# 721 Fan Always Running



## Big D (Aug 19, 2002)

I have had my 721 for about a week now and everything is settling in just fine with one exception, the fan. The fan runs nearly 24 hours a day, even in a cool room early in the mornings after the receiver has been off all night. This does not seem right, especially since I have heard the fan actually turn off a couple of times, only to turn back on later and the receiver was turned off the whole time! I have also noted that the hard drive continues to spin 24/7, never spins down, not even during the short intervals where the fan is off. It may be normal for the HD to spin continuously, but I can not believe the fan needs to be running when the unit is off and it is in a cool room. The noise level of the fan is enough to be very bothersome while trying to read the newspaper and drink my coffee in the mornings.

What is the fan doing with the other 721's out there? Does anyone else's fan run all the time? How noisy is your fan, mine is pretty loud. :shrug:


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## Nordug (Aug 6, 2002)

Mine does too. I think its just the nature of the beast.


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## James_F (Apr 23, 2002)

My brother puts his DirecTiVo behind glass doors. I personally don't hear the noise, I guess I'm just used to it. Its like the refrigerator... :shrug:


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## jerryyyyy (Jul 19, 2002)

Look down the list for some older posts. One person has successfully added a fan which cools better than the internal unit. I will do that when I get a small fan that I have ordered.

This text was dictated with Dragon NaturallySpeaking 6.1. Please excuse dictation errors.


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## Big D (Aug 19, 2002)

The fan was on again this morning when I got up, however it soon went off only to start back up about 1/2 hour later, weird. The ambient temperature of the room is only 70 degrees, no way a fan should be necessary to cool the unit. I wonder if the on/off setting of the fan is controlled by an electronic devise or if it has some control via firmware. If firmware is involved, perhaps the software engineers could adjust the temperature setting up to a more reasonable value in a future software load, say something around 90 degrees ambient instead of 70 degrees.

My other thoughts are looking into "adjusting" the fan noise as we did with the 8VSB module for the Echostar 6000 receiver. The 6000 fan runs 24/7 by design, never shutting off and is also rather annoying. Many folks placed a 30 ohm resister in line with the power lead of the fan that slowed it down to about 50% of it's normal speed, thus lowering the noise to tolerable levels. I have never heard of anyone that has had any trouble with their module after doing this, mine has worked flawlessly. I am not ready to open my brand new 721 just yet, but at some point, this fan noise is going to get the better of me I am sure. The other thought is to look into replacing the fan with one of the quieter units available for sale from electronics stores, that also has been done by some folks with the 8VSB module. Maybe jerryyyyy's idea of disconnecting the internal fan and using an external, much quiter, fan has merit.

Neither of these approaches would be necessary if the 721 design engineers had an appropriate on/off setting value to the fan, we can only hope that it is adjustable via firmware and they realize the current setting to far to conservative.

I would be interested in what your thoughts are on this, I can't be the only one that feels a fan running (actually cycling) in a 70 degree room in a poor design.


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## James_F (Apr 23, 2002)

> no way a fan should be necessary to cool the unit


Well if you remove the Hard Drive then there wouldn't be any heat. 

Look you don't have computers without fans, the 721 is essentially a computer, hence it has a fan. TiVos, UltimateTV and other PVRs have all had fans. Its the nature of the beasts.

I think the problem is that unlike DirecTiVo, you can't tell what the internal temp is. For all we know, the unit could be hotter than we think. That said, I can't remember when my TiVo fan wasn't running, so maybe its that fact that the fan goes on and off is why it bothers you.


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## Big D (Aug 19, 2002)

I understand the need for the fan and yes, all computers have fans, my issue is the value setting that the fan is running at. I have 3 computers in my home, all of them have a fan that cycles on when the room temperature rises to about 85 degrees, which would put the internal temperature inside the computer around 100 I would guess. This seems normal and necessary to me. If the fan on my 721 acted the same, I would be a happy camper, come on at say 85 or 90 degrees ambient and turn off when the temperature is lower. I did check the actual temperature at the 721 just in case something in my HT cabinet was causing heat, it was 72 degrees right in front of the 721 and the fan was running. 

Is your TiVo fan very loud, sounds like it does not bother you? If it is lost in the background noise in a reasonably quite room, it would be okay, but my fan is loud enough to be annoying while reading the paper and drinking coffee. It is very similar to a refrigerator running. Again, if it was necessary, then so be it, but cooling a unit that is sitting at 70 degrees makes no sense to me.


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## James_F (Apr 23, 2002)

My TiVo internal temp is 48 Celsius or 118 Fahrenheit. It says that the temp is normal. Remember it doesn't matter what the external temp is, its what the internal is. Until someone can take the temp with the case *on*, its hard to say if the fan is coming on too much. I would assume with the case on, the temp would go up. There is no way that your 721 has an internal temp less than 100 degrees.

Where is your PVR located, in a cabinet? On top of the TV/VCR? All those things will make the fan run more since the unit can't breath. I remember when the TiVo came out, people would raise the unit by putting the tops to film canisters so that air would flow under the unit where the air would enter the unit. It would cool the unit almost 5 degrees Celsius...


