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Discussion Starter · #1 ·
With the PJ up and running again and on the floor I'd like to take the opportunity to do some mods to it (an ECP 4100). :D :D :D


I've cut out the grills and now I'll buy new fans. I've read a number of threads in the forum but I still lack info. The Air flow and static pressure is very important to keep the temperature down especially when ceiling mounted. The specs for the two fans in my PJ seems to be:


DC 12V, 1,1W, .09A

Air flow 27 CFM (46 m3/h)

Static Pressure 0.06 (inch of water)


Is this correct?


I have two fans, should I consider putting in two more to improve the cooling (I've read that newer ECP-4100 have 4 fans)?


Can I use a fan with higher CFM and static pressure values to improve cooling or can that damage the PJ in some way?


Thanks for the help!

Henrik
 

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I'd like people to address this issue since I was planning on doing something similar to Nardjinku. Apparently you can buy ultra quiet liquid bearing fans (like the ones found in recent CPU power supplies). Since I'm planing my projector (ecp4100) between floor joyces I need to know the volume of air that need to pass through the system for proper cooling.
 

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Discussion Starter · #3 ·
Has anyone tried to put in 92mm or even 120mm fans instead?

Can a more powerful fan harm the PJ in any way?
 

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I have no experience mod'ing a ECP pj's, but have mod'ed the cooling systems on XG, Ampro 3600's, and helped a Marquee...in all cases, the more air movement the cooler the pj ran.

You cannot run one to cool, so adding fans shouldn't be a problem...unless you somehow create a null area where fans are pulling from different directions, and that end's up creating an area where no air is moving (very unlikely I'd imagine)

The best think you guys can do is visit a store like Wal-Mart, and buy several (I have four) digital thermometers, they're about $10 each, and you can find them in the hardware section. Install them on the hottest areas of your pj.
 

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While the heat transfer from a heat sink increases as the velocity of air increases, there is a point at which air turbulance can occur which creates a "layer" of air next to the heat sink that actually has very low velocity which can reduce the heat transfer. Since my experience with this goes way back in time, my only recollection is that it only begins to occur at very high velocities - Probably well in excess of what you would have with these cooling fans.

I agree with KennyG that more is better. The cooler these devices run, the longer they last and the less drift in their parameters. This also goes for other electronic equipment.

Thanks,

Bob
 

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Bob, I think what you are refering to is the point at which cooling air/ fluid moves so fast as to not have enough contact time to actually transfer the heat into the cooling medium.?
 

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Correct - The phenomenon is also for fluids. I had an experience many years ago with a liquid heat exchanger that was not working properly. When we reduced the flow rate, it worked fine. I did some subsequent research and found that little eddy currents are set up very close to heat exchanger surface which actually act as an insulator in high velocity situations.

Anyway, with projectors, I have found that the majority of unwanted sound actually doesn't come from air movement - It comes from the tight mechanical connection between the fan and the heat exchanger which amplifies the audible vibrations. Tap on a heat sink, and you will see what I mean - It will ring like a bell! If you isolate this connection in such a way as to not restrict air flow, you can have the best of both worlds - good air flow and reduced noise.

Thanks,

Bob
 

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Discussion Starter · #8 ·
Thanks guys!


I think I'll try to find some quiet 92 or 120mm fans and see if I can fit them in there. The reason for this question came from reading other threads specifying that you should try to find new fans with specs as similar a possible to the original fans specs. From the info above I draw the conclusions that the CFM and static air pressure shouldn't be less than the original fans specs but it's ok if they are higher.


Thanks again!


Henrik
 

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Yes, in all cases, higher air flow has led to lower operating temps.

If you are trying to get a quiter pj, in many cases you can mount a large fan in a different room, and run a duct to your pj. If your pj is built with most of it's heat producing compenents in one centeral area of the chassis...or the pj has a cooling system that flows in one direction, then steps can be taken that will eliminate most of the fans, and make it run cooler than the factory cooling system.
 

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I think it would be very hard to get too much airflow. Where I work, a/c ducts are placed directly under the tape machines to keep them at optimal operating temperatures. The sound of fans in the tape room is deafening...oh yeah and it's really cold in there too!


The best possible situation might be to somehow run an air conditioning duct into or very near the heatsink...I'll bet that would take care of any cooling worries.


Maybe the high-end folks have something like this done? Or an enterprising under 5K guy maybe?
 
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