Help me find FAN for entertainment unit heat

Hi guys! Happy new year's eve!!

We bought a cable unit for our new LED TV and put the unit in our enclosed entertainment furniture cabinet. It all looks great and works well however if we close the glass front door on the entertainment furniture the cable unit is not getting any airflow to help cool the unit and it's internal fan comes on to try to help.

I was thinking of opening a 2" or 3" hole in the back and sitting or mounting a quiet fan to help circulate the air. For convenience, I need a fan that can plug into the AC outlet in the back of the cable unit.

Do you guys think that this fan would do the trick to be able to shut the door while using the TV?
Can anyone point me to a fan that will do the trick?

Thanks for reading

That should do the trick. You just need enough air-flow to provide a fresh load of air to heat. Make sure there is an intake of some sort (even cracks around the door) to let the fresh air in.

You can find a variety of small fans at MPJA.com. You'd want an AC model such as the ones on this page;
http://www.mpja.com/listitems.asp?dept=47&main=46&type=1

I think i did some noise measurements in my house and found that the TV sound was normally 60 - 64 db. A fan down in the below 50db should be good. I've had good luck with mpja.

BTW, that's a seriously cool TV.

Daniel

I would look into using the sort of fan that cools a computer. They are quiet and effective. They are designed to run from the PC power supply which is DC and I think 6V or maybe it is 12V (not sure). So you would need a small transformer to power it. But that will keep a flow of air through the cabinet and keep the heat down.

Or if the internal fan on the cable unit can be ducted somehow, you could duct that airflow to the exterior of the cabinet.

You can also use a 120mm DC fan by using one of those spare 6 to 9 volt wall worts. Panasonic Panaflo L (low speed) series, Nexus or Globe fans are very quiet from what I understand.

Cheapskate that I am, every time I have ever had to replace a computer power supply, I rip out the fans (and other useful parts) and toss them in a box.... Then when I need a little airflow somewhere, I use one running off a 'wall wart'.... which I also save when the devices they power quit working.

I think I have about six of these things set up for one task or another between the house and the workshop.

Packrat? Me ? No... well, YES!!.

What's the model of the TV set?

Thank you everyone for all the help. I think I be able to solve this pretty easy now. The Motorola DVR Cable unit that I'm renting from Comcast is the one that gets hot and also came with explicit instructions to keep it on its own in a ventilated space. We'll just need to give it a bit of help.

The TV is a new 37" Sharp Aquos HDTV. I did a lot of research with a lot of online comparisons and this brand/model consistantly got great reviews from end users and pros too. Here's a pic from the last get-together we had at my place.

Hey Crom,

For what it's worth, I think the sharp Aquos line are the best LCD tv's out there also.

One of the reasons why DVRs are large-ish and don't have a lot of fans is to control noise. There was a conscious decision made by the manufacturers that they'd make an oversized unit to allow for convection cooling rather than making a smaller unit with a fan, because the unit would likely be running 24/7.

A lot of equipment runs just fine at elevated temperatures.

You may very well be just fine with only the air holes cut in the cabinet. Then it can make its own way out. Cut a hole up top and one down below. I bet it will all be just fine.

These things are like leds. They are just happy at temperatures we think are too hot.

OK, I'm not an expert but....

NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO

Yes, many manufacturers use large cases to keep from having to have fans direct the airflow. No, many DVR's Do have fans; My Tivos (all three) and my DVD recorder both have fans. Heat buildup can be a problem with many electronic devices.

No, you can not always rely on convection. I did a sophisticated display at a trade show a few years back. It was driven by and Apple computer hidden in a podium. It did not occur to me that the heat would build up despite the gap below the door and the 2 inch hole at the top of the cabinet for cable pass-through. The show opened without my fancy display as the computers had both fried overnight.

Don't forget, solid state electronics have three enemies; excessive heat, excessive voltage and excessive vibration. All you need for a failure is for one component out of the 500 or so in the cable box to fry itself. Then you have to pull it out and drive to the cable store. Yuck.

These things are like leds. They are just happy at temperatures we think are too hot.

Click to expand...

