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Author Topic: GuruPlug Server Plus Heat Problems  (Read 134569 times)
thomasb
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« Reply #60 on: May 29, 2010, 08:13:37 PM »

There appears to be some confusion about failures in the two devices.

The bottom line is, both products are crap.  They were poorly designed, very poorly manufactured and even less tested.  It's like writing some software, fiddling with the code until it barely compiles (ignoring the warnings), run ("test") it to see if the copyright banner works and then market it and sell it.  Obviously it's going to be a disaster...
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tinker
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« Reply #61 on: May 29, 2010, 10:13:08 PM »

DembK50 and thomasb what make you such great authorities on the Sheevaplug? 
Dembk50 you admit you have never had one.  You will improve your credibility if you speak about what you have actual experience rather than using hear say.

I have been running a Sheevaplug for over a year with a USB hard drive hanging off of it with no heating problems and no power supply problems.  The Sheevaplug is barely above lukewarm temperature. 

Oh by the way there was a recent check in to u-boot for a fix to the way u-boot does reset of PHY chip.  It was not resetting it correctly. I have not applied that yet to see what difference, if any, it makes to the Guruplug temperature wise.

thomasb many electronic products in the USA have very short warranties. It is just one of the facts of life in the USA.
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dreamdreams
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« Reply #62 on: May 30, 2010, 06:08:44 AM »

I own both SheevaPlug and GuruPlug.

I didn't have heat problem with SheevaPlug.

But GuruPlug is different. It's much hotter when you touch it. Especially when you touch the metal on the rear. When I try to compile libtorrent debian package on it, it dies in the middle. I tried twice, got same 'hang and reboot' result.
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sfzhi
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« Reply #63 on: May 30, 2010, 06:57:00 AM »

Oh by the way there was a recent check in to u-boot for a fix to the way u-boot does reset of PHY chip.  It was not resetting it correctly.
Could you provide a link to that information? I suppose there are many people who would like to try that too.
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Lack of knowledge is not such a big problem, unwillingness to learn is.

fragfutter
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« Reply #64 on: May 30, 2010, 07:08:41 AM »

http://git.denx.de/?p=u-boot/u-boot-marvell.git;a=commit;h=375506ac8e975df8dab8aea42114651293cb963b
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DembK50
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« Reply #65 on: May 31, 2010, 06:52:29 AM »

You will improve your credibility if you speak about what you have actual experience rather than using hear say.
tinker, I'll take my lumps on Sheeva plug statements, since I've never owned one. It appears I was wrong, and I apologize for alluding to heat problems in the Sheeva plug. That's what I get for reading only a few unconfirmed posts on Sheeva.

I do have a guruplug, and can attest that it has huge heat problems. After leaving my huge heatstrap modified guruplug on for a number of days, it continued to get hot and then started to reboot. My next step is to add a fan to the setup. I'm totally disappointed with the guruplug, and will never buy a GlobalScale product again.
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hmetzger
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« Reply #66 on: May 31, 2010, 08:12:40 AM »

So I also voided my warrenty by opening it. After running for 10 mins the power supply is not hot at all, but the board is extremely hot. I can't hold it for a couple of seconds without being uncomfortable. I don't want to give up on the idea of a plug computer, I think its really cool, I just want one that runs cool. Someone mentioned that the next batch of guruplugs will be redesigned to be cooler, how did you hear this? Is there a link on globalscales website discussing this?
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thomasb
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« Reply #67 on: May 31, 2010, 08:43:52 AM »

DembK50 and thomasb what make you such great authorities on the Sheevaplug? 

The fact that the vast majority of owners are probably hanging out at message boards like this, and the incredible number of problems reported?  There's always going to be a few people who have a problem even if the product is really good, but to me it looks like there's quite a lot of people having these problems, and I don't think this is just a small fraction of people who own it.

thomasb many electronic products in the USA have very short warranties. It is just one of the facts of life in the USA.
30 days is quite rare, even here in the US.  90 days is much more common, but still indicates that the product usually is of inferior quality.  Better quality products are offered with 6 months or more, and good products typically have 1 year or more.  Haven't seen many products with only 30 days warranty here, sorry.
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willy
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« Reply #68 on: May 31, 2010, 12:25:35 PM »

So I also voided my warrenty by opening it. After running for 10 mins the power supply is not hot at all, but the board is extremely hot. I can't hold it for a couple of seconds without being uncomfortable.

