OSMAC RDR®: Heads Pulsing On/Off
LESSON SUMMARY: This lesson is designed to assist the user in troubleshooting what could cause sprinkler heads to pulse on and off in an OSMAC® RDR system.
Special Tools Needed: Flathead Screwdriver
⚠ CAUTION: THIS LESSON MAY INCLUDE INSTRUCTIONS TO TEST HAZARDOUS VOLTAGES (120V-240V) THAT CAN CAUSE SERIOUS INJURY OR DEATH. IT IS RECOMMENDED THAT A LICENSED ELECTRICIAN BE CONTRACTED TO PERFORM SUCH TESTS.
🛑 STOP: ALWAYS TURN OFF THE POWER TO THE SATELLITE BEFORE REMOVING OR INSTALLING COMPONENTS.
If your sprinkler heads are pulsing on and off, the Receiver Decoder Module or one or more 8-Station TRIAC Boards in the corresponding satellite may be damaged. Follow the guided steps below to determine which component(s) require replacement.
Testing the Receiver/Decoder Module:
The Receiver/Decoder Module should be the first component tested for functionality. The Receiver/Decoder Module in an OSMAC RDR® control system is located in the furthest position in the right-hand side of the satellite box enclosure. To test the Receiver/Decoder Module, proceed with the following steps:
Start by powering off the satellite.
Next, disconnect the three Power Transformer wires from the Receiver/Decoder Module. The three Power Transformer wires are black, orange and red.
Unplug the TRIAC Board in the first position from the Receiver/Decoder Module.
Proceed to unscrew and disconnect all wires from the 5-position screw terminal in the lower right-hand corner of the Receiver/Decoder Module.
Remove the Receiver/Decoder Module from the satellite box enclosure and take it to a known-working location to test.
*Note: Prior to installing the Receiver/Decoder Module at a known-working satellite location, be sure to power off the satellite at the known-working satellite location. Power to the satellite should always be off before installing or removing components.
Once the Receiver/Decoder Module is installed in a known-working satellite location, if the sprinkler heads corresponding to the known-working satellite location begin to pulse on and off, the Receiver/Decoder Module is damaged and should be replaced.
If the sprinkler heads corresponding to the known-working satellite location do not pulse on and off when the Receiver/Decoder Module is installed, the Receiver/Decoder Module is functioning properly and can be reinstalled at the original satellite location.
If the sprinkler heads corresponding to the known-working satellite location do not pulse on and off when the Receiver/Decoder Module is installed, further troubleshooting at the original satellite location is required.
Replacement Receiver/Decoder Modules can be purchased here.
Testing the TRIAC Boards:
The TRIAC Boards in an OSMAC RDR® controller are located in the satellite box enclosure to the left of the Receiver/Decoder Module. Each TRIAC Board runs 8 stations. An OSMAC RDR® controller can house up to six TRIAC Boards and can run up to 48 stations. To test the TRIAC Boards, proceed with the following steps:
*Note: In order to accurately test the functionality of the TRIAC Boards, a known-working Receiver/Decoder Module should be installed in the satellite.
Begin by testing the TRIAC Boards individually.
Start by powering off the satellite.
Next, unplug and remove all TRIAC Boards from the satellite, with the exception of the TRIAC Board located in the first position. The TRIAC Board in the first position is located directly to the left of the Receiver/Decoder Module and runs stations 1-8.
Power the satellite back on.
Proceed to key a command on your Handheld Irrigation Radio to turn on a station.
If the station activates properly and no pulsing sprinkler heads are observed, the TRIAC Board in the first position is functioning properly.
If the sprinkler heads pulse when a command to turn stations is entered in your Handheld Irrigation Radio, the TRIAC Board installed in the first position is damaged and should be replaced.
The remaining TRIAC Boards should be tested individually by installing them in the first position of the satellite, making sure after each installation that stations activate properly when a command is entered on your Handheld Irrigation Radio.
*Note: Prior to removing and installing each TRIAC Board, be sure to power off the satellite at the known-working satellite location. Power to the satellite should always be off before installing or removing components.
After all TRIAC Boards have been individually tested, you may reinstall all known-working TRIAC Boards back into the satellite.
Replacement TRIAC Boards can be purchased here.
*Note: While uncommon, it is possible that a failing Power Transformer can also cause sprinkler heads to pulse on and off. The AC Voltage for the Power Transformer should be measured.
Instructions on how to test the voltage for a Power Transformer can be found here.
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