There is happy, and there is happy. When the temperature changes so does the current draw. That's a "fundamental element of a semiconductor" according to my books. When you have enough changes, the circuit no longer works as designed. If you look at the docs, you will often find the correct temperature range.

Of course, sometimes you get lucky. My son abuses his equipment like you can't beleive. He's also constantly fixing / replacing things.

Ok, Sorry for the rant.

Daniel

gadget_lover said:

When you have enough changes, the circuit no longer works as designed. If you look at the docs, you will often find the correct temperature range.

Click to expand...

Yeah, thermal runaway is one of those little phenomenons with semiconductors. It's like a miniature version of the China syndrome. With it's negative temperature coefficient with respect to resistance, it conducts more heavily as it gets warmer, which makes it get warmer, which makes it conduct more...


That's one of the things that vacuum tubes have over semiconductors. They can withstand so much abuse that I've had tube plates glowing red hot (literally!) from overdriving them and they still worked fine afterwards.

To followup a little:

1. check the docs for temp ranges; oftentimes these temps are at the 100F mark or so.

2. don't be stupid about all this though

3. a fan will pull in more air, from close to floor level, which will draw in dust, which will get into the equipment, which will coat heatsink surfaces and overheat equipment, both of which will kill equipment

4. When doing a little r/d on a project about 5 years ago I had a computer enclosed in a non-ventilated steel box, 20 feet in the air on a pole, in the bald open sun, in the 90F+ mississippi summer. Interior temps were scorching. The pc ran just fine for months and months. My best guess at temps inside there were about 150F+. Also, the box had a window, so it also had a little greenhouse thing going on.

You may be able to get away with putting some went holes in the top of the back and some more in the bottom of the back. Since heat rises it will create a slight movement of air from the bottom to the top, you may be able to get away with just that.
If not pc case and power supply fans are designed to be fairly quiet already and you can run them air lower voltages to cut down on the speed/noise though you may need to add more than one then.

turbodog said:

To followup a little:

3. a fan will pull in more air, from close to floor level, which will draw in dust, which will get into the equipment, which will coat heatsink surfaces and overheat equipment, both of which will kill equipment

4. When doing a little r/d on a project about 5 years ago I had a computer enclosed in a non-ventilated steel box, 20 feet in the air on a pole, in the bald open sun, in the 90F+ mississippi summer. Interior temps were scorching. The pc ran just fine for months and months. My best guess at temps inside there were about 150F+. Also, the box had a window, so it also had a little greenhouse thing going on.

Click to expand...

Wow. That's impressive. What kind of PC did you have in there? Where did you find power supply that required no cooling?

Re: dust. The dust will cut the heat sink efficiency X percent. The extra air moving past the heat sink will increase the efficiency by Y percent. In most cases, Y is many times greater than X. The engineers among us can probably provide the figures; I can't.

Yeah, I'm anal. I figure if the manufacturer specifies an operting temp of 40 to 95, I should keep it within those limits if I want to maximize the life of the equipment and minimize problems. It has generally worked for me.

Daniel

Lurker said:

I would look into using the sort of fan that cools a computer. They are quiet and effective. They are designed to run from the PC power supply which is DC and I think 6V or maybe it is 12V (not sure). So you would need a small transformer to power it.

Click to expand...

There are small fans of this type that run directly on 120V AC power. Radio Shack used to sell these, and they still might.

big lots used to sell and may still sell like fans that was like 4 inches or so that ran on 120 they put out decent air and was cheap .but i think there noisy perhaps

gadget_lover said:

Wow. That's impressive. What kind of PC did you have in there? Where did you find power supply that required no cooling?

Daniel

Click to expand...

You can find lots like this, pc104, mini-itx, etc.
I have a 500mhz fanless mini-itx than runs from 12v in sits in a tiny box and doesn't overheat even when sitting in the cab of my truck all day long.

Ahhh, a micro PC with operating spec to 60C (140F) . That makes more sense. I found pc104 systems that runs on only a few watts (a 386 proccessor took only 1.5 watts)

For some reason I envisioned a standard Pentium based PC and power supply burning a few hundred watts with 2 or 3 sq feet of sheet metal to act as a solar collector.

Daniel

It could be a full blown pc, I was just giving examples.