I second this, I opened mine too and it's the same : the PSU is at room temperature but the board is absolutely untouchable, it really hurts. So my deduction is that when GlobalScale replaced the PSUs, their death was not the cause, but the consequence of a stupid thermal design which makes the CPU cook the PSU. The plug should have been thicker by 1-2 cm with a big heatsink in it and holes all around to let air flow inside. The design is globally bad, the 4 low-voltage wires as well as one primary wire broke after a few movements. This thing will certainly not replace my NSLU2, not to mention that it's even slower than my ALIX! I have a dozen of photos of the inside for those interested here : http://1wt.eu/articles/guruplug-slow-heater/.
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madman2003
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« Reply #69 on: May 31, 2010, 01:44:28 PM »

Assuming this is true, what would bring about this major change between the sheevaplug and the guruplug?

Ideally 205 mW extra for the sata port (worst case 410 mW if both are on). The extra NIC probably means an extra 700 mW (when loaded, but we have to assume the worst). Wifi/bluetooth is probably adds a few hundred mW too. So 1W of extra power isn't unlikely.

My *guess* is that the SoC runs at 1.7W in the sheevaplug, the memory probably contributes in the order of 1.5W, again a guess based on some random DDR2 datasheet i checked.

It's not unlikely that the sheevaplug heated up too, but how did it avoid getting warm/hot at the network plug?

EDIT: I now notice that the sheevaplug was stacked differently, the daughter board is between the main one and the psu, while for the guruplug the psu is next to the main board.
« Last Edit: May 31, 2010, 01:56:54 PM by madman2003 » Logged

fragfutter
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« Reply #70 on: May 31, 2010, 11:35:31 PM »

the sheevaplug has a larger heat spreader and it points to the outside of the case. The heatspreader of the gureplug is in the middle.
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stefba
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« Reply #71 on: June 01, 2010, 01:16:12 AM »

I did some quick measurements regarding the temperature in my GuruPlug. With closed case I could measure about 65C at the aluminium plate. So the junction temperature of the chips will be much higher. Too high! Just opening the case reduced the temperature to 45-50 C. Then I added a fan with heat sink (chipset cooler, size 50mmx50mmx15mm) on top of the aluminium plate. This reduced the temperature to 37-42 C.
The main cause for the heat issue is the stacked design of the PCBs. There is not much space between the aluminium plate and the PSU; 1-2mm. The hot air has no good chance to get outside the plug.
Applying a good heat sink to the plug is mandatory to avoid early damage. Furthermore there has to be a gap between the heat sink and the PSU to allow thermal convection. This may add 20-25 mm in height to the plug, but it will increase the reliability of it. I will post some photos when the changes to the plug are finished. This will take some time, I'm still looking for the most appropriate parts...
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superpat
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« Reply #72 on: June 01, 2010, 05:58:39 AM »

Hi,

There is still a lot of confusion regarding the Sheevaplug.

There were TWO hardware versions of the Sheevaplug.

The first had TWO pcbs  plus the power supply

The second known as V1.3  had only ONE pcb plus the power supply.  I am looking at mine dissembled in front of me at this moment.

I believe all the Sheeva's that have the failing power supply come from the second revision, (I may be wrong but I am 90% sure).  Therefore you CANNOT compare them to a two pcb GuruPlug, or  you cannot say "my Sheevaplug is perfect its lasted one+ years with no problems"....... WHICH version Sheevaplug are you talking about?

The problem with the failing power supplies are standard commercial quality capacitors, used in an application they might not survive.  SOME people may be lucky and receive a Sheevaplug with a capacitor in the power supply capable of lasting for years.   Other people have obviously received a  SheevaPlug with capacitors that fail after a few months.  I do not believe that the failure is directly related to the ambient temperature the Sheeva is in, although an ambient outside the GlobalSpace specified environment will not help reliability.

I have said before in many threads, the power supply failures are due capacitor failure due to electrolyte heating due to the capacitors having high ESR. A capacitor used in a switching power supply has to be designed for that role and have a defined low ESR and a tolerance for applied ripple currents and varying dc loads. A general purpose capacitor may or may not have a low ESR and be capable of working for extended periods in a switching power supply.

