retrofitting OHP with MH

probably not worth it

It would be difficult on several levels... you'd have to replace the elctronics - the ballast I believe you'd call it. You'd also have to replace the fans, perhaps even "cut-n-gut" to install additional fans for the greater cooling you would need for the hotter bulb. It would probably be best just to spend a little more for an OHP that already uses MH.

It's also possible that the optics would then be wrong after all your efforts... the reflector and the lens might not have suitable properties and measurements for your new bulb which not only be brighter but in a different place, a different size, etc... I envision "hot spot" difficulties in your picture.

Of course I am only taking guesses here as to what kind of problems you're likely to run into, as I've never tried it myself.
 
I think i remember someone on the big threads doing it and getting good results... but crunching thought those things is a pain.
Anyhow, the bulbs they seem to use in the commercial MH OHPs are expensive and have low life times... the electronics/modding isnt too big a problem..... and the optics should be okay because the focal lengths of the fresnels should pretty much be set properly.. i think the only thing i may need is a new reflector and condenser.

.............I guess there is only one way to find out ;)
 
It depends on the panel and the overhead. My sharp qa-1500 panel has built in fans in it which keep it fairly cool. I can run it on a 600watt halogen projector and have no heating issues. A lot of metal halide projectors were designed to work with lcd panels as this was the reason many people were buying them.
 
575W MH vs. 600W Halogen

575W MH vs. 600W Halogen

How do these two lamps (and their respective OHPs) compare? Usage economy seems about the same... one is expensive but lasts forever, one is cheap but burns out fast,

I'm wondering about the image quality and total light output. There are only one or two 575W MH OHPs on Ebay at any given time as compared to about a dozen old clunky, dirty looking models that take that 600W halogen bulb, and they sell for about $100 cheaper. (about $140-$170 for the MH OHP and between $40-70 for the Halogen ones.)
 

DPW666

Member
2002-04-28 10:24 pm
I just bought a 3M 522 that uses BVE lamps. 625 watt and 75 hours. I can't find those bulbs anywhere here. I too am considiring retrofiting with MH. Lasts mucho longer and I am sure it will be mucho brighter also. With my Ovation 820 panel I get an acceptable image in total dark and it gets so hot that the panel suffers discoloration after some time. And god 625 watts thats gonna raise the bill like hell! So if anyone has tried to do it with a 400 watt MH please let us know!
 

eebasist

Member
2002-04-10 5:06 am
If you are serious about projection, get the MH one by all means......a 575W MH will kill a 600W halogen. Halogen lights wast much more engery in the form of heat rather than MH. Its worth the extra cash if you're looking for a bright light. MH also gives better light in general as well, you can get 5K kelvins out of them depending on wich one used.