It's the ignitor!

The ignitor is only usefull for the HPS not the MH, that's actually one of the tests to check if the ignitor in a HPS setup is bad, put a MH bulb in, if it works the igniter is bad if it doesn't it's something else.

Good post andyboy, I was about to state the same thing. A hps bulb needs an ignitor, the mh doesn't.
If the ballast was sold as a switchable one, then either there's a switch on it, or you have to open it up and route the wiring through the ignitor. Most electronic ballasts will automatically switch the ignitor depending on what type of bulb is being used. If the wiring already goes through the ignitor then you need a new ignitor.
It says a lot for the caliber of people who work in hydro shops that they didn't tell you this.

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Originally Posted by ceestyle
Don't be a martyr wasting $100 or more on CFLs to prove they're inferior for flowering pot.

Couldn't agree with that last line more Hairy Bob... I will drop in the ignitor when i get home and give it a shot. OK just so i get this clear... The Ballast I have has the wiring routed through the ignitor.. BUT the MH bulb does not need the ignitor to light it up whereas the HPS DOES need the ignitor... but is it ok to have the ballast wired up this way (thru the ignitor) permanently to run both MH and HPS? Thanks so much for the help...

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5,4,3,2,1 blunts pass off! Pick a planet, roll it, toke it, smoke it and we blast off...

If it's a digi ballast with switching capacity then it should be fine. Even if you have a normal magnetic ballast with an ignitor, it will run mh but because it's giving a kick of over 2500v to strike the arc (which it doesn't need) the bulb life would be reduced, although I don't know exactly to what degree or how quickly it would degrade, since I have never seen a test done on the long term effects of mismatching ballasts.

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Originally Posted by ceestyle
Don't be a martyr wasting $100 or more on CFLs to prove they're inferior for flowering pot.

Yes its a magnetic Ballast... Tahnks so much for the info... didnt get to switch the ignitor lastnight... will try do it tonight and report back.

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5,4,3,2,1 blunts pass off! Pick a planet, roll it, toke it, smoke it and we blast off...

sounds like the ignitor is shot since the MH works but not the HPS. MH does not need an ignitor therefore it is working. You can get an ignitor at any electrical supply store and they are alot cheaper than buying a whole new ballast. Good Luck

im interested to know how this turns out because im going through the same thing with my 1000w

an open ground will not cause a lamp to misfire. try bending the contact tab to make sure its making contact with the lamp base.

a ballast is basicly a transformer...transformers are generaly an ungrounded system because your taking your ground from the center tap of your transformer wich in turn is bonded to the system neutral at the utility connection on the primary side of you x-former...or in your case your picking up your ground through the wall socket your plugged into on the primary side ....your load side (to lamp) is getting its ground through the "common" connection on the ballast

EFF THIS!!! Ok so I changed the ignitor and its still not working!!! I really dont know!! ... Ok Im gonna open the ballast up and take a pic and post it on here to see if these people wired it right. I bought it from a local light store and it wasnt a pre-fab ballast. The store assembled it for me... (all they had were all in one units... light+ballast in one... got them to make a remote ballast.) Seeing as they said the total opposite to what you all are saying about the ignitor... its prob best to get your opinion on it.

Cheers... brb

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5,4,3,2,1 blunts pass off! Pick a planet, roll it, toke it, smoke it and we blast off...