EEVblog #514 - $5 Mobile Phone Teardown - LG800G - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: September 03, 2013, 11:21:03 pm
content: What's inside a modern bare bones $5 mobile phone?The LG800G available from Tracphone for $5:http://www.tracfone-orders.com/bpdirect/tracfone/PhoneDetails.do?action=view&productVariantExtensionId=23192218Datasheets:http://www.infineon.com/dgdl/X-GOLD_213-pb.pdf?folderId=db3a304312fcb1bc0113000c158f0004&fileId=db3a30431ddc9372011e1fc7f7fd413dhttp://www.rfmd.com/CS/Documents/7161DS.pdfhttp://en.wikipedia.org/wiki/High-electron-mobility_transistorhttp://www.broadcom.com/products/Bluetooth/Bluetooth-RF-Silicon-and-Software-Solutions/BCM2070

author: marshallh
author_rank: Unknown
timestamp: September 03, 2013, 11:49:38 pm
content: IIRC the bga underfill is for shock protection (don't want the packages to shear off under excessive G's) and moisture/residue contamination. It will also inhibit tin whisker growth but I doubt that was a design concern.

author: Lukas
author_rank: Frequent Contributor
timestamp: September 04, 2013, 12:22:19 am
content: The golden can at 6:35 is much more likely to be a (MEMS) microphone than a filter.

author: ivan747
author_rank: Super Contributor
timestamp: September 04, 2013, 02:16:04 am
content: Very interesting video. The phone was more bare-bones than I thought it would be. It seems like with these SOCs evryone could design a cellphone (if you manage to get sent samples!).I'm curious about the antenna. It resembles nothing you can see on textbooks. It seems to me that both antennas seem lossy and very far of ideal. The GSM antenna is divided in sections, which reminds me of yagi antennas, is that it? The bluetooth one seemed undersized, I don't even think that was quarter wavelength. I also guess using a chip antenna (they are fractal antennas the size of an SMT resistor) was more expensive than making the plastic spacers hold some cheap metal film.

author: Stonent
author_rank: Super Contributor
timestamp: September 04, 2013, 03:13:41 am
content: The antenna design resembles what they did on the old 7200 series blackberries. (When they were blue)

author: Stonent
author_rank: Super Contributor
timestamp: September 04, 2013, 03:15:08 am
content: Any chance of seeing if you can somehow drive the phone's LCD? I guess we'd need a data sheet though.

author: Corporate666
author_rank: Unknown
timestamp: September 04, 2013, 04:27:55 am
content: One want to take a wild ass guess at manufacturing cost for that phone?I have no experience in large volumes like they would be doing, but I would have to guess easily $20 or so.

author: Electr0nicus
author_rank: Regular Contributor
timestamp: September 04, 2013, 05:14:54 am
content: Quote from: Stonent on September 04, 2013, 03:15:08 amWhen you look at the connector at 7:40 in the video it's obvious that this display is driven using a parallel RGB Bus. The left 6 traces are likely the control signals. At least most displays use a minimum of 4 Signals (HSYNC, VSYNC, PCLK, DE). Depending on the manufacture there could be a few more signals, or there are some ground traces in between to improve signal quality. Then there are 16 thin traces in the middle of the connector. This is most likely the RGB data bus using a 5:6:5 arrangement (5Bits red, 6Bits green, 5Bits blue). The thicker traces on the right side of the connector are most likely traces for power and backlight.

author: BravoV
author_rank: Super Contributor
timestamp: September 04, 2013, 05:57:37 am
content: Dave, I think its safe to assume that now you know (for sure ?) at least one, who is contributed thumb downs at your videos.Don't know, but looks like it has nothing to do with the content anymore, and becoming its personal ? Related post ->HERE

author: Stonent
author_rank: Super Contributor
timestamp: September 04, 2013, 06:02:41 am
content: Quote from: Electr0nicus on September 04, 2013, 05:14:54 amOh yeah, obviously, of course.