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## Big D (Aug 19, 2002)

Good point to check the inside temperature, I should have done that earlier. Although not the most controlled test I have ever done, I was able to insert an electronic temperature probe slightly into the case from the underside and from the back, got reading of about 91 degrees F, plus or minus. This would not be the readings right next to the hard drive or on the mother board, but it would not be that much higher there. This is well below the spec of hard drives and most electronic components of course, but what I think we need here is some additional opinions on this. My curiosity is not if a fan is needed (it is) or even if it should be running with 70 degree room temperature with an internal temp around 100, but more if other 721's are exhibiting the same behavior as mine and if Echostar has put to much cushion into the spec as to when the fan should turn on.


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## James_F (Apr 23, 2002)

Well someone needs to write a program that looks at the core temp and writes it to a text file. Then we'd know what kind of temps we are dealing with here....


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## jerryyyyy (Jul 19, 2002)

I like the idea of the resister. The wiring for the fan is quite accessible. The big heat producer is the power supply. The problem with adding the fan is how to mount it. There are lots of photos of these parts in previous posts.


Please ignore spelling errors. Dictated with Dragon Naturally Speaking 6.1 speech recognition software.


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## SParker (Apr 27, 2002)

looks good to me!


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## MarkA (Mar 23, 2002)

"Well if you remove the Hard Drive then there wouldn't be any heat."

The CPU is a major heat source, as are other silicon components.

Personally, I think an ideal design would be to use a super-quiet fan, and then maybe even have an option to slow it down to a low speed mode when the unit needs the fan, but doesn't need all the cooling power.


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## James_F (Apr 23, 2002)

Well Obviously Zac  

Look, you could use Notebook components, but that would increase the cost. People will pay a premium for a notebook, but not a PVR...


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## MarkA (Mar 23, 2002)

James, I think the silicon used in the PVR 721 already IS low power. If it's at all like the 501... I have yet to see a 721, it's fairly quiet. Certainly not like my computer, which due to my cooling system in it sounds like a jet engine taking off when I start it (okay, that's an exaggeration... but still...) Which is why I keep it located in such a way that I am unable to hear it well (of course, if I put it out in the open I'd likely need less cooling... But I figure I still come out ahead noise-wise. But it's hard to change a CD  !


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## James_F (Apr 23, 2002)

Check out what people are saying about DirecTiVos, noise and heat.

http://www.tivocommunity.com/tivo-vb/showthread.php?s=&threadid=71761


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## rj_in_ut (Aug 26, 2002)

This had to be one of the design compromises that the engineers who did the 721 hated the most. Four conflicting requirements:

1 Looks pretty sitting on a display rack at Best Buy
(sexy slim case - i.e., 20 - 30 cm diameter fan mounted
in a bad location [back of case])
2 Doesn't burn itself up within the first 90 days
3 Cheep to manufacture
4 Records 90+ hours of video.
(My 40GB Maxtor HDD puts out close to the same amount of
heat as a 20 Watt incadescent light bulb. I hate to think
what the big 100+ HDD in the 721 radiates!)

The key things that we must remember as PVR owners (I have a 501):

* The life of any electronic equipment is a direct function of its
operational temperature.
* As a Dish network customer, YOU OWN YOUR PVR! If it 
fails, you will have to pay to replace it. The longer it last,
the less the system cost you.

The cooler you keep your PVR (or TV/computer/vcr/stereo for that matter), the less often you will have to repair/replace it. The fan is your checkbooks best friend and your ears worst enemy.

My uneducated guess would be that the CPU has a temperature detection (thermal) diode in it (common in most modern CPU's) that is used to determining wether the fan is on or off.

If that guess is correct, one possible way to keep the fan turned off is to cool down the CPU.

If you don't mind "UGLY", (and you are ready to kiss off your warranty) one possible solution would be to:
1) Buy a 9cm diameter variable speed fan (a 9cm fan spinning 
at 1500rpm probably moves more air than the 721's small 
fan spinning at 7000rpm.... and makes next to no noise 
doing so!) from a computer store or an online vendor 
(such as newegg.com)
2) Tap off of the power connector going to the HDD with a 
standard computer power "Y" cable.
3) Drill a hole in the case of the 721 to feed through power 
wires to hook up the fan.
4) Glue (remember the UGLY theme) the fan to the outside of 
the case directly above the CPU (there are probably vents 
in the case in this location that would allow air-flow).

If you do mind "UGLY" AND don't mind spending money, a possible solution would be to find computer store that does "case mod's" and ask them to mount the fan for you. These guys usually have drill-presses, special sheet metal bits in the right sizes, and lots of black spray-paint. They may be able to mount the fan inside the 721's case in a way that both looks good and provides good air flow to critical components (CPU, HDD, and power supply in that order).

This type of work is quite common in the world of the "wealthy-lan-party" crowd. If you live in a big city, there is probably three or four shops who could do it for you at a reasonable cost.

Personally, I keep my PVR in the basement far away from the TV room. 40 feet of RG-6 and a UHF remote solved my fan noise problem over a year ago


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## Big D (Aug 19, 2002)

The "UGLY" approach does not apeal to me, I will just live with the noise I guess. I tried moving my unit to a different location in my HT cabinet and it does seem to be cycling the fan on and off some now, so it seems the 721 runs hotter then I initially thought and the fan is keeping it cooler to protect the electronics.

If anyone tries any fan modifications, let us know how it goes.


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