Turn on all aircraft strobe lights to determine which one is malfunctioning.
Turn all aircraft strobes off. Wait 10 minutes for the power supply capacitors to discharge before you begin to troubleshoot the strobe problem.
Remove the cover and lens assembly of the non-functioning strobe with a Philips screwdriver. The strobe lens is made of glass and will break if dropped.
Inspect the strobe tube to ensure that it is not cracked. Confirm that the trigger wire, which is spirally wrapped around the tube, is intact.
Remove the faulty strobe tube by unplugging the three-pin connector. Place the tube in a safe location. Handle strobe tubes with gloved hands so you do not transfer your hands' body oils to the tubes.
Plug a known functioning strobe tube into the three-pin connector. A functioning strobe indicates that the original strobe tube is faulty. A non-functioning strobe may indicate a faulty power supply.
Locate your aircraft's strobe power supply. Consult the aircraft's maintenance manual to find the location of the strobe power supply or supplies. Some aircraft have a power supply in each wing, while others have a dual-channel supply located in the fuselage.
Access the power supply by removing all necessary panels.
Turn on the aircraft strobes. Ask an assistant to turn the strobes on. Listen for a high-pitched whine coming from the power supply. This sound indicates that the power supply is functional.
Measure for the correct input voltage. Use a volt-ohm meter set to volts DC. Measure the voltage between the first and second pins. The voltage will be either 12 or 24 volts, depending on the aircraft. Turn off the aircraft strobes.
Disconnect the three-pin output connector from the power supply.
Connect a known functional strobe tube into the power supply's output jack. Turn on the aircraft strobes. The power supply is faulty if the strobe does not function. If the strobe does function, the fault is in the aircraft harness. The problem is most likely a broken wire. In many cases, it is faster to run a new harness out to the wingtip than to locate the faulty wire.
Turn the aircraft strobes off. Reassemble access panels and lens cover assemblies you previously removed to troubleshoot the faulty strobe.
