So I've been building my projector for the last couple weekends. I have everything put together. I am using the 400W Ushio bulb with UV/IR filters, split design, 17" LCD.
My problem is cooling. I have 2 squirrel cage fans. One is placed right above the bulb and is sucking air out. The other is mounted so it blows cooler air across the back fresnel. After an hour or so, the temp between the back fresnel and the filters is around 105F. The temp in between the LCD and the field fresnel is 105F-ish. Are these temps that other people are getting? I read GG was getting 88F-ish temps with just one 65CFM fan. I have two (supposedly) 100CFM fans.
I have about 12 holes lined up vertically (see pic) for air intake. I think I just have bad venting. I need some advice for placement of fans and vents. When I take the cover off, the temps drop about 10 degrees or so. My first thought on this is to put convection vents on the top (light leakage nightmare). I don't want to put 100 holes in this box trying different air flows. Also, my back fresnel is bowing from the heat. Help?
My problem is cooling. I have 2 squirrel cage fans. One is placed right above the bulb and is sucking air out. The other is mounted so it blows cooler air across the back fresnel. After an hour or so, the temp between the back fresnel and the filters is around 105F. The temp in between the LCD and the field fresnel is 105F-ish. Are these temps that other people are getting? I read GG was getting 88F-ish temps with just one 65CFM fan. I have two (supposedly) 100CFM fans.
An externally hosted image should be here but it was not working when we last tested it.
I have about 12 holes lined up vertically (see pic) for air intake. I think I just have bad venting. I need some advice for placement of fans and vents. When I take the cover off, the temps drop about 10 degrees or so. My first thought on this is to put convection vents on the top (light leakage nightmare). I don't want to put 100 holes in this box trying different air flows. Also, my back fresnel is bowing from the heat. Help?
cooling
105 F is probably not so bad. But that 10 degree drop when you get more air into the box really says it all: You are restricting input air, which restricts the output. Make some more holes and cover them with a black cloth light filter.
My temperature report was for a 250 Watt lamp, not a 400. (I just got a 400 today, so I may have some updated numbers by the weekend.)
One big difference between our designs: My lamp is mostly surrounded by aluminum to form a heat shielding "light box". All of my 65 CFM is pulled through that light box, and the box cross section is only about 3" by 4". So the whole length of my Ushio retrofit lamp has pretty high air flow over the surface. So does the inside of the aluminum light box. That means that a lot of heat is pulled right out of the box, without mixing with the rest of the air inside. Then I have a good Rosco hot mirror covering the light hole in the top of the box, so no IR gets out and no air leaks into the light box that way.
I planned to make the air flow across each layer (fresnels & LCD) to the other side of the projector, before it went to the next layer. But I found I didn't need to worry about that. I think the key is not letting the hot air around the lamp carry heat to the rest of the projector.
If your fresnel is sagging, support it with a piece of Lexan XL10. Works great & it is a very good UV filter too.
105 F is probably not so bad. But that 10 degree drop when you get more air into the box really says it all: You are restricting input air, which restricts the output. Make some more holes and cover them with a black cloth light filter.
My temperature report was for a 250 Watt lamp, not a 400. (I just got a 400 today, so I may have some updated numbers by the weekend.)
One big difference between our designs: My lamp is mostly surrounded by aluminum to form a heat shielding "light box". All of my 65 CFM is pulled through that light box, and the box cross section is only about 3" by 4". So the whole length of my Ushio retrofit lamp has pretty high air flow over the surface. So does the inside of the aluminum light box. That means that a lot of heat is pulled right out of the box, without mixing with the rest of the air inside. Then I have a good Rosco hot mirror covering the light hole in the top of the box, so no IR gets out and no air leaks into the light box that way.
I planned to make the air flow across each layer (fresnels & LCD) to the other side of the projector, before it went to the next layer. But I found I didn't need to worry about that. I think the key is not letting the hot air around the lamp carry heat to the rest of the projector.
If your fresnel is sagging, support it with a piece of Lexan XL10. Works great & it is a very good UV filter too.
That's a nice design for the light box. I wish I had thought of something like that before building. Oh well. I do have flashing that covers the bottom, back, and top of the bulb. My wood was getting REALLY hot (couldn't touch it from the outside) so I thought it was a good idea. Couldn't hurt as extra reflection too. Anyways, I have my sawed off ladle reflector in front of the flashing behind the bulb.