author: oakkar7
author_rank: Contributor
timestamp: September 04, 2013, 06:07:15 am
content: Quote from: Corporate666 on September 04, 2013, 04:27:55 amI agree with Corporate666 guess, $20.Here is Bunnie houng blog post china cheapo phone. It's not a advanced touch semi smart phone but very basic bare phone. The difference between these two phones is that china's The $12 Gongkai phone is real manufacturing cost.http://www.bunniestudios.com/blog/?p=3040

author: EEVblog
author_rank: Unknown
timestamp: September 04, 2013, 06:13:18 am
content: Quote from: BravoV on September 04, 2013, 05:57:37 amIt's always personal with people who leave emotive comments. Which is fine of course, I like passion. But when people just keep complaining about the same thing thing over and over again, it gets very boring very quickly, for everyone. If he does it again I'll simply block him. Which will of course lead to inevitable accusations of not being able to handle any negative feedback

author: EEVblog
author_rank: Unknown
timestamp: September 04, 2013, 06:18:30 am
content: Quote from: Corporate666 on September 04, 2013, 04:27:55 amSomeone mentioned the LCD is an LG, and that's something to remember, LG are pretty big and make a lot of stuff, so the cost might be less than you might think.I reckon about $15-$20, but entirely depends on how you factor in the internal pricing in their own factories.

author: BravoV
author_rank: Super Contributor
timestamp: September 04, 2013, 06:19:25 am
content: Quote from: EEVblog on September 04, 2013, 06:13:18 amWell, in this particular issue, I'm suggesting just leave the judgment to "majority", and ignore those really low dB "noise".C'mon, you now this better, its not worth the effort ironing out a trivial few uV ripple at a 100 volt power supply rail.

author: EEVblog
author_rank: Unknown
timestamp: September 04, 2013, 06:34:36 am
content: Quote from: BravoV on September 04, 2013, 06:19:25 amI can do that, but I can't expect others to do the same. That means trolls like Anton lead to nasty debates in every video if allowed to continue.

author: moemoe
author_rank: Regular Contributor
timestamp: September 04, 2013, 07:37:44 am
content: When talking about "full size sim card", I think of the leftmost in this picture. You probably ment a mini-sim, contrary to micro- and nano-SIM.Image Source:http://en.wikipedia.org/wiki/File:GSM_SIM_card_evolution.svgCC-BY-SA

author: tinhead
author_rank: Super Contributor
timestamp: September 04, 2013, 08:27:00 am
content: Quote from: EEVblog on September 04, 2013, 06:18:30 amthat display (LM283DN1A) is know, see service manual from other phonehttp://diagramas.diagramasde.com/celulares/EN_LG-T325_SVC_ENG_101012%5Bup.by.nasirahmed%5D.pdfso it should be made by TOVIS. Interessting is that detail : RENESAS(R61520), that's the display controller.There is as well pinout of that display, so this could help a lot already.

author: LEECH666
author_rank: Frequent Contributor
timestamp: September 04, 2013, 09:28:15 am
content: That little logo in the middle of the LION battery looks a little bit (politically) inappropriate (at least for the German viewers) to me.

author: RupertGo
author_rank: Regular Contributor
timestamp: September 04, 2013, 09:49:15 am
content: Antennas in these things are pretty amazing things in their own right. when you think of the enormously variable RF environment they find themselves in and the large number of bands they have to cover. It's a long way from swaring up a K40 for hi band. (If you know what that means, you shouldn't.)I don't know if this is how LG does its antenna design (the Bluetooth one looks like a reasonably normal stub-matched radiator), but a lot of funky wprk has been done with evolutionary algorithms. Basically, you give the computer a set of mechanical and electromagnetic parameters and tell it to evolve the best design. It starts off with a very basic antenna, makes a series of random modifications, models them, picks the best result out of those, and repeats. NASA has done this with stipulations that the antenna must also be a structural part of another system, for example, stuff that classical antenna design techniques really can't tackle.The results can look really weird, but work really well.http://en.wikipedia.org/wiki/Evolved_antennais, as usual, a decent jumping-off point.

author: tinhead
author_rank: Super Contributor
timestamp: September 04, 2013, 10:11:51 am
content: Quote from: LEECH666 on September 04, 2013, 09:28:15 amno, there is no problem at all, oh well, maybe only for those who are a little bit dumb. Not only because swastika is something complettly differnt that you thinkhttp://de.wikipedia.org/wiki/Swastikabut as well from (nazi) historical point of view there is nothing wrong with it - it is our history! Human being are like that, don't think too much, or you will find out that since 10000yrs the list of unnecessary wars was looong. My top 5 is:- the loss of knownledge due wars/fire/etc., e.g.http://de.wikipedia.org/wiki/B%C3%BCcherverluste_in_der_Sp%C3%A4tantike- 9/11 plains and (NIST) steel theoryand resulting irak war- all crusades- vietnam war- WWIIBut yeah, probably a dumb customs officer could confiscate that battrey

author: xrunner
author_rank: Super Contributor
timestamp: September 04, 2013, 12:53:23 pm
content: That cheap thing had an external ant connector - I've never had a cell phone that had an ext. ant. connection.

