LiftMaster RSL12U RSL12U Troubleshooting Guide Manual - Page 25

MODEL LA500U SYMPTOM: Operator does not have power. POWER CONTROL BOX TRANSFORMER BRIDGE RECTIFIER AC POWER SWITCH CONTROL BOARD Incoming Power 4 Check the transformer.* Check the transformer voltage going into the bridge rectifier (orange and yellow wires). The reading should be 24 Vac (+/- 10%). If not, replace the transformer. CONTROL BOARD 7 Check the control board. Try replacing the fuse on the control board. If that does not work, replace the control board. J15 Plug Transformer 5 Check the bridge rectifier.* Check the voltage coming out of the bridge rectifer (red and black wires).The reading should be 24 Vdc (+/- 10%). If not, replace the bridge rectifier. Bridge Rectifier Orange Yellow Blue EMI BOARD Brown Gray Purple 3 Black 120 240 Power Wiring Sockets (120 Vac factory Red default) Check the power wiring connector. Is it plugged into the correct socket? Black Red Black Red Battery 12V 7AH GROUND Green NEUTRAL White HOT 2 Battery 12V 7AH Black Check the AC power switch. Is it ON? Incoming Power 1 Check the incoming power.* Check breaker first, then check wiring coming into operator. The voltage should be 120 Vac or 240 Vac depending on the application. * 6 Check the batteries.* Check the battery connections. Make sure two 7AH batteries OR two 33AH batteries are connected in series. Check the voltage coming from each battery by disconnecting the battery from the operator. A fully charged battery should read 12.8 to 13.3 Vdc per battery. If not, replace the batteries. 24