I think you are absolutely right in that I don't have enough air intakes. I think I am going to get a couple 80mm fans and have them blowing air in directly between the filters and back fresnel (so there is air coming from both directions). What about some simple convection vents above the LCD / Fresnels?
I think you are absolutely right in that I don't have enough air intakes. I think I am going to get a couple 80mm fans and have them blowing air in directly between the filters and back fresnel (so there is air coming from both directions). What about some simple convection vents above the LCD / Fresnels?
convection vents
I suppose you could try that, if there is no other air flow there.
My original design concept was to make all of the air flow from the coolest area to the hottest area. That way, it can always remove heat as it passes through. To implement that, you have to divide the projector into multiple compartments:
The air enters at one side of the compartment containing the back of the projection lens, (maybe) a front-surface mirror, and the top of the field fresnel. It leaves this compartment through a slot on the other side of the box. (This way it sweeps across the surface of the fresnel.)
It then sweeps across the compartment formed by the bottom of the field fresnel and the top of the LCD. It exits through a slot on the other side of the compartment.
It then sweeps across the compartment formed by the bottom of the LCD and the top of the condensor fresnel, and exits through a slot on the other side of the compartment.
(If those two compartments are so small they constrict the air flow, then you divide the flow between them by making them parallel instead of serial.)
It enters the compartment containing the light box and has to flow across the the other side, where the lamp socket is mounted at the open end of the light box.
Then the air flows through the light box around the lamp, through a duct, and to the fan that pushes it outside the projector.
I think this kind of design gives you maximum cooling because the air flowing over a projector area is always cooler than those parts, even if it did pick up some heat in a previous compartment. For example, even if the air is 120 degrees F by the time it reaches the light box, that will still cool the lamp.
I suppose you could try that, if there is no other air flow there.
My original design concept was to make all of the air flow from the coolest area to the hottest area. That way, it can always remove heat as it passes through. To implement that, you have to divide the projector into multiple compartments:
The air enters at one side of the compartment containing the back of the projection lens, (maybe) a front-surface mirror, and the top of the field fresnel. It leaves this compartment through a slot on the other side of the box. (This way it sweeps across the surface of the fresnel.)
It then sweeps across the compartment formed by the bottom of the field fresnel and the top of the LCD. It exits through a slot on the other side of the compartment.
It then sweeps across the compartment formed by the bottom of the LCD and the top of the condensor fresnel, and exits through a slot on the other side of the compartment.
(If those two compartments are so small they constrict the air flow, then you divide the flow between them by making them parallel instead of serial.)
It enters the compartment containing the light box and has to flow across the the other side, where the lamp socket is mounted at the open end of the light box.
Then the air flows through the light box around the lamp, through a duct, and to the fan that pushes it outside the projector.
I think this kind of design gives you maximum cooling because the air flowing over a projector area is always cooler than those parts, even if it did pick up some heat in a previous compartment. For example, even if the air is 120 degrees F by the time it reaches the light box, that will still cool the lamp.
My idea is going to do double duty (I hope). I am going to place two fans (80mm 25CFM; 90mm 40CFM) on the same board as the squirrel cage that blows across the back fresnel. They will both blow in that general area but they will have air ducts from the front of the box via PVC piping and a few air vents.
This should bring in cool air to the box and help cool the fresnels. The squirrel fan above the bulb should be power enough to remove hot air sufficiently.
Thanks for the advice!
This should bring in cool air to the box and help cool the fresnels. The squirrel fan above the bulb should be power enough to remove hot air sufficiently.
Thanks for the advice!
You already have enough fans with 2-100 cfm-ers. The problem is air restriction. I suggest the first thing you do is open up those 12 holes into a slot. This will double your airflow. Then partially block off under neath the IR filter. This will cause the air to flow down past the LCD and then upwards across the fresnel. Then see what the results are and take it from there.
I think my cooling solution is just poorly set up. I am getting around 130F (I was mistaken before) around the fresnels and LCD. That's above the operating temp of most LCDs. Gonna redesign this. That's just too hot. I'm thinking of putting two slots in the back (beside and behind the bulb) and two in the front. Any advice as to the intake air placement? Behind the mirror or beside the projection lens?
Not a bad idea. I might experiemtn with that. In the mean time, I have installed the 2 fans (80mm, 90mm) in the same place as the "fresnel" squirrel fan. The fans are placed above and below the squirrel fan.