author: nathanpc
author_rank: Unknown
timestamp: September 04, 2013, 04:54:50 pm
content: Quote from: xrunner on September 04, 2013, 12:53:23 pmMost mobile phones have the external antenna jack, but it's usually hidden with a rubber cover.

author: gardner
author_rank: Regular Contributor
timestamp: September 04, 2013, 05:53:42 pm
content: Quote from: nathanpc on September 04, 2013, 04:54:50 pmI have seen similar looking jacks on other phones, buried inside the battery compartment or behind a rubber seal.I do not recognise the connector. Is it a standard or something specific manufacturer by manufacturer? Can you buy mating connectors from mouser or somewhere? What is the standard?Besides connection for car/base-station external aerial, another use might be for testing, to allow verification of the RF section during manufacturing -- especially full power output and high sensitivity. Doing those tests through pads might be too noisy.

author: Corporate666
author_rank: Unknown
timestamp: September 04, 2013, 07:32:28 pm
content: Quote from: RupertGo on September 04, 2013, 09:49:15 amThis is one of the great tid-bits of "I didn't know that!" type information that make this site great!

author: Grapsus
author_rank: Regular Contributor
timestamp: September 05, 2013, 07:02:54 pm
content: Very interesting tear down. Though I wouldn't say it is a "cheap ass" phone like the gonkai phone that someone pointed at previously. It's more an entry level phone for kids or people who don't care about apps. It even has a dedicated bluetooth chip !The small chip near the Intel flash surrounded by caps is probably a power manager, responsible for regulating different voltages and charging the lithium battery.The GSM antenna is pretty weird, I agree that it must come from some sort of optimization software to have the most isotropic radiation pattern possible. As for the fact that it's smaller than 1/4 wavelength, think of it as a patch antenna, because it's pretty far from being linear.

author: Stonent
author_rank: Super Contributor
timestamp: September 06, 2013, 08:33:16 pm
content: Here's an antenna from an old Blackberry 7230

author: amyk
author_rank: Super Contributor
timestamp: September 09, 2013, 09:10:17 am
content: Quote from: gardner on September 04, 2013, 05:53:42 pmMight beHirose U.FL.

author: GeezerWhiz
author_rank: Newbie
timestamp: April 11, 2015, 07:49:49 pm
content: On the subject of phone cost: For many years, I have found cell phone deals (for an "emergency" glove box phone) leaving me with lots of left over phones. This is by design. Thru Amazon, I found a site called ShopCellDealsDotCom for Tracfone service with the LG800. Thetotalcost for service is (I'm still using them) US$ 2.53/month, for an LG800 with one year of service included and triple time for life, and a 3 month/200 minute card. So, that's 15 months of service with 600 minutes, and a free (post paid) phone. I bought 4 of them, or 5 full years of cell service with 2400 minutes (40 hours voice/ 20 hours data) time (both are transferred when phone changes, so no losses). At the deal end, I have 4 phones with switcher off-line power supplies. One is kept complete for battery charging. The remaining 3 are chopped down until only a skinny plastic battery holder remains, which then go into small portable electronic projects I build. With the super cheap cell service, and 4 Lipo batteries I can use, I consider the LG800 phones to be totally free. This is the third time I have gone thru a gob of cheap phones (Nokia, then Motorola) and been left with Lipo batteries (and a charger) that would not be cheap to purchase, a nice freebie for projects!How can Lipo batteries with charger be cheaper than that?

author: ale500
author_rank: Frequent Contributor
timestamp: January 05, 2016, 04:03:07 pm
content: I know this is an old thread but I just saw this video, and Dave mentions the keypad "domes". Does someone knows a bit more about where can I buy like 40 pieces ? I found Snaptron as manufacturer but Digikey, Mouser or Farnell seem not to carry them.

author: bitwelder
author_rank: Super Contributor
timestamp: January 05, 2016, 06:06:54 pm
content: Quote from: ale500 on January 05, 2016, 04:03:07 pmSomething like these?http://www.aliexpress.com/item/100pcs-lot-ultra-slim-diameter-3mm-mobile-phone-key-keypad-switch-touch-metal-shrapnel-round-circle/32454582575.html

author: ale500
author_rank: Frequent Contributor
timestamp: January 06, 2016, 05:25:34 am
content: Yeah, exactly that. Good find, now why the other distributors don't carry them ?... o well.