Mobile phone Logic Board and IC Testing/Troubleshooting.

[ShadyK]

Hi guys..

Its just me again.  i have a quick question really,  I am into mobile phone repair as a hobby mainly and im really getting interested in electronic as a whole,  The thing is if i was to test ICs and other components on a mobile phone?? What types of tools will i need i know it takes a lot of practise to be able to test ICs thats just from a quick search on google.  But hey every one has to start some where .  Thanks alot for help in previous post and i hope someone can help me today. 

[Jon86]

Depends a lot on what you want to test. There's not really any generic tool that you can just pop on a chip and see if it's working.
Say if you want to test an opamp, you'll have to put it into a specific test circuit. It's a lot more complicated than you think.
Also, with some ICs you just can't test them, it's virtually impossible. Most of the time you'll just have to power it up, probe some pins with a scope, test rails, and then narrow it down. Then you'll just have to guess what needs replacing.
If you just want to test components, you'll need a good multimeter and LCR meter. If you want to do anything more, really you'll need a good digital scope, and a really good understanding of the system you're working with.

[PA4TIM]

The most important tool is your mind !! Modern smart phones are very complex. You need to know a lot about digital electronics, RF and analog electronics and have a more then avarage knowledge. It is also very small. If you ask how to test "an IC" then I think you have a whole lot to learn. You can not test an opamp the same way as a microprocessor.

Needed: An EE degree,service manuals,  stereo microscoop, ESD gear, fast LA with the right protocols and tools to hook it up, very fast scope with miniature probes, a spectrum analyser with enough bandwidth if the problem is in the RF part (calling, bluetooth and wifi).

[abyrvalg]

PA4TIM, try infiltrating some local mobile repair shop's back office - and you'll see a chinese hot air station, some "42-in-1" phone programmer box and salvaged ICs for swap-testing.
We had a parts/tools supply business and we never sold a GSM spectrum analyzer, but service shops were happy to rent it for a week to pass manufacturer's certification and bring it back then

Vast majority of cell phone repairs is done on a principle "if you observe symptom X - replace part Y" (that's what official phone service manuals are about - diagrams of symptoms, simple measurements like "voltage at TP406 is 1.2-1.4V" and replacement targets). Just imagine how much it will cost to repair a phone if that will involve i.e. sniffing a HSIC link between CPU and modem with 1Gs/s LA

ShadyK, I would recommend reading some dedicated phone repair forum like forum.gsmhosting.com

[ShadyK]

Thanks guys,  Yeah i was just wondering what type of things i would have to do because currently i am sorting the funding out to go to school for EE,  Im only pretty young ya see soo.  And also like i said i am a complete novice when it comes to electronics but i have a keen mind and plan to really get into it.  But its knowing where to start.  Im more of a hands on person thats why i wondered about the mobile side of it because i can quiet easily repair mobile phones cosmetics and some board problems. But i feel like i could take it further. Thank you for the replys and the advice, So heres my next question for some one who is starting out like me where would you guys recomend? or what would you guys recomend doing to start?. as it seems i have a mountain ahead of me

[amyk]

where would you guys recomend? or what would you guys recomend doing to start?. as it seems i have a mountain ahead of me

Learn Chinese and visit places like Shenzhen's markets, I've seen them selling books on repairing mobiles (in Chinese, of course) and related paraphernalia. (The situation for repair tends to be a lot better there since a lot of the no-name/shanzhai handsets are built around the same chipset designs and components, instead of the more custom parts in "foreign" phones.)

[PA4TIM]

I do not know any mobile Phone repairshop, in fact I had no clue things like that exist. I never have bought a Phone, I get it free with my mobile Phone provider contract and it is insured. If it has a problem I contact the provider, they collect it and send a new one or repair my Phone. I have no clue about the repair department and it will not be some vaque back office.

But I know what you mean about swapping parts and boards, however that is something different as the TS asked, he wants to testi IC's, and in my opinion that is component level repair and not board swapping.

[ShadyK]

Yeh i understand that it can be pretty hard and most of it will be guess work . It was mainly changing backlight ics and coils. And flex connectors but i guess you already no about whats wrong so no need to test i guess.

[SArepairman]

I love repair stuff sometimes, because it can be so bootleg. For instance tapping on a board while you are working on it to see if it works (at least momentarily), this could indicate a broken solder trace or joint some where.

But repairing a cell phone seems like a nightmarish task. They are so small and everything is glued together... a cell phone would probably go flying out the window of my "shop" promptly.