I have done some measurements on the SheavaPlug:-

Quote

I measured  using a Prism Electronics AIM 6451 LCR Databridge, the ESR's of the capacitors in my working Sheevaplug P.S.   The worst was the nominal 6.8ufd cap. This measured 5.9ufd on the bridge and the ESR  was measured at 19.78 ohm @ 100HZ.  I think my Plug power supply is about to die!

(Typically one would expect  approx 5ohm ESR.  For a sanity check,  I measured a spare 10ufd from my junk box, the ESR of this was 5.25ohm).

If the capacitor is supplying a varying DC load current, or a high ripple current, then a heating effect in the capacitor electrolyte occurs, proportional to the ESR.  watts= Iripple^2xESR.
 
I measured the internal temperature of the power supply using a thermocouple, (Tenma 72-6700 digital thermometer fitted with a remote type T thermocouple),  thermocouple positioned adjacent to the 6.8ufd capacitor.  The PS was closed up and the Sheevaplug restored to normal. I tested it on my workbench using the figure 8 mains lead. The Sheevaplug was standing on a wooden surface on it's rubber feet.

Ambient temp 17.5 deg C start, end 20.1 deg C  (central heating came on during tests)

1. Internal power supply temperature  start 17.5 deg C  end after 60 minutes running Meteoplug app on SD card (no hard drive )  60.8 deg C

2. Internal temp start 60.8 deg C,  end after 70 minutes running  500GB USB hard drive  powered from SheevaPlug constantly reading / writing 10GB file  71.6 deg C

I did not measure the temperature at the CPU or memory  packages. at the time I did the tests the power supply was the only thing I was interested in.



regards

Patrick



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fragfutter
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« Reply #73 on: June 01, 2010, 11:28:43 AM »

Oh, i didn't know that there was a sheevaplug with a sandwhich board.

back to the guruplug heat issue. I received my guruplug today and did my burn in tests Wink

Plug in power, nothing else. 15min idle. Feels warm but thats it.

Removing /etc/rc.local (and with this the wifi and the bluetooth module). Configure the network (gigbit). Sitting idle for 15 minutes. Warm but thats it.

Put some load on the CPU (endless loop that does md5sums of a 1MB file). Running for 15 minutes. Warmer. But i can still touch the Metal of the RJ45 connector.

Loading wifi modules. After five minutes i could not touch the connector any more. After ten i stopped the test (but it didn't reboot).

See also http://plugcomputer.org/plugforum/index.php?topic=1764.msg10688#msg10688


Looks like Heat is an issue. Using more then two features overloads the thermal design (feature = cpu, gigabit ethernet, wifi)
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alessio
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« Reply #74 on: June 01, 2010, 12:58:21 PM »

I made some shots of my GP with thermovision camera (Fluke Ti55).
Please find them attached to this post.

These are the conditions at which the shots were taken:
- GP was plugged in 230V @ 50 Hz for 15 minutes
- CPU was left idling !!
- Ethernet cable was plugged in eth0, but GP was not associated to the network
- 1 USB key was plugged in

As can be seen from the shots, the outside temperature of GP
was well above 60 C, exceeding 70 C on USNAP side.
That means that the inside temperature rises well above the reliable
operating point. (Commercial grade components, as used in GP,
are specified for 0-70 C range). I guess that the temperature of
the components inside GP could be in the range of 80-90 C. !!?!!

Unfortunatelly, I couldn't stress the CPU, because I forgot my JTAG
board at home. I also couldn't log in via SSH over Wifi, because I disabled
it previously. So, the situation has to be much worse with Wifi and BT enabled
and CPU doing some number crunching.


Those who have the problem with high temperatures of GP should really
consider adding additional fans or at least heat sinks. Otherwise, the GP
will be fried very soon... But, just to calm everybody down, GP will not catch
fire. It will just stop working with some melted components.

As an electronics engineer, I seriously wonder how could GlobalScale Tech. pass QA tests...

PS I posted a similar reply to NewIT forum.

Regards,
~Ale


* GP_bottom_view.jpg (21.99 KB, 760x480 - viewed 36551 times.)

* GP_connector_view.jpg (25.3 KB, 760x480 - viewed 35981 times.)

* GP_side_view_JTAG.jpg (21.93 KB, 760x480 - viewed 35879 times.)

* GP_side_view_USNAP.jpg (20.49 KB, 760x480 - viewed 35880 times.)
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