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View Full Version : Help with MH capacitor testing.


racer69
04/19/2006, 01:40 PM
Can someone give me some step by step instructions on how to test a 250w hpi mh capacitor. I have it out of the ballast box, and have a multitester(not good with it but will try). Russ, you know how to do this don't you?

Crit21
04/19/2006, 01:58 PM
I was an electronics tech years ago. MH capacitors can definitely riun your day if you happen to complete the circuit while it's charged. I'd bring it to the meeting Saturday so Russ can test it safely.

Do you have a multimeter?

Crit21
04/19/2006, 02:12 PM
As large as MH caps are, even a multimeter may not provide an accurate assessment. I've seen caps that look good on a multimeter that breakdown under higer voltage. Regardless, you should isolate (remove) the cap so you can test it with an ohmmeter. When the leads are connected to the correct ends you'll see the resistance increase to a very high value as the cap charges. Reversing the connections will result in a rapid discharge.

Crit21
04/19/2006, 02:15 PM
The best way to really test a capacitor is to substitute a known good one. Do you have one lying around?

racer69
04/19/2006, 03:33 PM
No, but I am ordering on today from Hellolights.com.

Deuce67
04/19/2006, 04:52 PM
Todd, I have no way of testing a capacitor. To tell you the truth, I never tested one. One thing about about HQI ballast is they are not popular except in the reefing world. Heck, its cheaper for me to buy online than what my suppliers would charge me. You can bring it down and we can take a look at it. PM me with the info on the capacitor and Ill see if one of my suppliers have one.

racer69
04/19/2006, 08:35 PM
Russ, I already ordered one from hellolights.com that I will keep around as a backup. After I got home from work tonight I took out the bulb and it was burnt out. It is 2-1/2 months old. It is a Hamilton 14k 250DE that I got from Mr. Aqua. There is a one year warrenty on this bulb so he should get me another one.

COreefer
04/20/2006, 10:16 PM
Are we talking about the Flux Capacitor here or what???

Crit21
04/21/2006, 06:50 AM
Most people refer to it as the starter in the MH ballast. The capacitor stores a charge, then suddenly releases the charge to start the bulb.

Deuce67
04/21/2006, 08:08 AM
<a href=showthread.php?s=&postid=7218120#post7218120 target=_blank>Originally posted</a> by COreefer
Are we talking about the Flux Capacitor here or what???

Yup. We found out a way to generate 1.21 gigawatt of electricity. Just searching for a Delorean that can actually do 88 mph.:D

calvin415
04/21/2006, 08:15 AM
<a href=showthread.php?s=&postid=7219496#post7219496 target=_blank>Originally posted</a> by Deuce67
Yup. We found out a way to generate 1.21 gigawatt of electricity. Just searching for a Delorean that can actually do 88 mph.:D

LOL!!!! 1.21 Gigawatts!!!!!

Crit21
04/21/2006, 10:30 AM
1.21 GIGAWATTS!!!!!!

Crit21
05/04/2006, 11:03 PM
Racer, what's the latest?