LiftMaster BG770 BG790 Manual - Page 14
Troubleshooting
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TROUBLESHOOTING When troubleshooting, one of the first things to do is try to isolate the problem area. The four (4) main areas to check out are: • Power • Accessories • Operator's Primary Voltage • Operator's Low Voltage POWER Always use extreme caution! Some possible symptoms of power problems include: • The obvious one is - the operator will not run. • The operator runs slow. • Circuit breakers or fuses keep tripping. • Motor overload keeps tripping. • Operator starts but then stops. Using a volt-ohmmeter, take a voltage reading at the control transformer's primary terminals. You should get a reading as follows: Nominal Voltage 120V 230V 460V Minimum 108 207 414 Maximum 132 253 506 ACCESSORIES Add-on accessories can create many of the problems that are credited to the operator. Many applications have more than one accessory item attached to the operator and some of these items even draw their power from the operator. Some of the symptoms that can show up because of accessories: • The operator will not close. • The operator will not open. The operator will not run. • The operator begins to run, then stops or reverses. Whenever the problem is thought to be an accessory and there are more than one connected to the operator, always disconnect one accessory at a time and then test the system. This will hopefully isolate which item is causing the problem. If an accessory item is being used as an access control device (used to open or close), falls in the closed position or sends out a continuous signal. The operator will hold the gate in one position until the signal from the accessory is removed. In some applications, the gate may begin to move then either stop or stop and reverse within a couple of seconds. This can be caused by an external obstruction device that has failed. If there are many accessories attached to and powered by the operator, there may be too much current draw for the operator's control transformer. This operator can only supply approximately 2 amps @ 24Vac. Double check all accessories for their current requirements. If you get a reading that does not fall into the minimum/maximum area, then check out your main power supply. Also, make sure that the operator was ordered with the proper voltage and phase. Another item to check is the wire run from the power supply to the operator. Double check the gauge of the wire versus the distance. If the voltage reading is okay from 1A, then take the same voltage reading with the operator running. If voltage drops below the minimum with this reading, then there could be an excessive current draw somewhere, or a wire AWG is too small. In some cases, power drops can occur at only specific times during the day or night. This can be caused by increased power demands in a general area at a specific time-particularly areas undergoing rapid growth. 14