622 Freezes

[Smith P.]

My first thought was give you measures of heat sinks, materials of its, temperatures, etc and see how you'll calculate dissipating energy at PS, chips and HDD. But after dinner I came to conclusion you're as not experience PHD in PS design probably don't know - any EE will not make if power efficiency lower then 80%, actually it must be 85% min, actually we targeting 90-95%.

So, lets take worst case scenario - 85%; the DVR taking 50-55W ( measured ppl and posted here);
now, PS would radiate 5 to 7W; while one HDD (WD 320 GB) 5V * 0.65A + 12V * 0.9A = 3.25+10.8= 14.25W;
lets add BCM7038 and 2xBCM7411 -> I would estimate total as 15W + 2x7W eq ~30W.

And the balance between PS and other components will be 7W vs 40W.

Your turn now .

PS. I could go into detail measures and chip's characteristics, but it wouldn't be necessary for the place.

 

[OnYourOwn]

Wow, I'm impressed. Goal acheived, now lets get down to the nuts and bolts.

None of that is important because we have no control over it, unless you work for E*, then redo your calcs and fix it for us. The bottom line and what you need to focus on for the purpose of this board is it does not matter if 25 scfm will cool it to 135 or not, even if my hvac is set down to 67 degrees. There are too many variables such as case design to even try. You can calc all you want and what happens when the unit is in service is what happens.

Take for example how the lower case side is solid right next to the largest heat sink, such that the air flows right around it and not through it. There goes my 25 scfm calc. The bottom line for the purpose of this board is to throw air at it, it stays cooler, it does not reboot or reboots much less frequently depending on the heat damage. Then we wait for E* to do something about it.

Plus, it could be a batch of components that are bad on the power supply board or enough thermal goop was not used when attaching the heat sinks. Just way too many variables to even be suggesting your calcs.

Plus again, if you look at the revision history of the software updates you will see many reboot fixes in almost each version. Reboots have been a problam and they cannot seem to fix it yet. Possibly they need to cut some metal away from the case so the heat sinks get more air flow.

 

[Smith P.]

Major contributors ( are we going circles ? That old threads have a lot of info, BTW ) are the disk and BCM chips ( no heat sinks here - it was bad idea to remove them - other early models with same chips had them (!), plus DTV manufacturing own IRD/DVR with same BCM chips and use heat sinks).

So, back to your original suggestion about freezes by overheating a couple small heat-sinks in PS - it was not plausible assumption.

Root cause of the problem is complex of issues in a middle of the box: HDD, chips, bad air flow design and inefficient fan control.

 

[CDH]

No one is ingnorant in this world because everyone has their area of expertise.

That is certainly true, but mine is in a discipline far removed from engineering!

You will need to experiment, but I would try pulling the hot air up and out of the unit first.

I appologize for not providing wiring details. Electrical wiring is just too dangerous to provide those details here. I recommend getting an electrician friend that knows how to wire a 120V fan, if possible.

I'm wondering if the USB port on the back of the unit would provide power for a USB-powered fan, perhaps?

My hope is that Dish will (soon?) fix the software that controls the fan and then I can go back to not worrying about this at all.

Thanks for your help.

CDH.

 

[OnYourOwn]

Yes, the USB is powered (not sure if you must have the external drive enabled or not to get the power to it) and have heard people having success using it to drive a laptop cooler type fan set.

So true.

Thank you for the lesson. I always thought we should be putting heat sinks on the hard drives and not the power supply components.

Just got a new 722 and it will never get hot. She's running 89 avg with my supplemental cooling. So far so good, no reboots.

Thanks for the info and conversation.