and Back Down buttons simultaneously for two seconds. You will hear a single “Beep” to indicate control lockout is enabled / disabled.

When any control button is pressed, that controller sounds a single “beep”. All functions operate.

Low battery.

Refer to: Wireless Controls

Replace batteries. size: AA

Faulty controller.

Refer to: Wireless Controls

Replace faulty controller.

When any control button is pressed, nothing happens. No “beeps”, no movement, ect.

Controller not associated to chair.

Refer to: Association Procedure

Perform Association Procedure.

Faulty controller.

Refer to: Wireless Controls

Replace faulty controller.

Symptom

Probable Cause

Check

Solution

Tilt, Back, and Foot functions will not operate. Base function does operate.

System malfunction.

Error code on Machine Control PC Board.

Refer to: Error Codes

Power Supply PC Board fuse(s) blown.

Test F3 and F4 fuses on Power Supply PC Board.

Replace faulty fuse(s).

Loose wire connection.

Wire connections at J3 on Power Supply PC Board and J13 on Motor Control Hub Board.

Secure loose wire connections.

Wire connections at J16 on Machine Control PC Board and J14 on Motor Control Hub PC Board.

Secure loose wire connections.

Symptom

Probable Cause

Check

Solution

No Base Up.

Active Sensing Technology™ activated.

For obstruction under foot section.

Remove object from under foot section.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to:Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to:Wireless Controls Malfunctioning

Foot Smart Sensor switches.

Check wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to:Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to:Smart Sensor Switches

Replace Switch(es).

Base Up limit switch.

Wire connections at J5 on Power Supply PC Board and at limit switch.

Secure wire connections. Refer to:Fuses and Connections

Test limit switch. Refer to:Base Actuator / Limit Switches

Replace limit switch.

Base Up Overtravel limit switch.

Wire connections at J5 on Power Supply PC Board and at limit switch.

Secure wire connections. Refer to:Fuses and Connections

Test limit switch. Refer to:Base Actuator / Limit Switches

Replace limit switch.

No Base Up or Base Down.

Active Sensing Technology™ activated.

For obstruction under foot section.

Remove object from under foot section.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Foot Smart Sensor switches.

Check wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to:Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to:Smart Sensor Switches

Replace Switch(es).

Loose wire connections.

Wire connections at J5, J6 and J7 on Power Supply PC Board.

Secure wire connections. Refer to:Fuses and Connections

Power PC Board fuse blown.

Test F5 fuse on Power Supply PC Board.

Replace faulty fuse. Refer to:Fuses and Connections

Base Up Overtravel limit switch.

Wire connections at J5 on Power Supply PC Board and at limit switch.

Secure wire connections. Refer to:Fuses and Connections

Test limit switch. Refer to:Base Actuator / Limit Switches

Replace limit switch.

Motor runs, but chair does not move.

Motor coupler broken.

Motor coupler. Refer to:Base Actuator / Limit Switches

Replace motor coupler.

Base Up / Down noisy, grinding or squeaking.

Actuator threads dry.

Actuator threads.

Clean and lubricate base actuator threads. Refer to:Base Actuator / Limit Switches

Base Actuator.

Run chair up and down, if squeaking or grinding continue check base actuator.

Replace base actuator.

Symptom

Probable Cause

Check

Solution

No Back Up.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Back Up limit switch.

Wire connections at J12 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to:Fuses and Connections

Test limit switch. Refer to:Back Actuator / Limit Switches

Replace limit switch.

Back Up Overtravel limit switch.

Wire connections at J12 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to:Fuses and Connections

Test limit switch. Refer to:Back Actuator / Limit Switches

Replace limit switch.

No Back Down.

Active Sensing Technology™ activated.

Position of chair. Refer to:Active Sensing Technology™

Activate Base Up and Tilt down, then try Back Down again.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Back Down limit switch.

Wire connections at J12 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to:Fuses and Connections

Test limit switch. Refer to:Back Actuator / Limit Switches

Replace limit switch.

Back Down Overtravel limit switch.

Wire connections at J12 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to:Fuses and Connections

Test limit switch. Refer to:Back Actuator / Limit Switches

Replace limit switch.

No Back Up or Back Down.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Loose wire connections.

Wire connections at J10, J11 and J12 on Motor Control Hub PC Board.

Secure wire connections. Refer to:Fuses and Connections

Motor Control Hub PC Board fuse blown.

Test F3 fuse on Motor Control Hub PC Board.

Replace faulty fuse. Refer to:Fuses and Connections

Back Up and/or Down Overtravel limit switch.

Wire connections at J12 on Motor Control Hub PC Board and at limit switch(es).

Secure wire connections. Refer to:Fuses and Connections

Test limit switch(es). Refer to:Back Actuator / Limit Switches

Replace limit switch(es).

Motor runs, but chair does not move.

Motor coupler broken.

Motor coupler. Refer to:Back Actuator / Limit Switches

Replace motor coupler.

Back Up / Down noisy, grinding or squeaking.

Actuator threads dry.

Actuator threads.

