In my original desing and pj construction I placed my Ballast in an air tight enclosure seperate from the rest of the pj. I am now concerned that this may present a heat issue.

My question is do the ballast's produce heat themselves, and if so is it enough to require ventilation? I would rather not tear my system apart to provide venting for the ballast but also am not excited about things melting and burning down.

Please help!

Eballasts have fans on the back normally and CANNOT be placed in an airtight environment.

Magnetic ballasts produce large amounts of heat and I would recommend having a good airflow past these.

Definite fire risk!

Not what I was hoping to hear, but good to know none the less.

Here is a picture of my eballast enclosure from when things were coming together, If I provide adequate ventilation is there any issues with wires touching the eballast? I have had this running for up to about 20 min without ventilation on the eballast and no problems. Glad I asked before running an entire movie!!!!



Here is th after shot, The eballast space was enclosed with a lid...

Unless you sealed those holes where the wires enter, it's not "airtight".
If you cut a slot or two in that board that the wires go through, you should be fine. Or maybe cut louvre ventilation slots in the metal flashing below your lamp.



The unpainted metal flashing might be throwing stray light towards your rear fresnel. You also might want to consider painting it with some flat black BBQ Grill paint.

Thanks for the input everyone, slots it is, and that shouldn't be too obtrusive.

To be honest, I'd have the eballast outside of the enclosure as far away from the bulb as possible.

They are called "Remote Ballasts" for exactly that reason - they can be used from a remote location relative to the bulb.

You're only going to reduce the lifespan of the equipment having it near a heat source.

But... it's separated by a sheet of flashing.

Flashing only reduces the radiated heat, not the convected heat (or conducted heat if the ballast touches the flashing).

You're better off having the ballast outside so it's own fan can cool it more effectively.

Try this one (Also see image)...

I put the vents at the front of the eballast enclosure to prevent any backflow of heat from the lamp. Then add small intake holes at the rear of the enclosure. I readjust my flashing so that it is lifted off of the wood and there is an airspace between.

The eballast would have about 1/4 to 1/2 inch clearance on top, 1/2" of wood, 1/4" of air space, flashing, and then the bulb. I hope this would provide adequate reduction in heat transfer from the lamp, it was my whole reasoning for the separate enclosure... . I would really like to hear what the pros think though...

Also with this configuration a few questions arise...

1.If I have wires directly against my eballast in the enclosed space, would I need to worry about melting issues?

2.Also, I know its been posted but can't seem to find the critical temperatures. The space between my safety glass and LCD currently measures in the upper 70's and Im curious what my limits are as I make mods. I plan on monitoring the enclosed space for the eballast after I make the breathing holes and seeing what numbers I come up with.

3.I noticed Quasi mentioned painting the flashing bbq black, can you elaborate as to what this helps, don't I want stray light thrown towards my fresnel?

I greatly appreciate all the feedback, THANKS!

It looks like a good setup. Is the air intake slot between your LCD and rear fresnel (as it should be), or between your rear fresnel and heat glass?

I don't think the wires touching the eBallast enclosure will be a problem. If others think it's a problem, please correct me.


http://lumenlab.com/wiki/index.php/DIY_Pro...Keeping_it_Cool

You only want the light coming from the lamp's arc (center) hitting the rear fresnel. That's the closest thing we can get to a "point" light source (think laser beam). Therefor, any light hitting the rear fresnel that is not coming from you arc is detrimental.
http://lumenlab.com/wiki/index.php/Light_Flow

Thanks for the input quasi!

I ran the projector for about an hour tonight and took temps. I drilled some preliminary holes in the eballast enclosure for this purpose but did not create a ventilating system, just wanted to find out what it's currently running at. The enclosure went up about 20 degrees in the first 30 min to 85.8 F (Keeping in mind this is without any ventilation). When I turned the PJ off an hour later the eballast enclosure was holding steady at 104 F. The main lamp chamber seemed to rise and hold steady at 101.3 and the space between the rear fresnel and LCD stayed in the mid 80s.


Yup, got the air intake in the right spot, I'm know curious to see what the temp will do in the eballast area after I create the venting system.

Painting all of my flashing bbq black in the next couple days, hopefully will have pictures up next week after I finish the screen.

Thanks again.

Fired her up for her first full movie last night in the back yard. Even had a live studio audience for the showing. Put together an 8' by 13' screen and this baby looked sweet, what did I do with myself before my PJ?

Anyway, I wanted to continue some discussion on heat, I am curious now that I have run a full film and have ideas on my run temps as to what temps are critical in areas away from the LCD. My main compartment seems to be fine and the area by the LCD didn't even cross 85. Although, the lower compartment box I mentioned in this thread is still concerning me. I added the new ventilation and the lifted flahing as shown in the previous diagram but at the end of the film my temp was still going up. At about 2 hours of run time the compartment was at 119 F. So at what temp do wires melt? And is 119 degrees a temp that will have major negative affects on my ballast?

It seems like from my earlier research days I saw pictures of guys putting their eballasts fairly close to the bulb. I would imagine that would come close to the 100s also...

Thanks again guys.

I would say that the LCD temp is the only real concern. Keeping the rest of the rear compartment cool is simply a side effect of cooling the LCD.
If you have safety concerns about the compartment that holds your ballast, you can line it with flashing (no need to paint it as it will be hidden). If you have concerns about the wiring, you can shroud it with high-temp split loom. I don't think there is any threat of melting unless it's actually exposed to open flame.

Well, water boils at 212F. Wires aren't going to melt in boiling water, nor will the insulation.

The biggest threat to the wiring in your projector is the exposure to the UV that the lamp creates. This will eventually make the insulation on the wiring brittle (Unless the wires are covered with a nylon wrapping.) This could cause a short circuit if you move the wires around and the insulation flakes off, but that's what the circuit breaker is for. I also protect my wiring from direct exposure.

As long as you keep some airflow there, it's all good.

The LCD panel is another matter. It should be kept blow it's rated max temperature, which is typically around 90F. As long as you are drawing in cool air over the LCD, you should be fine there.