MH troubleshooting

[BCWolfen]

So a friend of mine managed to pick up a 250W MH ballast, a mogul socket and 2x250W 10K MH bulbs for free. He works for the school district and they have been swapping out their old MH lighting for more energy efficient stuff. We're having some trouble and I hope to get some insight as to what it might be. These components were ripped out ungraciously by the contractors and just dumped into a storage closet where they will rot until the school is torn down. (isn't our system wonderful?) Anyway I think it may be the ballast and he's going to grab the other 4 that are there on Monday to try. but heres what we got.

Did a quick connection just to see if we had power and got the bulb to fire. I only left it on for about 1 second as all connections were temporary. We assumed all would be good. Upon building our box (out of an old computer power supply) and hooking it up with quick disconnects and an on/off switch we fired it up for real.
The bulb fired immediately, then it started to flicker inside the little inner bulb. Slowly at first then faster and faster. Then suddenly it went out. A few seconds later a small blue glow appeared. Then it fired again and repeated the process.

Thinking it may be a bad bulb we tried the other. Same results. Thinking they may both be bad due to being tossed around I tried one of my 250W. Same thing.

To rule out bulbs I tried all 3 in my lights and they fired perfectly.
To rule out the longer cables, quick disconnects and switch I rewired everything direct and plugged t in. Same thing.
I even went as far as to clean all the wires (they had a bit of corrosion on them) Same thing.

So now I'm pretty sure its a bad ballast but wanted to know if this seemed a typical result of a dead ballast.

lmk
Thanks

[reeferaddict]

Hey Gerald,

I bought a brand new PFO ballast and one of them gave me the exact same thing... it's the capacitor, the cylinder shaped thing wired between the ballast and the final output to the bulb. I think they can be had for between $8 - $12 at an electrical supply outlet or electronics shop.

[Bryan]

What position were you burning the bulb at, horizontal, vertical, base up?.

[StirCrazy]

are you sure they are MH ballasts and not HPS ballast? also if you know thw manufacture and model number of the ballasts let me know.

Steve

[Invigor]

Hey Gerald,

I bought a brand new PFO ballast and one of them gave me the exact same thing... it's the capacitor, the cylinder shaped thing wired between the ballast and the final output to the bulb. I think they can be had for between $8 - $12 at an electrical supply outlet or electronics shop.

same thing happened to me, although it was just because I had a few things wired improperly. but it was the capacitor that was connecting incorrectly.

[BCWolfen]

What position were you burning the bulb at, horizontal, vertical, base up?.
We were testing them horizontally, but it also did run them hanging in their vertical position. Same results.

are you sure they are MH ballasts and not HPS ballast? also if you know thw manufacture and model number of the ballasts let me know.

We are sure they are MH. Although the ballast no longer has any information sheet on it. There was another of the same kind (though it had broken wires) that had a MH label. We also looked up the model number on the capacitor and it listed the ballast and Cap as being for a 250W MH system.

We stopped into a local Hydroponics today and he seemed to think it was the cap as well, but didn't have any. Aaron has gone to home depot to see if he can get one there and we'll try again later tonight.

Worst case we have to wait until tomorrow and we'll have 5 others to work with and see what we can get to work. LOL

[Bryan]

Here is a good site on HID ballasts.

http://www.fortunecity.com/meltingpot/cambie/38/id33.htm


From their FAQ file.

How do you know when the capacitor has gone bad?

The lamp will not normally work if the ballast circuit is a CW or CWA.
Testing is the only way to know when the capacitor has gone bad on HX-HPF and R ballast circuits. On HX-HPF and R the amp draw will almost double when the capacitor fails.