My friend gave me a grow light ballast to try and fix, it's a yield Lab 1000watt HPS/MH ballast with a brightness selector and alot of electrical stuff inside I don't quite understand...

The issue at the moment is it does not output any voltage whatsoever, however the cooling fan still spins. What do I need to replace or do to make this ballast work again?

I have a few Yeild Lab,Growers Choice ballasts.when a digital ballast is first energized-the digital circuits in the ballast do a self check to see if they work properly.If there is faults in the circuits or actual ballast circuits the ballast shuts down.Does the ballast have any sort of indicator lights on it that light to tell you what its doing?Is there a bulb connected to the ballast-many of these digital ballasts won't activate unless a bulb is connected.Look on the Yeild Lab website for info on your ballast.They may be able to tell you whats going on with the ballast.

My friend gave me a grow light ballast to try and fix, it's a yield Lab 1000watt HPS/MH ballast with a brightness selector and alot of electrical stuff inside I don't quite understand...

The issue at the moment is it does not output any voltage whatsoever, however the cooling fan still spins. What do I need to replace or do to make this ballast work again?

I think is best to use a magnetic, the magnetic don't have electronic components inside (capacitors, transistors), but need more components and have more weight. 

If yow want to repair the digital ballast, you need to find the overloaded component and replace it (normally in the circuits fails the capacitors and the integrated circuits)

I think is best to use a magnetic, the magnetic don't have electronic components inside (capacitors, transistors), but need more components and have more weight. 

If yow want to repair the digital ballast, you need to find the overloaded component and replace it (normally in the circuits fails the capacitors and the integrated circuits)

When I mean "to use magnetic ballast" I say you can use a limited transformer as ballast.