High-Pressure Sodium (dead) - ballast or cap?


Old 01-22-07, 09:27 AM
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Join Date: Mar 2006
Posts: 38
High-Pressure Sodium (dead) - ballast or cap?

I have a 70W HPS fixture that has worked fine for the past 15 years. I replaced the bulb once and the dawn/dusk sensor once. It recently stopped working completely - no flickering, no glowing, nothing. The bulb checks good in another fixture and I've wired around the dawn/dusk sensor - so it must be the capacitor or the ballast. The ballast shows about 3 ohms across any pair of wires so it doesn't appear to be burned out. I suspect the capacitor - is there a way to determine which is faulty? (The capacitor shows about 470K ohms across any two wires, but I know that DC resistance isn't much of a test for a capacitor.)
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Old 01-22-07, 09:59 AM
Join Date: Sep 2003
Location: Central New York State
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Have you determined that you are getting 120 volts to the fixture?
Old 01-22-07, 10:28 AM
Thread Starter
Join Date: Mar 2006
Posts: 38
HPS light - dead

Yes, I have 120v. And the little round device that I thought was a capacitor appears to be an igniter - I'm now even more suspicious that this is the problem. I've started looking around for a replacement ballast kit (ballast, cap, igniter) and have found several for $25-30.
Old 01-22-07, 02:20 PM
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Join Date: Apr 2003
Location: USA
Posts: 930
Try swapping the igniter with another working fixture. If that causes the dead fixture to work, replace the failed igniter. They do eventually fail, and they are cheaper than a new ballast. If that doesn't fix it, it is probably the ballast.
One question--Before the fixture failed, did the lamp "cycle" excessively due to a bad lamp? This will kill igniters in short order.
Good Luck!
Old 01-22-07, 05:33 PM
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Your light or a customer?

Yours' fiddle. A customers, replace all the guts, so your not back in a week with egg on your face.

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