OSMAC RDR: Testing Switch & Surge Board
LESSON SUMMARY: This lesson is designed to assist the user in troubleshooting Switch & Surge Boards and being able to identify which Switch & Surge Boards are working and which Switch & Surge Boards should be replaced.
Special Tools Needed: Digital Multimeter, Phillips 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 you are unable to run stations by entering a command on your Handheld Irrigation Radio or if you are unable to toggle on an individual station manually, one or more Switch & Surge Boards is likely damaged. Follow the guided steps below to determine which component(s) require replacement.
Shorted Switch & Surge Board:
If you suspect that one or more of your Switch & Surge Boards have been shorted, proceed to test each Switch and Surge Board using the following steps:
The Switch & Surge Boards are mounted in the satellite enclosure below the Receiver/Decoder Module and below the 8-Station TRIAC Boards.
Start by powering off the satellite.
Next, set all switches on the Switch & Surge Board to the OFF position.
Using a digital multimeter on the resistance setting or continuity setting with an audible beep, place one probe of the digital multimeter on the copper Ground connection, located below the 8-position screw terminal, while using the second probe to measure each individual station on the Switch & Surge Board.
To measure each individual station, hold the second probe of the multimeter on the screw containing the station wire. The screws containing the station wires are located on the 8-position screw terminal located on the left side of the Switch & Surge Board.
Proceed to test each station, noting the readings displayed on your digital multimeter.
If using a digital multimeter on the resistance setting, the display should read Over Limit or “OL” if the station is not shorted. *Note: Certain multimeters will display a reading of “1” instead of Over Limit (“OL”); this is considered acceptable.
If using a digital multimeter on the continuity setting, no audible beep should be heard if the station is not shorted.
During the course of testing, if your digital multimeter displays a reading other than Over Limit (“OL”) on the resistance setting, or if an audible beep is heard on the continuity setting, the Switch & Surge Board is damaged and should be replaced.
Replacement Switch & Surge Boards can be purchased here.
Stations Not Turning On After Entering Command On Handheld Irrigation Radio:
If you are unable to run stations by entering a command on your Handheld Irrigation Radio, one or more of your Switch & Surge boards could be damaged. Proceed to test each Switch and Surge Board using the following steps:
Start by powering off the satellite.
Next, set all switches on the Switch & Surge Board to the AUTO position.
Use a digital multimeter on the resistance setting or continuity setting with an audible beep. If using the resistance setting, touch the two multimeter probes together and note the reading on the display; it should be 0 or very close to 0. *Note: Different multimeters will vary slightly.
Proceed to test each station by placing one probe of your digital multimeter on the screw terminal containing the station wire on the Switch & Surge Board and place the other probe on the corresponding screw terminal on the 8-Station TRIAC Board. *Example: If testing station one, place one probe on the screw terminal on the Switch & Surge Board labeled “1” and place the other probe on the screw terminal on the 8-Station TRIAC Board labeled “1”.
If using a digital multimeter on the resistance setting, each working station on the Switch & Surge Board will display a reading close to the reading that was displayed when the two probes were touched together: 0 or very close to 0.
If using a digital multimeter on the continuity setting, each working station on the Switch & Surge Board will create an audible beep.
If the digital multimeter reads Over Limit “OL” on the resistance setting, or no audible beep is heard on the continuity setting, the Switch & Surge Board or the Satellite Wiring Harness is damaged and should be replaced.
Wiring Harness Troubleshooting:
The Wiring Harness is the set of wires that connects the Switch & Surge Boards to the 8-Station TRIAC Boards. To test the Wiring Harness, proceed with the following steps:
Start by powering off the satellite.
Next, unplug the Wiring Harness from the Switch & Surge Board.
Unscrew all station wires from the Switch & Surge Board.
Using a Phillips screwdriver, unscrew the mounting screws used to hold the Switch & Surge Board in place and remove the Switch & Surge Board from the satellite.
Proceed to install a new or known-working Switch & Surge Board, making sure to reconnect all station wires.
Plug the Wiring Harness into the new or known-working Switch & Surge Board.
Using the steps outlined under the section titled “Stations Not Turning On From Receiver/Decoder Module”, proceed to test each station.
If the digital multimeter reads Over Limit (“OL”) on the resistance setting, or no audible beep is heard on the continuity setting for any individual station, the Wiring Harness is damaged and should be replaced.
Replacement Switch & Surge Boards (with Wiring Harness) can be purchased here.
Manual ON Check:
To test the Manual function of the Switch & Surge Board, proceed with the following steps:
Start by powering off the satellite.
Next, check that the 3A Fuse on the Switch & Surge Board is working. *Note: Visually inspecting the fuse is never a trustworth method to determine the failure or functionality of the fuse.
Remove the 3A Fuse from the fuse holders on the Switch & Surge Board.
Using a digital multimeter on the resistance setting or continuity setting with an audible beep. If using the resistance setting, touch the two multimeter probes together and note the reading on the display; it should be 0 or very close to 0. *Note: Different multimeters will vary slightly.
Proceed to place one probe on each end of the fuse.
If using a digital multimeter on the resistance setting, a working fuse will display a reading close to the reading that was displayed when the two probes were touched together: 0 or very close to 0.
If using a digital multimeter on the continuity setting, a working fuse will create an audible beep.
If the digital multimeter reads Over Limit (“OL”) on the resistance setting, or not audible beep is heard on the continuity setting, the fuse is damaged and should be replaced.
If the fuse has been tested and is known to be working properly, you may reinstall it on the Switch & Surge Board.
Replacement 3-AMP Fuses can be purchased here.
Once you have tested the 3A Fuse, proceed to set all switches on the Switch & Surge Board to the ON position.
Next, using a digital multimeter on the resistance setting or continuity setting with an audible beep, place one probe of the multimeter on the end of the fuse closest to the Ground connection (shown below) and one probe on the screw terminal containing the station wire, starting with position 1.
If using a digital multimeter on the resistance setting, each working station on the Switch & Surge Board will display a reading close to the reading that was displayed when the two probes were touched together: 0 or very close to 0.
If using a digital multimeter on the continuity setting, each working station on the Switch & Surge Board will create an audible beep.
If the digital multimeter reads Over Limit “OL” on the resistance setting, or no audible beep is heard on the continuity setting, the Switch & Surge Board is damaged and should be replaced.
Proceed to test each station using the steps outlined above.
Replacement Switch & Surge Boards can be purchased here.
*Note: If the 3-AMP fuse on the Switch & Surge Board blows when a station is manually switched to the ON position, complete the testing steps under the section of this article titled “Shorted Switch & Surge Board” (above), and check solenoid resistance.
An in-depth lesson on how to check solenoid resistance can be found here.
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