Strobes Only Fire Once When the Engine is Running

[nucleus]

I have been attempting to troubleshoot my strobe problem, and thought I would access the VAF collective wisdom.

My strobes work fine with the engine stopped. Once the engine is running, they only fire once when turned on, then stop.

I have switched strobe boxes, and switched circuits, and cleaned up the ground connections, with no change. Voltmeter at the wingtip shows 12.6 volts when the engine is stopped. Haven't tested volts at the wingtip yet with the engine running. Voltmeter on the panel says 14 with the engine running. Ground resistance is .04 Ohms, which is the same as connecting the two test leads together.

It has been suggested to me that I try a capacitor on the positive lead to the strobe box.

Suggestions?

Hans

[rocketbob]

Undo the strobe assembly at the wingtip, leaving it hanging, and fire up the airplane. I've seen weird grounding issues with the bulbs do the same thing.

[LifeofReiley]

Maybe your ground tab on the fixture has an issue... 2 cents worth...

[D-Dubya]

That's a head-scratcher, Dr. H.

Try some different combinations to see if you can narrow down the circuit that's the culprit. Does it do it if your engine switches are all "on" but you haven't started the engine yet? What about isolating one ignition and then the other and seeing if the strobes work? Can you get a helper to wiggle the wires with the engine running and then not running to see what happens? Not sure if those make sense, but maybe it will help to zero in on the issue.

I'm kind of leaning toward what the others are saying about grounds. I've seen them cause all kinds of strange problems that don't make apparent sense--both at work and on planes & cars.

Let us know what you find.