EEVblog #321 - Google Nexus 7 Tablet Teardown

[EEVblog]

Dave.

[hans]

GLONASS is useful because the network is complete and supplies almost as much satellites as GPS. While you may receive 6 satellites from GPS at a specific moment, you may actually also receive additional 6 from GLONASS. Combined you have 12, so you get better accuracy I believe many receiver chips come with both frontend these days.

I have 'sat' behind some RTK DGPS receivers for days (project.. ) and with GPS+GLONASS I never saw it drop below 9 or 10 satellites in total. And that wasn't even in an open field (office with antenna on the roof)..

Funny, according to Maxim the MAX77612  doesn't even exists 

Oh, here is more:
http://www.ubmtechinsights.com/uploadedImages/Public_Website/Content_-_Primary/Teardowns/2012/Google_Nexus_7/google-nexus-7-comm-front.jpg (FRONT)
http://www.ubmtechinsights.com/uploadedImages/Public_Website/Content_-_Primary/Teardowns/2012/Google_Nexus_7/google-nexus-7-comm-back.jpg (BACK)
So indeed, FLASH and more SDRAM on the back, and the audio and display driver chipsets.

[Stephen Hill]

If you knock two digits off that Maxim part you get the MAX776 a -15V or Adjustable, High-Efficiency, Low IQ Inverting DC-to-DC Controller.

"Negative LCD Bias Supply Is Capable of Generating Very High Negative Voltages, Delivers Up to 1A"

Webpage: http://www.maxim-ic.com/datasheet/index.mvp/id/1177
Datasheet: http://datasheets.maxim-ic.com/en/ds/MAX774-MAX776.pdf

But the above part isn't available in a BGA package. So either MAX77612A is a completely different part or it's the above part in a BGA package.

Although I'm not sure why you would want a BGA package for a 8 pin device...

[free_electron]

in the power supply section you missed out the big flip chip device right off and below the inductors ( silvery chip )
that is actually a naked pieceof silicon with solder balls deposited straight on the die so it looks like a bga.

you don't see too manyoftose , unless in smartphones where integration is even tighter

[SeanB]

I will guess the cutout with nothing in it in the top is for the rear facing camera in the REV2 version.

[M. András]

i hope you pressed that copper foil back where it was and approx same places before you pulled it up, i bet it acts as heatsink on that tegra too not just emi shielding

[T4P]

My first smartphone was a Asus P320 and clearly they still keep the same sensible all-out circuit design that they did!

i hope you pressed that copper foil back where it was and approx same places before you pulled it up, i bet it acts as heatsink on that tegra too not just emi shielding

Yes, it's a heatsink too. since looking at the IHS on the tegra 3... it can draw quite a bit of power. Still not half as much as the outdated iPad 3

[Stephen Hill]

I'm not sure a thin piece of copper will do anything to cool the processor.

I would say it's there for sheilding and no other reason!

[KAlSi3O8]

The reason for the epoxy on the corners of the NVidia Tegra is that this is a mobile device and the Tegra is a BGA device. If the Nexus is shocked by dropping it, then the circuit board will flex and this plays havoc with BGAs by cracking its balls. I know I have had to change 1000s of em (very expensive parts). The physically weakest points of any BGA are the corners. This is because the corner balls there have the least support from the balls around it and so get the most stress. When I troubleshoot boards with BGAs the problems are most often with signals near the corners of the BGA parts. Second most likely are along the sides. I used to keep a notebook and track failures with drawings of the bad ball locations and it showed the significance of this problem. If the board is never shocked (in shipping or customers dropping it or whatever) the BGAs are very reliable. Anyway, the epoxy is to add support for those weak areas. I really hate BGAs in portable products though it depends on the mechanical design of the chassis and board mount positions. I wonder how well the epoxy method works.

[EEVblog]

I'm 4th on Youtube search for "Nexus 7 teardown" already, and 2nd for "google nexus 7 teardown", behind the iFixIt chick.
That search engine works quick...

Dave.

[Monkeh]

I'm 4th on Youtube search for "Nexus 7 teardown" already, and 2nd for "google nexus 7 teardown", behind the iFixIt chick.
That search engine works quick...

Dave.

Probably helps that a Google employee reshared my G+ post about the teardown internally less than ten minutes after I made it. Not just the engine which works fast.

