Mystery Strobe

D

dlsmith

Pre-takeoff checklist
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Oct 6, 2014
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Dylan Smith
Hey all, the strobe on my fathers 172 quit on him the other day. Just a blown bulb, but we can't find one to match it. There's no part number. I'm thinking we're probably going to be stuck replacing the assembly, but I'm hoping someone will know where to get one. Here's a pic



Thanks!
 
Haven't seen those wire trap things since I was a kid. Never knew they were used on airplanes.
 
Strobes don't blow... They arc through gas in a sealed tube.


Have you put a multimeter on it? Continuity across the resistor?
 
I'm not sure what he's done. Something about the black end of the bulb looks off to me, but I've never messed with stobes.
 
this is a Flightstrobe 4400.

It's cheesy but they work reasonably well. Parts are available through Aircraft Spruce.
 
this is a Flightstrobe 4400.

It's cheesy but they work reasonably well. Parts are available through Aircraft Spruce.

If the bulb replacement doesn't bring it back to life you have a problem with either the trigger circuit or a burnt capacitor. Capacitor failure is indicated by a burned hole or broken X in the end of the large blue capacitor.
 
dlsmith said:
Hey all, the strobe on my fathers 172 quit on him the other day. Just a blown bulb,
Click to expand...


Why do you believe that it is blown (whatever that means) bulb. I see you are a student, probably A&P. More better you get your education on this so that you can help other folks in the future.

JIm
 
weirdjim said:
Why do you believe that it is blown (whatever that means) bulb. I see you are a student, probably A&P. More better you get your education on this so that you can help other folks in the future.

JIm
Click to expand...
Actually I'm a pilot, not A&P. But I've always been one to dig into things, provided they fall into the "preventative maintenance" category :D

I saw the blackened section of the bulb and thought that may very well be the problem. But, I've never dealt with strobes, this is the first airplane we've had equipped with anything other than a normal beacon, which is why I consulted those more knowledgeable (y'all).
 
dlsmith said:
I saw the blackened section of the bulb and thought that may very well be the problem. But, I've never dealt with strobes, this is the first airplane we've had equipped with anything other than a normal beacon, which is why I consulted those more knowledgeable (y'all).
Click to expand...

Back in the vacuum tube days, drug stores made a freakin' FORTUNE with their tube testers and convincing people that the silver coating on the inside of the bulb was from wearout. It was actually from the process of electrically removing the last vestage of the gas inside the tube after it was vacuum pumped and sealed. THe more silver coating, the more the tube had been really evacuated.

THe black end looks to me like a carbon cathode that will stand the heat of "sun in a bottle" operation. I could be wrong and I don't have a flash tube here that I can look inside of. When Mouser stopped carrying them about fifteen years ago I stopped using them in projects.

Jim
 
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