Clean and lubricate back actuator threads. Refer to:Back Actuator / Limit Switches

Back Actuator.

Run back up and down, if squeaking or grinding continue check back actuator.

Replace back actuator.

Symptom

Probable Cause

Check

Solution

No Tilt Up.

Active Sensing Technology™ activated.

For obstruction on the top of column.

Remove object from the top of the column.

For obstruction under the foot section.

Remove object from under the foot section.

Position of chair. Refer to: Active Sensing Technology™

Activate Base Up and Back Up, then try Tilt Up again.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Seat Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switch.

Secure wire connections. Refer to: Fuses and Connections

Check two pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch(es).

Foot Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch(es).

Tilt Up limit switch.

Wire connections at J8 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Tilt Actuator / Limit Switches

Replace limit switch.

Tilt Up Overtravel limit switch.

Wire connections at J8 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Smart Sensor Switches

Replace limit switch.

No Tilt Down.

Foot extension extended.

If foot extension is extended.

Move foot extension in or raise foot section.

Active Sensing Technology™ activated.

For obstruction on the top of column.

Remove object from the top of the column.

For obstruction under the foot section.

Remove object from under the foot section.

Position of chair. Refer to: Active Sensing Technology™

Activate Base Up and Foot Up, then try Tilt Down again.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Foot Extension switch.

Check wire connections at J6 on Machine Control PC Board and at switch.

Secure wire connections. Refer to: Fuses and Connections

Check Black and Red wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch.

Seat Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check two pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch(es).

Foot Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch(es).

Tilt Down limit switch.

Wire connections at J8 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Tilt Actuator / Limit Switches

Replace limit switch.

Tilt Down Overtravel limit switch.

Wire connections at J8 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Tilt Actuator / Limit Switches

Replace limit switch.

No Tilt Up or Tilt Down.

Active Sensing Technology™ activated.

For obstruction on the top of column.

Remove object from the top of the column.

For obstruction under the foot section.

Remove object from under the foot section.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Seat Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check two pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch(es).

Foot Smart Sensor Switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch(es).

Loose wire connections.

Wire connections at J6, J7 and J8 on Motor Control Hub PC Board.

Secure loose wire connections. Refer to: Fuses and Connections

Motor Control Hub PC Board fuse blown.

Test F2 fuse on Motor Control Hub PC Board.

Replace faulty fuse. Refer to: Fuses and Connections

Tilt Up and/or Down Overtravel limit switch.

Wire connections at J8 on Motor Control Hub PC Board and at limit switch(es).

Secure wire connections. Refer to: Fuses and Connections

Test limit switch(es). Refer to: Tilt Actuator / Limit Switches

Replace limit switch(es).

Motor runs, but chair does not move.

Motor coupler broken.

Motor coupler. Refer to: Tilt Actuator / Limit Switches

Replace motor coupler.

Tilt Up / Down noisy, grinding or squeaking.

Actuator threads dry.

Actuator threads.

Clean and lubricate tilt actuator threads. Refer to: Tilt Actuator / Limit Switches

Tilt Actuator.

Run tilt up and down, if squeaking or grinding continue check tilt actuator.

Replace tilt actuator.

Symptom

Probable Cause

Check

Solution

No Foot Up.

Treatment pan not in the stowed position.

If treatment pan is not completely pushed in.

Push treatment pan all the way in.

Active Sensing Technology™ activated.

For obstruction under the foot section.

Remove object from under the foot section.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Treatment Pan switch.

Wire connections at J6 on Machine Control PC Board and at switch.

Secure wire connections. Refer to: Fuses and Connections

Test switch. Refer to: Smart Sensor Switches

Replace Switch.

Foot Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch.

Foot Up limit switch.

Wire connections at J4 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Foot Actuator / Limit Switches

Replace limit switch.

Foot Up Overtravel limit switch.

Wire connections at J4 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Foot Actuator / Limit Switches

Replace limit switch.

No Foot Down.

Foot extension extended.

If foot extension is extended.

Move foot extension in.

Treatment pan not in the stowed position.

If treatment pan is not completely pushed in.

Push treatment pan all the way in.

Active Sensing Technology™ activated.

For obstruction under the foot section.

Remove object from under the foot section.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Foot Extension switch.

Check wire connections at J6 on Machine Control PC Board and at switch.

Secure wire connections. Refer to: Fuses and Connections

Check Black and Red wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch.

Treatment Pan switch.

Wire connections at J6 on Machine Control PC Board and at switch.

Secure wire connections. Refer to: Fuses and Connections

Test switch. Refer to: Smart Sensor Switches

Replace switch.

Foot Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switches. Refer to: Smart Sensor Switches

Replace switch.

Foot Down limit switch.

Wire connections at J4 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Foot Actuator / Limit Switches

Replace limit switch.

Foot Down Overtravel limit switch.

Wire connections at J4 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Foot Actuator / Limit Switches

Replace limit switch.

No Foot Up or Foot Down.

Treatment pan not in the stowed position.

If treatment pan is not completely pushed in.

