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View Full Version : Flat Cooling Units for DTIVO's - Any AC/DC ones out there?



SithLord
09-06-2003, 01:19 AM
I was researching those flat styled cooling fan contraptions, described as notebook coolers. However, all the ones I've seen are USB-powered. Does anyone know if there are any AC/DC electrical ones? I'd prefer to plug it into my UPS alongside my DTIVO.

Or is there a way to get an adapter for a USB connection that will change it to an AC/DC connection?

Just wondering. Thanks.

FredThompson
09-06-2003, 01:47 AM
Seems easy enough, it you really want this, to use a transformat on your AC source and apply it to just the pins you want to carry the power.

If there any reason you can't use a torx bit and take the cover off?

Some people attach fans to the 4-pin power connectors for the hard drives.

SithLord
09-06-2003, 01:57 AM
Thanks. Someone has PM'd me with info on a unit sold by Cyber Cooler. It has an AC adaptor capability. If anyone is interested, it's model # NK-360 and goes for $21.95.

FredThompson
09-06-2003, 03:27 AM
Is there a reason you cannot open the unit? There's quite a variety of 4-pin fans, some are very quiet. I have the cover off my T60 and it never overheats. There's about a foot of clearance above it and the heat just naturally conveys off. Don't be surprised if the ambient noise level starts to shoot up with the type of fan you're describing. You'll be trying to force air through a number of small vents, right?

One of the biggest noise creators, other than old-style drive bearings, is air cavitation. If fans aren't designed efficiently, they create a vacuum behind the fins. As those fins move, air is continually collapsing to fill that vacuum behind the fins. This makes a lot of noise. It can also happen when air is forced over an abrupt right angle like slots punched in metal. This is one reason some people use round wire grilles on their comptuer fans and most decent room fans have round wire grilles. Air will flow around them without cavitation.

Oh, uh, and cheap bearings in the fans.

In my PCs, I've swapped out the standard heatsinks for Thermalright SLK-800s and use 80mm Vantec Stealth fans. They are very, very quiet. Part of that is highly efficient design, part is using a large fan, temperature controlled, to move air. A small fan will cavitate more than a large one. It is so quiet in my office, which has 4 PCswithin 6 feet of my chair, that I frequently forget if a computer is on. The noise of air being moved through the house when the heat pump is on is louder than those fans.

Oh, yeah, I also got rid of the older power supplies and use Okia brand because they're very quiet and easily available at the local PC shop I frequent. There's a lot of good info at http://www.7volts.com about reducing noise and increasing cooling.

If you're willing to remove the cover to put something inside and want to re-install the cover, do yourself a favor and look through that site.

SithLord
09-06-2003, 03:51 AM
Because of the configuration of my T60 and other components, removing its cover is not an option. The cooling unit I looked at got very good reviews for its performance. One positive about is that it's extremely quiet, which is fine with me. :)

FredThompson
09-06-2003, 04:59 AM
Removing the cover is not an option or running without a cover is not an option? If your T60 is in the middle of a stack of components...

Think about the configuration of the T60 and what you really want to accomplish.

The chips that get hot are on top of the large motherboard, underneath the drives, shielded by the drive bracket, in the middle of the board. The board almost completely fills the case. If you have 2 drives in your T60, the chips are covered. Under the motherboard should be a rubbery sheet with some adhesive that holds it to the case bottom.

How is this fan unit, mounted underneath and externally, going to direct air flow to those chips through the solid metal base of the T60's case? Even if it manages to pull a little heat away, it's not going to do much for the chips because of where they are and what would cause the case bottom to get hot. I suspect the biggest heat problem actually comes from the hard drives. Drives get hot and there's little ambient air flow inside a closed T60 Granted, there's a fan near drive 1 but it's not that powerful.

There's a thread or two around here that discussed cooling modifications. What you're thinking about will move air. Will it move air where you want it to?

Another idea might be to use those heat pipes that are showing up for hard drive cooling. I don't know if there's enough room above the drives, though, or where you would move the heat.

Truett says they replace a lot of tuners because the aluminum shield doesn't touch the top of the IC so there's no heat transfer. I've toyed with the idea of bending those shields in and using a little phase-change tape to secure them to the tuner.

Another thought, and something I've been considering lately just in case my cats get too curious, is to bend a properly-sized piece of metal grating to act as a cover.

Silverdude
09-06-2003, 01:34 PM
I was going to post this when i got some pics, anyways...

