Midmark® Dental Halogen Light Troubleshooting Chart

Symptom Probable Cause Check Solution
Light does not illuminate, indicator lamp ON. Light is in AUTO-ON mode, and flex arm is positioned above horizontal. Check position of flex arm. Reposition flex arm. Inform user of proper operation.
Damaged / disconnected wiring. Check wiring from flex arm PC board to bulb socket in lighthead. Repair / replace wiring.
Faulty bulb. - Replace bulb.

Console / LR mounted lights only -

Light does not illuminate, indicator lamp OFF.

 No air supplied to pressure switch in power supply unit.

Turn Master ON / OFF Switch ON. Switch located on delivery unit.

 Refer to delivery system troubleshooting if necessary.
Facility circuit breaker. - Reset circuit breaker.
No power to power supply unit. - Connect power to power supply unit.
Power supply unit fuse(s) blown. Check fuses. Replace fuses.

Pressure switch malfunctioning.

Pressure switch located in power supply unit.

Perform continuity test on pressure switch.

With Master ON / OFF switch ON, there should be continuity between N.O. and COM terminals of pressure switch.

 Replace pressure switch.
Transformer in power supply unit malfunctioning.

Unplug light from power supply.

Turn Master switch ON.

Check voltage across secondary output leads of transformer. The voltage should be: 19.4 +2 VAC.

 Replace transformer if necessary.
Flex arm PC board is malfunctioning. Check for proper output voltages. Replace flex arm PC board.
Damaged / disconnected wiring. Check red and black wires from: transformer / flex arm PC board / lighthead. Repair / replace wiring.
Light touchpad is malfunctioning. Check continuity between terminals 1 and 6 of light touchpad while pressing power button on touchpad. If no continuity, replace touchpad.
Faulty connection to bulb socket. Clean bulb socket / secure connections. Replace bulb socket if necessary.

Ceiling / Track / Wall / Cabinet / Universal lights only -

Light does not illuminate, indicator lamp OFF.

 Facility circuit breaker. - Reset circuit breaker.

Transformer fuse blown. Fuse typically located inside cover on light mounting plate.

 Check fuse. Replace fuses.

Transformer malfunctioning. Transformer typically located inside cover on light mounting plate.

Unplug light from power supply.

Check voltage acrosss secondary output leads of transformer. The voltage should be: 19.4 +2 VAC.

 Replace transformer if necessary.
Flex arm PC board is malfunctioning. Check for proper output voltages. Replace flex arm PC board.
Damaged / disconnected wiring. Check red and black wires from: transformer / flex arm PC board / lighthead. Repair / replace wiring.
Light touchpad is malfunctioning. Check continuity between terminals 1 and 6 of light touchpad while pressing power button on touchpad. If no continuity, replace touchpad.
Faulty connection to bulb socket. Clean bulb socket / secure connections. Replace bulb socket if neccessary.
Symptom Probable Cause Check Solution
Light flashes (or goes out) when lighthead or flex arm is moved. Damaged / disconnected wiring. Check red and black wires from: transformer / flex arm PC board / lighthead. Repair / replace wiring.
Symptom Probable Cause Check Solution
Some functions work, some do not.

Touchpad malfunctioning.

Disconnect touchpad and use a meter to check continuity at terminals on back.

Touchpad Malfunctioning Diagram

Check continuity of touchpad.

For POWER switch: Check terminals 1 and 6 of light touchpad while pressing Power button on touchpad.

For COMPOSITE switch: Check terminals 1 and 4 of light touchpad while pressing Composite button on touchpad.

For INTENSITY switch: Check terminals 1 and 2 of light touchpad while pressing Intensity button on touchpad

 If no continuity, replace touchpad.

Damaged / disconnected wiring harness.

Use a jumper wire to short out two receptors on the touchpad harness connector.

Damaged/disconnected wiring harness diagram

Check continuity at the touchpad harness connector, coming from the flex arm PC board.

Check POWER: function by shorting receptors 1 and 6 of touchpad wire harness connector.

Check COMPOSITE: function by shorting receptors 1 and 4 of touchpad wire harness connector.

Check INTENSITY: function by shorting receptors 1 and 2 of touchpad wire harness connector.

 Repair / replace wiring.

Flex arm PC board is malfunctioning.

Remove the wire harness connector from J1 on the light PC Board. Use a jumper wire to short out two terminals.

 

PC Board diagram

Check PC Board functionality by shorting out two terminals on J1 on the PC Board in the flex arm.

DO THIS FIRST to turn power on. Check Light ON / OFF function by shorting terminals 2 and 6 at J1, on the PC Board.

Check COMPOSITE, lowest light setting: function by shorting receptors 2 and 5 at J1, on the PC Board.

Check INTENSITY function by shorting receptors 2 and 7 at J1, on the PC Board.

 Replace PC board in flex arm.
Symptom Probable Cause
Photo switch on flex arm PC board malfunctioning.

Select Auto-On function. Remove flex arm cover. Lower flex arm below horizontal so trigger is between two posts of photo switch (set point line).

Light should illuminate.
Symptom Probable Cause Check
Light beam out of focus. Check light pattern at focus depth between 21” to 39” (53 to 90 cm). Adjust light beam focus.
Symptom Probable Cause Check
Bulb malfunctioning. - Replace bulb.
Facility voltage is too low. Facility voltage should be: 115 VAC +11.5 V Correct voltage problem.
Flex arm PC board is malfunctioning. Check for proper output voltages. Replace flex arm PC board.
Transformer malfunctioning.

Unplug light from power supply.

Check voltage across secondary output leads of transformer. The voltage should be: 19.4 +2 VAC.

 Replace transformer if necessary.

Shield assembly is clouded.

This can be caused by cleaning solution.

 Inspect shield. Clean shield. Replace if necessary.
Symptom Probable Cause Check Solution
Light touchpad buttons work, but indicator lamp(s) do not illuminate. LEDs on touchpad burnt out.   Replace light touchpad.

Console / LR mounted lights only

Light stays ON when Master switch is turned OFF.

Pressure switch malfunctioning.

Pressure switch located in power supply unit.

Perform continuity test on pressure switch.

With Master ON / OFF switch OFF, there should not be continuity between N.O. and COM terminals of pressure switch.

 Replace pressure switch.
Symptom Probable Cause Check Solution
Light will not turn ON / OFF in Auto-On mode. Auto-On mode is out of adjustment.

Select Auto-On function. Remove flex arm cover. Lower flex arm below horizontal so trigger is between two posts of photo switch (set point line).

Light should illuminate.

 Adjust trigger to cross set point line earlier / later as necessary.
Symptom Probable Cause Check Solution
Lighthead does not rotate freely or drifts when released. Pivot joints out of adjustment. - Adjust pivot joint tension.
Flex arm drifts down on its own, or requires excessive force to lower. Flex arm spring tension out of adjustment. - Adjust flex arm spring tension.
One pivot joint will not rotate, or requires excessive force to move. Bearing in joint is dirty or damaged. Remove and clean bearing. Replace bearing if necessary.
Lighthead / arm(s) drift to one side. Light arm is not leveled properly. Place a level on vertical arm of light. Adjust light until level.
Flex arm rotates farther than it should. Stop pin is missing. Check for missing stop pin. Install stop pin.
Flex arm will not rotate thru its full range of motion. Stop washer installed incorrectly. Check orientation of stop washer. Reposition stop washer.