EEVblog #321 - Google Nexus 7 Tablet Teardown - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: July 24, 2012, 02:38:33 pm
content: Dave.

author: hans
author_rank: Super Contributor
timestamp: July 24, 2012, 02:59:29 pm
content: 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 accuracyI 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 existsOh, 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.

author: Stephen Hill
author_rank: Regular Contributor
timestamp: July 24, 2012, 03:50:15 pm
content: 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/1177Datasheet:http://datasheets.maxim-ic.com/en/ds/MAX774-MAX776.pdfBut 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...

author: free_electron
author_rank: Super Contributor
timestamp: July 24, 2012, 06:32:21 pm
content: 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

author: SeanB
author_rank: Super Contributor
timestamp: July 24, 2012, 06:42:59 pm
content: I will guess the cutout with nothing in it in the top is for the rear facing camera in the REV2 version.

author: M. András
author_rank: Super Contributor
timestamp: July 24, 2012, 08:23:14 pm
content: 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

author: T4P
author_rank: Super Contributor
timestamp: July 24, 2012, 08:36:20 pm
content: My first smartphone was a Asus P320 and clearly they still keep the same sensible all-out circuit design that they did!Quote from: M. András on July 24, 2012, 08:23:14 pmYes, 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

author: Stephen Hill
author_rank: Regular Contributor
timestamp: July 24, 2012, 09:46:37 pm
content: 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!

author: KAlSi3O8
author_rank: Newbie
timestamp: July 24, 2012, 10:58:09 pm
content: 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.

author: EEVblog
author_rank: Unknown
timestamp: July 25, 2012, 01:02:44 am
content: 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.

author: Monkeh
author_rank: Super Contributor
timestamp: July 25, 2012, 01:23:40 am
content: Quote from: EEVblog on July 25, 2012, 01:02:44 amProbably 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.

author: IanB
author_rank: Super Contributor
timestamp: July 25, 2012, 02:34:06 am
content: Quote from: Monkeh on July 25, 2012, 01:23:40 amCan 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...

author: Monkeh
author_rank: Super Contributor
timestamp: July 25, 2012, 02:58:38 am
content: Quote from: IanB on July 25, 2012, 02:34:06 amThey're aware of the issue. It's flaky, sometimes you can, sometimes you can't.

author: IanB
author_rank: Super Contributor
timestamp: July 25, 2012, 03:06:13 am
content: Quote from: Monkeh on July 25, 2012, 02:58:38 amAlways I can't.

author: SeanB
author_rank: Super Contributor
timestamp: July 25, 2012, 04:47:15 am
content: I do not have that problem ( touches wood/head) as the commens always work for me.

author: Monkeh
author_rank: Super Contributor
timestamp: July 25, 2012, 12:26:22 pm
content: Quote from: IanB on July 25, 2012, 03:06:13 amTry setting a channel image on Youtube.

author: Yvan Rodrigues
author_rank: Newbie
timestamp: July 25, 2012, 02:52:00 pm
content: 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?

author: M. András
author_rank: Super Contributor
timestamp: July 25, 2012, 03:02:34 pm
content: Quote from: Stephen Hill on July 24, 2012, 09:46:37 pmcopper 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

author: poorchava
author_rank: Super Contributor
timestamp: July 25, 2012, 04:03:17 pm
content: 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).

author: Stephen Hill
author_rank: Regular Contributor
timestamp: July 25, 2012, 04:05:41 pm
content: Quote from: poorchava on July 25, 2012, 04:03:17 pm8GB = £159.0016GB = £199.00

author: kodi
author_rank: Contributor
timestamp: July 25, 2012, 06:38:20 pm
content: 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

author: Nebby
author_rank: Newbie
timestamp: July 25, 2012, 08:58:11 pm
content: Quote from: Yvan Rodrigues on July 25, 2012, 02:52:00 pmAluminum 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.

author: T4P
author_rank: Super Contributor
timestamp: July 26, 2012, 08:33:34 am
content: Quote from: poorchava on July 25, 2012, 04:03:17 pmANDDDD... So the 400pound ( about there, at least 1k here ) iPad is even more not acceptable for a TOY/gadget!

author: ejeffrey
author_rank: Super Contributor
timestamp: July 26, 2012, 09:49:56 am
content: Quote from: Nebby on July 25, 2012, 08:58:11 pmAluminum 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.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: July 26, 2012, 08:17:05 pm
content: Quote from: EEVblog on July 25, 2012, 01:02:44 amMaybe you could get an attractive female Aussie assistant.I bet your views will go up.

