The Care and Feeding of Strobe Lights

The Care and Feeding of Strobe Lights by Tom Fredericks November 1999 Astrobe light is a capacitive discharge, high energy device, often used to meet aircraft anti-collision requirements. In general, an inverter circuit converts...


The Care and Feeding of Strobe Lights

by Tom Fredericks


Astrobe light is a capacitive discharge, high energy device, often used to meet aircraft anti-collision requirements. In general, an inverter circuit converts DC input voltage into a high level output voltage of between 350 to 550 volts. This voltage is then applied to a xenon gas flash tube. In addition, a trigger voltage is pulsed to the glass envelope of the flash tube.

The trigger pulse causes the xenon gas to ionize, which allows the high voltage to conduct. This results in the high intensity flash of the flash tube. There are two basic types of aircraft strobes. A self-contained strobe consisting of a lens, flash tube and electronic power supply all housed in a single unit or a remote strobe consisting of a power supply, a three conductor cable and a remote lens and flash tube assembly. In both cases, the lens, flash tube and electronic power supply come in various sizes and power levels to fit a number of different applications.

ImageTroubleshooting a self-contained strobe unit
The first step in troubleshooting a self-contained strobe, that does not flash, is to check the circuit breaker in the aircraft. If the breaker is okay, then measure the voltage at the input to the strobe. Note that some early strobes emitted an audible sound when turned on. This was often used to determine that voltage was present, however, a meter is a more reliable method of checking.

If power is present at the unit, visually inspect the flash tube. Replace it if it is blackened or cracked. If the strobe flash tube is okay, then the power supply must be defective and the unit must be repaired or replaced.

For a self-contained strobe unit that operates irregularly, the first step is to check for a faulty power connection at the breaker or strobe unit. Make sure that the unit has a good ground connection all the way back to the aircraft power source. If the connections are okay, then the power supply must be defective and the unit must be repaired or replaced.

Troubleshooting a unit with a single remote strobe
Troubleshooting a single remote strobe unit is similar to a self-contained unit, with one obvious difference, the interconnect cable. For a strobe that does not flash, the first step again, is to check the circuit breaker in the aircraft. If the breaker is okay, then again, measure the voltage at the input to the power supply.

If power is present at the power supply, visually inspect the flash tube. Replace it if it is blackened or cracked. If the flash tube appears to be okay, check the interconnect cable. One way to isolate the cable is to connect another cable and flash tube assembly at the power supply. If this works, then the power supply is good and the problem is with the remote flash tube assembly or the cable. Replace the flash tube assembly. If the unit still does not work, then replace the cable, as a last resort. If a flash tube darkens and fails within a short period of time, such as 30 minutes to a few hours, there may be a wiring problem. Check all three wires, at both ends of the cable, for proper connections.

Troubleshooting a unit with multiple strobes
Troubleshooting a power supply with multiple remote strobes is often easier than a single remote unit, since the remote flash tube assemblies can be swapped to isolate problems. In a case where neither strobe flashes, begin again with a circuit breaker and power supply voltage check.

If the power is okay and since neither of the strobes are flashing, the problem is most likely a defective power supply. Repair or replace it.

If one strobe is not flashing, swap the strobe connections at the supply to determine whether the problem is with the remote strobe assembly or the output section of the power supply. If the flash tube appears to be okay, check the interconnect cable. As a last resort, replace the interconnect cable.Image

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