Looking down on the Dtivo, with the front towards you it goes harddrives, fan, firewall, a narrow trough with 3 transistors, a narrow slot for the hot air to excape and the outside wall of the DTivo cover. with me?? After crossing the transistors, think about how narrow that space is, and think about the air trying to get out of the case, it also doesnt help that the air is being forced down out the bottom. (Hot air wants to rise....)

I cut a whole the same size as the trough that holds the 3 transistors on the outside of the Dtivo case. I am not at home right now, but its about 1.25"x 1.25" square.

The normal running temp was 53 - 54 degs on worm days (house around 28), 49-51 when the A/C was on keeping the house at 23.

Now, the temp is 48-49 on the warm days, 47-48 on A/C days.

I also plugged up all the holes around the fan to make sure the air goes across the transistors, not around in little circles inside the case.

SD

As a side note, i would like to replace the fan with a higher capacity fan (same size) , if someone has done this send me a link to the fan you bought.

FredThompson
09-06-2003, 05:15 PM
With no cover, my T60 reports an internal temp of 41. That's why I'm so interested in running without the top ;)

You might want to poke around tenmax.com for thin fans.

GREEK
09-06-2003, 06:34 PM
All the notebook coolers around are known to die young. They are not meant to run 24/7 and the fans burn out. get small rubber feet to loft your tivo 1/4 to 1/2 an inch up and split the bottom in half front to back with air condition foam, the kind with a sticky tape on one side, usually comes in the box when you buy a window ac. This prevents the hot air coming out the powersupply side from getting in the cool air side to the left. WIll drop your temp 5+degrees celcius.
EDIT: the air ocnditioning foam is soft, not like the foam block stuff. It is like the size of a pack of cigarettes, with sticky tape on the thin side. It will squeeze to seal the middle of the tivo, and is perfgect if you get little sticky feet. THey have the perfect ones at radio shack for 2 bucks for like 20 of them, theyre black and tapered, and home depot/lowes/any hardware has the AC sealing foam. You can use anything that will split the tivo in two and prevent the hot air from getting sucked back in. You can also note on the powersupply there is a small piece of plastic divider so the air doesnt come back over. The only really hot part is the huge aluminum fin in the way of the fan and the caps. ANY air moving is cooling better than stagnant air. Mainboard chipset soolers from COMPUSA work awesome, 10 bucks each set of two(the short ones...need room for the HD rack) grab 2 packs and stick em on the 4 main chipsets, cools like a dream......

Silverdude
09-06-2003, 06:58 PM
Originally posted by FredThompson
With no cover, my T60 reports an internal temp of 41. That's why I'm so interested in running without the top ;)

You might want to poke around tenmax.com for thin fans.

Just because the temp shows lower does not mean that the temp is lower. It just may mean that the temp sensor is not getting the hot air blowing over it any more. Also after removing the top, there may be areas that need cooling are not getting flow any more either...

SD

FredThompson
09-06-2003, 08:15 PM
Thinking about it now, I guess it is possible the internal fan is supposed to cool more than the chip next to the power supply but there's very little room for air to move.

I've got another idea which might work out quite well. There's a noiseproofing enclosure for drives up to 5400 rpm. Might be a great way to move drive 2 outside the box. Won't look that greate but it will be silent and reduce heat.

yeah, sensor-reported heat, that's true.

Good idea to isolate the power supply area. Think I'll grab some of that weatherstrip stuff tomorrow.

Pro-289
09-10-2003, 11:00 PM
I got my tivo opened up on a table too. Got a case fan blowing on the power supply heatsink and caps, and little 486 CPU fan with a little cereal box cardboard on one side to make a 90deg angle over the tuners, that way it blows diagonally over the tuners to cool'm. I also modded the fan molex connectors to use 5v instead of 12v, that way it's even quieter.

If you're going to put a fan on the case to blow or suck air, ya gotta think about dust too. The more air ya move, the more dust ya move too. Think about a filter inline with your intake. And you only need a little bit of air flow which beats no air flow. So don't think you need 36 CFM ripping through the case. Heck, get a 120mm fan and use 5 volts instead.

FredThompson
09-11-2003, 12:20 AM
No doubt about it, a larger fan doesn't have to work as hard to move air, think how a ceiling fan works. It moves a significant amount of air continuously but without a lot of pressure.

It's similar to the practice of downclocking to reduce heat and increase reliability on low-demand CPUs.