author: Kashif
author_rank: Contributor
timestamp: July 28, 2012, 01:07:23 am
content: Hi Dave,Is audio coming from the processor through a external amp or does speakers have some dedicated codec chip?Thanks,Kashif

author: T4P
author_rank: Super Contributor
timestamp: July 28, 2012, 05:33:04 pm
content: Always a dedicated QFN/UFBGA codec+Class D chip, never straight.How the hell do you put out a digital signal straight i don't know!

author: TbayBoy
author_rank: Contributor
timestamp: July 30, 2012, 05:17:33 pm
content: Quote from: SeanB on July 24, 2012, 06:42:59 pmMy guess also

author: LaurenceW
author_rank: Frequent Contributor
timestamp: July 30, 2012, 10:48:14 pm
content: Hmm - not sure I buy the "copper = heat-sink" argument. Consider this.It's a single cell lithium battery, so that's about 3.7V. The mAH rating was something like 4300, so that gives the cell a total energy storage of around 16 WHr. Now, if the device is slated to run for around 8 (or more) hours, it can only be drawing that energy at a rate - power - of 2 (or less) watts.That's the WHOLE device - processor, screen, backlight, memory, Wifi, audio, other devices, etc. It's hardly going to break out into a sweat at these power levels, is it?With a plastic back and tough EMI regulations, that copper is there to stop the tablet from interfering with grandma's AM radio.

author: saturation
author_rank: Super Contributor
timestamp: September 04, 2012, 12:43:19 pm
content: I got one of these as my first tablet, mostly to read pdfs. Its decent enough for older eyes, but its still easier on a bigger screen, like the iPad, which I do not own or will not buy because it doesn't give me control of the software or hardware like Android does.A great job with the tear down. Even with competitors doing similar tasks, eevblog's version has a unique flavor as you dig into the component level, while most stay at the board level.Here are some of the best:http://www.informationweek.com/byte/news/galleries/personal-tech/tablets/240003315http://www.isuppli.com/Teardowns/News/pages/Low-End-Google-Nexus-7-Carries-$157-BOM-Teardown-Reveals.aspxSome insights from all the non-eevblog teardowns:The BOM suggest the Nexus 7 is a loss leader, it costs more to make than its being sold.Given how fast things are going in the tablet market, Nexus 7 is essentially disposable. It will probably be obsolete in 1-2 years, way before the LiPo battery gives out. Nevertheless, its so easy to work with and modular that when used Nexus 7s hit eBay in a few years, it should be easy to repair with cannibalized parts, it would be worth it if a fresh battery is still around and economical to buy.The PSU has a load sensor, as drops charge rate if you use certain microUSB cables. Cables dedicated to charging, such as the OEM Motorola Droid cables are no problem, but some 3rd party cables I have reduce the current flow.Wifi supports n protocol, but no 5 GHz radio.Complaints on-line for US users with production hardware defects, estimating Amazon complaints its about 10-20%, rated 4/5 stars. The defects seem batch related, Amazon and Google Store has gotten a fair share, as Staples.com related sales have ne'er a complaint, and their market is not tech savvy either, rated 4.75 stars. Amazon and Staples have about a similar number of reviews, ~ 90.The defects are:battery = dies spontaneously, fail to charge after 1 week of use, and shows itself as erratic operation and unexplained shut downs with a full chargeglass panel separation = unit operates but causes clicking soundglass is not Gorilla glass, just 'Corning' glass. Some folks have shattered their screens when dropped yet online reviews show it resists cracking when dropped [ full youtube videos of iPads vs Nexus 7 being dropped from 3 feet] but will crack if the glass separates from the LCD.capacitive sensor attachment = loosens, leading to dead spots on the screen, squeezing the screen can correct the issuemic failure = fails to receive input after some timeAndroid OS is is 4.1.1 released 7/12 and is glitch free, so far. Install was as smooth as Dave showed it and effortless. Apps seem to be bug free.In toto, don't throw away the box for at least 12 months, to avail of the warranty. If you do buy one, buy it retail so its easier to return because the prices are actually much higher online, than retail!

author: T4P
author_rank: Super Contributor
timestamp: September 04, 2012, 06:31:26 pm
content: So your same "not gorilla" analogy speaks for Samsung's Crap SIII not being Gorilla II?

author: saturation
author_rank: Super Contributor
timestamp: September 04, 2012, 07:18:50 pm
content: I don't really know T4P, Corning has a site listing all Gorilla glass products, and most phones and pads I know using it rarely are reported broken. On some Nexus 7, the screen breaks somewhat easily. Nexus 7 is not listed on the Gorilla site, and confirms what other reviews suggest.http://www.corninggorillaglass.com/OTAH, there is this test:Quote from: T4P on September 04, 2012, 06:31:26 pm