115 VAC is supplied thru the two primary fuses (F1 and F2) to the transformer on the PC board. F4 fuse protects the transformer.

The transformer reduces the line voltage and supplies 14 VAC to the foot control.

When the Back Up function is activated, current (14 VAC) flows thru the Up function foot switch (N.O), then back to the PC board. Circuitry on the PC Board energizes the back relay. F5 fuse protects the back motor.

When the back relay is energized, the (2) Normally Open contacts of the relay close. When these contacts close, current (48 VDC) flows to the actuator motor.

When current flows to the actuator thru the Normally Open contacts of the relay, the actuator motor runs and raises the back section.

Actuator Motor runs until:

1.Foot control pedal is released.

2.Back Up limit switch is tripped.

3.26 second software time limit is reached.

4.Fuse(s) opens (blows). Primary, Back Motor, Transformer fuse.

If the Back Down limit switch is tripped (open), the Back Down function will not operate.

When the Back Down function is activated, current (14 VAC) flows thru the Down function foot switch (N.O.), then back to the PC Board.

When this voltage is applied, current (48 VDC) flows to the actuator motor thru the (2) Normally Closed contacts of the Back Up/Down relay. The relay does not energize.

When voltage flows to the actuator thru the Normally Closed contacts of the relay, the actuator motor runs and lowers the back section.

Actuator Motor runs until:

1.Foot control pedal is released.

2.Back Down limit switch is tripped.

3.26 second software time limit is reached.

4.Fuse(s) opens (blows). Primary, Back Motor, Transformer fuse

1.Loose wire connections, especially the Foot Control and Back Up/Down Limit Switches.

2.Main PC Board Fuses. Test fuses: F1, F2, F4, and F5. Refer to: Fuses

3.Perform Footswitch Test. Refer to:Foot Control

4.Back Actuator. To isolate the malfunction Refer to: Base/Back Actuator

5.Perform Back Relay Test. Refer to:Main PC Board

6.230 V models only: 230 VAC Transformer Fuses (2). Refer to: Fuses

1.Loose wire connections, especially the Foot Control and Back Down Limit Switches.

2.Back Down Limit Switch. Perform Limit Switch Test. Refer to:Limit Switches

3.Perform Footswitch Test. Refer to:Foot Control

4.Perform Back Relay Test. Refer to:Main PC Board

1.Loose wire connections, especially the Foot Control and Back Up Limit Switches.

2.Back Up Limit Switch. Perform Limit Switch Test. Refer to: Limit Switches

3.Perform Footswitch Test. Refer to:Foot Control

4.Perform Back Relay Test. Refer to: Main PC Board

1.Run back section up and unplug power cord. If drifting stops, perform Footswitch test. If drifting continues, check Back Actuator.

2.Perform Footswitch Test. Refer to:Foot Control

3.Back Actuator. To isolate the malfunction, Refer to:Base/Back Actuator.

1.Wire Connections reversed. Check Foot Control and Base Actuator motor connections.

2.Replace Main PC Board. Refer to:Main PC Board

1.Clean and lubricate back actuator threads. Recommended lubricant: Lithium Grease. Unscrew the shaft cover to access actuator threads.

2.Replace Back Actuator. Refer to: Base/Back Actuator

1.Did patient exceed 400 lb. weight limit? Inform staff that max patient weight is 400 lbs.

2.Low voltage to table.