Troubleshooting a broken light

Zblock

Zblock

Well-known member
Hey guys, I'll be looking around the internet for this but I'll ask here as well.

Yesterday one of my lights burnt out after being left on for about 15 min. I thought it was the lamp but a few minutes later I tried it again and it turned on briefly for about 5 seconds.

Today I replaced the lamp and the new bulb does the same thing. Burns really dim for a few seconds and fizzles out. When I switch the light off, it lights up briefly again.

I've also taken the head off and visually inspected all the wires and connections. Everything looks great.

I'm thinking I' melted a wire inside the chord or something messed up inside the switch. I don't have an ohm meter to check anything so does anyone have any suggestions.

Thanks,
 
When you say the lamp "fizzles out" do you mean it just goes dim?

If the lamp's element doesn't burn up and remains intact, it's probably the switch.

Turn the light on and tap on the switch, shake it, and flip it on and off.

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Is the bulb all the way in? A friend had a similar problem when going from spot to wide on an Arri 650 fresnel. Turns out the bulb was not seated properly and getting loose when flooding the light. If that's it, its a simple fix, but remember not to actually touch the bulb with bare hands.


Jason
 
Zblock said:
Hey guys, I'll be looking around the internet for this but I'll ask here as well.

Yesterday one of my lights burnt out after being left on for about 15 min. I thought it was the lamp but a few minutes later I tried it again and it turned on briefly for about 5 seconds.

Today I replaced the lamp and the new bulb does the same thing. Burns really dim for a few seconds and fizzles out. When I switch the light off, it lights up briefly again.

I've also taken the head off and visually inspected all the wires and connections. Everything looks great.

I'm thinking I' melted a wire inside the chord or something messed up inside the switch. I don't have an ohm meter to check anything so does anyone have any suggestions.

Thanks,
Click to expand...

What kind of light is it. If it is a direct connect to 120 VAC tungsten, could be loose wiring. For other types that have a ballast or other 'converter' circuitry, that could have failed, or is in the process of failing...

If the bulbs work in other lamp heads, then I'd say it's the lamp head/electronics.
 
Get yourself a multimeter and test the voltage and continuity of everything. You can get a cheap and decent one at harbor freight.
 
The lamp lights up for a split second and then rapidly dims. Upon flipping the switch off it does the same thing. I've re-seated the bulb a few times and taken apart the head of the light. All the wires look good in their contacts and things appear fine.

Could the switch have overheated and broke? I suppose I could take it apart and look inside.

If that yields no results I'll get the multimeter.

The light is a 650w redhead. It's pretty simple... plug-wire-switch-wire-head/electronics/bulb
 
Put your ear on the switch and listen for arcing. Other than the noise the switch makes for an instant when switching, the switch shouldn't make any noise. If you hear any odd noises coming from the switch, it could be a lose contact or a defective switch.

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Check the spring pressure on the porcelain lampholder ends. What sometimes happens is they have arced a bit and the little 'dimple' on the end of the spring section gets burnt away. While spring pressure is high - the lamp works, but the lack of the dimple means the very edge of the lamp contact is being used, not the centre, and they start to arc (with a quiet fizzle). The arc carries on, while the lamp goes out because the filament resistance means the arc is the easiest thing to 'power'. when you cut power, the arc, stops and then turning on starts the lamp again, only for it to go out again as the arc re-starts. Have a look closely at the spring contacts and the end of the lamp for signs of blackening.
 
It was the switch. I took it apart and couldn't find any visual problems but I beat it with a hammer and it turned on lol. So home depot sold me one with the same ratings that was half the size and I had to rig it into the original switch holder and get it steady. Lots of electrical tape but we're back in action.


I don't think it's a cowboy readhead. It's some company from Italy.
Thanks for the replies guys.
 
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