Push treatment pan all the way in.

Active Sensing Technology™ activated.

For obstruction under the foot section.

Remove object from under the foot section.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Treatment Pan switch.

Wire connections at J6 on Machine Control PC Board and at switch.

Secure wire connections. Refer to: Fuses and Connections

Test switch. Refer to: Smart Sensor Switches

Replace switch.

Foot Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connection.

Test switches. Refer to: Smart Sensor Switches

Replace switch.

Loose wire connections.

Wire connections at J2, J3 and J4 on Motor Control Hub PC Board.

Secure wire connections. Refer to: Fuses and Connections

Motor Control Hub PC Board fuse blown.

Test F1 fuse on Motor Control Hub PC Board.

Replace faulty fuse. Refer to: Fuses and Connections

Foot Up and/or Down Overtravel limit switch.

Wire connections at J4 on Motor Control Hub PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Foot Actuator / Limit Switches

Replace limit switch.

Motor runs, but chair does not move.

Motor coupler broken.

Motor coupler. Refer to: Foot Actuator / Limit Switches

Replace motor coupler.

Foot Up / Down noisy, grinding or squeaking.

Actuator threads dry.

Actuator threads.

Clean and lubricate foot actuator threads. Refer to: Foot Actuator / Limit Switches

Foot Actuator.

Run foot up and down, if squeaking or grinding continue check foot actuator.

Replace foot actuator.

Symptom

Probable Cause

Check

Solution

“Home” function does not lower the chair to a height of 18 inches. Rotation Models 21.5 inches.

“Home” button pressed, then released.

If operator pressed and released “Home” button.

Press and hold “Home” button.

Foot extension extended.

If foot extension is extended.

Move foot extension in.

Active Sensing Technology™ activated.

For obstruction on the top of column.

Remove object from the top of the column.

For obstruction under foot section.

Remove object from under foot section.

Position of chair. Refer to: Active Sensing Technology™

Activate Tilt Up / Down and Back Up, then try Base Down again.

System malfunction.

Error code on Machine Control PC Board.

Refer to:Error Codes

Malfunctioning Wired Controls.

Wired Controls.

Refer to: Wired Controls Malfunctioning

Malfunctioning Wireless Controls.

Wireless Controls.

Refer to: Wireless Controls Malfunctioning

Foot Extension switch.

Wire connections at J6 on Machine Control PC Board and at switch.

Secure wire connections. Refer to: Fuses and Connections

Check Black and Red wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connections.

Test switch. Refer to: Smart Sensor Switches

Replace switch.

Seat Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check two pin inline connection next to Motor Control Hub PC Board.

Secure wire connection.

Test switches. Refer to: Smart Sensor Switches

Replace switch(es).

Foot Smart Sensor switches.

Wire connections at J18 on Machine Control PC Board and at switches.

Secure wire connections. Refer to: Fuses and Connections

Check Green and White wire connections at four pin inline connection next to Motor Control Hub PC Board.

Secure wire connection.

Test switches. Refer to: Smart Sensor Switches

Replace switch(es).

Base Down limit switch.

Wire connections at J5 on Power Supply PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Base Actuator / Limit Switches

Replace limit switch.

Base Up Overtravel limit switch.

Wire connections at J5 on Power Supply PC Board and at limit switch.

Secure wire connections. Refer to: Fuses and Connections

Test limit switch. Refer to: Base Actuator / Limit Switches

Replace limit switch.

Symptom

Probable Cause

Check

Solution

Rotational brake will not lock.

Brake pedal switch(s).

Unplug chair power cord. If base rotation locks, check brake pedal switch(s).

Replace sticking brake pedal switch(s). Refer to: Brake Pedal Switch Access.

Rotational brake mechanism

Unplug chair power cord. If base rotation does not lock, check mechanical brake components for any obstruction.

Clean mechanical brake components and remove any obstruction. Refer to: Brake, Electro-magnet Access.

Rotational brake will not unlock.

Loose wire connections.

Wire connections at J12 on Machine Control PC Board and at switch.

Secure wire connections.

Check Red and Black wire connections at J4 on Power Supply PC Board.

Secure wire connections.

Electro-magnet not energized.

If neither brake pedal works: Perform Screwdriver Test.

Refer to: Screwdriver Test.

Brake pedal switch(s)

If one Brake Pedal Switch works: Test switch.

Replace switch. Refer to: Brake Pedal Switch Access.

If neither pedal works.

Refer to: Rotational Brake PCB Input Test.

PC Board

Test Power Supply PC Board. Refer to: Rotational Brake PCB Input Test.

If necessary, replace Power Supply PC Board.

Base wobbles when locked and/or Grinding noise when base rotates.

Debris between upper and lower castings.

Inspect between upper and lower castings for debris.

Remove debris.

Loose hub screws

Check the four screws securing the upper and lower castings.

Tighten Hub Screws.

Damaged rotation bearings and/or brake disc.

Inspect rotation bearings and brake disc. Refer to: Brake, Electro-magnet Access.

Replace rotational base assembly.