LiftMaster JHDC Installation Manual - English French Spanish - Page 47

Troubleshooting (continued) Symptom LCD wall control is off or not functioning (display shows nothing or is unlit, and wall control is unresponsive) (continued) Possible Causes Diagnosis Resolution Multiple LCD wall controls wired to a single operator. Only one LCD wall control is supported per operator. Check that only one is connected to the WALL CTRL terminals on the powerhead main board. Disconnect any additional LCD wall controls and wire just one LCD wall control. If additional control stations are desired, use the SBC or OPEN, CLOSE, and STOP terminals instead. Wall control is wired to incorrect terminals on the powerhead main board. Confirm that wall control wiring is run to the WALL CTRL terminals on the powerhead main board. Move wall control wiring to the WALL CTRL terminals No power to powerhead main board Verify MAIN PWR LED is lit on the mainboard. If if it unlit, main board may not have power. Follow troubleshooting for symptom 'Powerhead main board is off' Wall control circuit Test for wall control short circuit: shorted Power cycle the operator. Check WALL CTRL LED on powerhead main board. Turn off AC power and disconnect batteries (if present). Remove wall control wiring from main board terminals. Restore batteries and AC power. If LED is unlit, a short circuit is detected on the WALL CTRL terminals by the main board and the wall control is disabled. If WALL CTRL LED remains unlit, short circuit may be internal to main board. Replace main board. If WALL CTRL LED is blinking, short is in wall control wiring or wall control. Reconnect wiring to main board. Disconnect wall control from wiring. Repeat test. If WALL CTRL LED is blinking, short is in wall control. Replace wall control. If WALL CTRL LED is off, short is in wiring. Check wiring and correct the issue. Bad connection between wiring and wall control Visually inspect the wiring connections to the wall control screw terminals. Wires should be sandwiched between the screw and the exposed metallic pads on the circuit board. Ensure insulated part of wire is not caught between screw and circuit board. Correct any issues noted during inspection No voltage output from powerhead main board WALL CTRL terminals Verify main board WALL CTRL terminals: Disconnect wall control wires. Measure DC voltage at WALL CTRL terminals. If voltage is absent or out of range, turn off power to operator and disconnect batteries if present. Wait 30 seconds and then reconnect batteries and reapply AC power. Voltage should be between 11 and If fault persists, replace main board 13V DC. 47