I have to say that the squirrel fans are not very good for blow air across components. They are ok for sucking air out. The 90mm fan is 40CFM and the 80mm is 25CFM. They are both MUCH quieter than the squirrel fan and they cooled the fresnel temp from 130ish to 110ish (F). 20 degree drop. Awesome! I am going to run PVC to the outside of the box from the fans. That should ensure the system stays cool.
I have to say that the squirrel fans are not very good for blow air across components. They are ok for sucking air out. The 90mm fan is 40CFM and the 80mm is 25CFM. They are both MUCH quieter than the squirrel fan and they cooled the fresnel temp from 130ish to 110ish (F). 20 degree drop. Awesome! I am going to run PVC to the outside of the box from the fans. That should ensure the system stays cool.
I have another question about cooling. I read someplace that if the LCD gets too hot it will turn black. Does the LCD fade to black gradually or is there a certain limit the LCD can take and then it just blacks out quickly?
I ask this because it seems like I have a great bright image and later on, it seems to darken. I could also be my eyes. It seems like my collimator (back) fresnel is bowing just a little from the heat. I'll have to check my temps when I get home, but I think they are all under 120F (around the fresnels and LCD).
Here is my setup. I have a vertical slot about 11" tall and 1.5" wide. I have another rectangular opening about 5" tall x 3" wide. The rectangular hole has a light blocking panel at an angle (the black line). So it looks like a half open door. I have one 100CFM fan for exhaust and three fans (90mm 25CFM square, 80mm 23CFM square, 100CFM squirrel fan) blowing across the back fresnel (the space between the back fresnel and the IR/UV filters).
If my cooling isn't good enough, I was thinking:
1. I would move the squirrel fan so it blows between the LCD and the field fresnel
2. Make all three fans blow across both the LCD and field fresnel
3. Move the squirrel cage fan so it's used as an exhaust (so both squirrel fans are exhaust) and use the two square fans to blow across the LCD and back fresnel.
Any ideas?
I ask this because it seems like I have a great bright image and later on, it seems to darken. I could also be my eyes. It seems like my collimator (back) fresnel is bowing just a little from the heat. I'll have to check my temps when I get home, but I think they are all under 120F (around the fresnels and LCD).
An externally hosted image should be here but it was not working when we last tested it.
Here is my setup. I have a vertical slot about 11" tall and 1.5" wide. I have another rectangular opening about 5" tall x 3" wide. The rectangular hole has a light blocking panel at an angle (the black line). So it looks like a half open door. I have one 100CFM fan for exhaust and three fans (90mm 25CFM square, 80mm 23CFM square, 100CFM squirrel fan) blowing across the back fresnel (the space between the back fresnel and the IR/UV filters).
If my cooling isn't good enough, I was thinking:
1. I would move the squirrel fan so it blows between the LCD and the field fresnel
2. Make all three fans blow across both the LCD and field fresnel
3. Move the squirrel cage fan so it's used as an exhaust (so both squirrel fans are exhaust) and use the two square fans to blow across the LCD and back fresnel.
Any ideas?
maybe
Maybe all of that fan flow inside the lamp compartment is mixing very hot air from right around the lamp with the cool incoming air, and then recirculating it past the fresnel. Try making your UV filter mount go all the way to the side of the enclosure, so hot air can only exit at the left. Ideally, it should also reach all the way to the front and back surfaces so the air gets into the lamp compartment only through a large slot at the top of the drawing.
You could also build more of a duct system around your lamp, so the exit fan would pull air past the lamp at higher velocity. Then that hot air would be less likely to mix with the cool incoming air.
Maybe all of that fan flow inside the lamp compartment is mixing very hot air from right around the lamp with the cool incoming air, and then recirculating it past the fresnel. Try making your UV filter mount go all the way to the side of the enclosure, so hot air can only exit at the left. Ideally, it should also reach all the way to the front and back surfaces so the air gets into the lamp compartment only through a large slot at the top of the drawing.
You could also build more of a duct system around your lamp, so the exit fan would pull air past the lamp at higher velocity. Then that hot air would be less likely to mix with the cool incoming air.
yeah, i would try and restrict the hot air flow to the rest of the box and try and pull most of it out from the lightbox, good luck
- Status
- Not open for further replies.