[IanB]

Probably helps that a Google employee reshared my G+ post about the teardown internally less than ten minutes after I made it. Not just the engine which works fast.

Can you drop a hint that Google should fix the inability to reply to YouTube comments if you have a G+ account? That is getting old really fast...

[Monkeh]

Probably helps that a Google employee reshared my G+ post about the teardown internally less than ten minutes after I made it. Not just the engine which works fast.

Can you drop a hint that Google should fix the inability to reply to YouTube comments if you have a G+ account? That is getting old really fast...

They're aware of the issue. It's flaky, sometimes you can, sometimes you can't.

[IanB]

They're aware of the issue. It's flaky, sometimes you can, sometimes you can't.

Always I can't.

[SeanB]

I do not have that problem ( touches wood/head) as the commens always work for me.

[Monkeh]

They're aware of the issue. It's flaky, sometimes you can, sometimes you can't.

Always I can't.

Try setting a channel image on Youtube.

[Yvan Rodrigues]

I think the copper is for heat dissipation. If it were primarily for shielding, there are much cheaper alternatives, like aluminium.

What is the thing that looks like a mini-SD or SIM socket?

[M. András]

I'm not sure a thin piece of copper will do anything to cool the processor.

I would say it's there for sheilding and no other reason!

copper is pretty good heat conductor even in form of that 0.5mm foil that mobile tegra i doubt will generate that much heat what this huge copper foil couldnt handle, i bet the shell of the whole device is magnesium alloy too. so it will acts as a bigger heatsink

[poorchava]

I wonder's what's the retails price going to be when this thing hits mid-eastern europe. As far as i know in UK it's been priced at ~200-250 pounds for 16GB version retail. It closely approaches the price tag which is not acceptable for a TOY/gadget (let's face it - you can get full featured Asus/Acer netbook for that price).

[Stephen Hill]

I wonder's what's the retails price going to be when this thing hits mid-eastern europe. As far as i know in UK it's been priced at ~200-250 pounds for 16GB version retail. It closely approaches the price tag which is not acceptable for a TOY/gadget (let's face it - you can get full featured Asus/Acer netbook for that price).

8GB = £159.00
16GB = £199.00

[kodi]

and regarding lack of (micro)sd slot: http://www.engadget.com/2012/07/21/ultimate-hack-nexus-7-hooks-up-with-external-usb-storage-flopp/

Pity they dropped HDMI support. Pre production models had it: http://www.theverge.com/2012/6/27/3121016/google-nexus-7-by-asus-hands-on-pictures#3500070

[Nebby]

I think the copper is for heat dissipation. If it were primarily for shielding, there are much cheaper alternatives, like aluminium.

What is the thing that looks like a mini-SD or SIM socket?

Aluminum is a very poor shielding material, that's why you normally either see the steel can or copper foil shielding used. For an equivalent amount of shielding, you need a significantly thicker amount of aluminum when comparing against copper.

[T4P]

I wonder's what's the retails price going to be when this thing hits mid-eastern europe. As far as i know in UK it's been priced at ~200-250 pounds for 16GB version retail. It closely approaches the price tag which is not acceptable for a TOY/gadget (let's face it - you can get full featured Asus/Acer netbook for that price).

ANDDDD... So the 400pound ( about there, at least 1k here ) iPad is even more not acceptable for a TOY/gadget!

[ejeffrey]

Aluminum is a very poor shielding material, that's why you normally either see the steel can or copper foil shielding used. For an equivalent amount of shielding, you need a significantly thicker amount of aluminum when comparing against copper.

Aluminum is a perfectly cromulent shielding material.  It does need to be slightly thicker than the equivalent in copper but not by much.  Neither work well at screening low-frequency magnetic fields which is why steel cans are preferred for shielding SMPS transformers.  The problem with aluminum as a screening material is the formation of the insulating oxide layer which makes it hard to make reliable electrical contact.  With copper you can just push a bronze spring contact against the shield or solder directly to it.  With aluminum you need to either scrape it with something that breaks through the oxide layer (easy to do on a die cast case, but hard to do on a thin foil) or spot-weld contacts to it.

[timelessbeing]

I'm 4th on Youtube search for "Nexus 7 teardown" already, and 2nd for "google nexus 7 teardown", behind the iFixIt chick.
That search engine works quick...

Dave.

Maybe you could get an attractive female Aussie assistant.  I bet your views will go up.