cooling and more memory?

Any technical questions about the Epiphany chip and Parallella HW Platform.

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Re: cooling and more memory?

Postby 9600 » Sun May 11, 2014 6:59 pm

AlbertoGP wrote:It would rest on the Zynq, Epiphany, and the HDMI chip, and be kept in place with a custom clip hooked at TP12, TP13, TP14 or maybe at the card edges, whatever works better when I try it out.
Is there any obvious problem with this?


I can't see one and Adapteva have been doing tests with an oversize heatsink and no fan, but I guess you'd need to try it out.

Cheers,

Andrew
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Re: cooling and more memory?

Postby AlbertoGP » Mon May 12, 2014 8:11 am

Great! That's exactly what I want!

That still requires removing the caps. The other alternative I've considered is putting aluminium risers above each chip and the heatsink on top, to clear the caps; I think it would be easier than cutting/drilling the heatsink.
I'll do that if we don't get more information about the cap removal possibility.

Cheers,
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Re: cooling and more memory?

Postby ZenoArrow » Tue May 13, 2014 11:27 pm

Fitted the AB Open Parallella case this evening, would recommend it for non-cluster Parallella setups (note the built-in fan):
http://shop.abopen.com/
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Re: cooling and more memory?

Postby AlbertoGP » Tue May 27, 2014 9:19 pm

I gave it a try without removing the capacitor; instead I drilled a well for it in the base of the heatsink and covered its sides with tape to avoid shorting the capacitor if it slides sideways.

heatsink-alignment.jpg
That hole is exactly in the right place. If it was around twice as big I could have used the standard clip, but anyway there is no hole for the opposite side of the heatsink.
heatsink-alignment.jpg (52.61 KiB) Viewed 11856 times

heatsink-general-view.jpg
heatsink-general-view.jpg (91.03 KiB) Viewed 11856 times

heatsink-clip.jpg
You can see the capacitor peeking from under the heatsink in between the other two. The clip is held in place by pressure from the top cover.
heatsink-clip.jpg (56.16 KiB) Viewed 11856 times


The result is not great. It still needs a fan which brings down the temperature immediately as you switch it on.

My advice is not to bother until next version when the caps go away, just use a fan in this one.
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Re: cooling and more memory?

Postby greytery » Tue May 27, 2014 10:30 pm

Gold Standard!! :P

(Just need a Parallella sticker to fit on top).

tery
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Re: cooling and more memory?

Postby shodruk » Wed May 28, 2014 3:27 pm

Great! :o
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Re: cooling and more memory?

Postby AlbertoGP » Fri Jun 06, 2014 5:09 pm

I've removed that heatsink, just realizing that I should have paid attention to the thermal image from the Kickstarter page:
https://www.kickstarter.com/projects/ad ... sts/703717

You can see that there are two small chips north and south of the Epiphany that get quite hot, and one of them was under the heatsink without touching it. I have the fan blowing from that side so some air was getting there, but I suspect that it was worse than having the whole area open with the air flowing freely over it.
The image I had in mind was this other one, but it's for the Gen0 board, not the Gen1:
http://s.radar.oreilly.com/wp-files/8/2 ... 00x232.jpg

I might have been transferring heat from the ZINQ to the Epiphany, which is probably as bad an idea as it sounds.

There is another problem: the ZINQ chip is slightly taller than the Epiphany. I had adjusted it with a piece of aluminium foil slightly thicker than the kind used for packaging food, plus a thin layer of Arctic MX-2 thermal grease, but then the HDMI chip is again a little bit taller than the ZINQ, so there is no way to have it completely level unless you start piling risers or thermal pads.
(Edit: ZYNQ and Epiphany are level as far as I can see. The one tilting the old heatsink was the HDMI chip)

I've put now a different heatsink similar to the original but 20x30x30mm big that rests only on the ZINQ and touches the back of the Ethernet plug. The temperature with the same fan on, but without the top side because it won't fit, is a couple of degrees lower: 45C to 43C. I don't know the ambient temperature but it's a warm day.

With the fan blowing I can touch the Epiphany without issue, it feels hot but it's no problem keeping the fingertip on it even after it has been computing things for a while.

So again, if you are thinking about doing this, don't. :-)
Last edited by AlbertoGP on Mon Jun 09, 2014 7:25 am, edited 1 time in total.
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Re: cooling and more memory?

Postby timpart » Sat Jun 07, 2014 12:43 pm

AlbertoGP wrote:It would rest on the Zynq, Epiphany, and the HDMI chip, and be kept in place with a custom clip hooked at TP12, TP13, TP14 or maybe at the card edges, whatever works better when I try it out.
Is there any obvious problem with this?

Rather late I've just spotted an issue. Don't use anything conductive that could short TP13 at 1.0 Volts to TP12 and TP14 at ground.
Incidently the parallela_gen1_schematic has two versions available on the website called revision 1. The one dated July 03 2013 is out of date and shows all test points being ground. The one dated August 06 2013 seems to be correct. At least the test point voltages match those I've measured on my board. (TP15 is 5.0 V)

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Re: cooling and more memory?

Postby aolofsson » Sat Jun 07, 2014 2:00 pm

Can you send the link to the old schematic. I thought we had purged all old copies.
Thanks,
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Re: cooling and more memory?

Postby aolofsson » Sat Jun 07, 2014 2:05 pm

The most up to date schematic is at parallella.org/docs and is dated Jan 2nd 2014.(except for first sheet which is labeled Dec 30th, 2013)
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