Cleaned water damage, no touch
Cleaned the phone with the ultrasonic bath. It came back, except touch doesn't work. I'm new to microsoldering, so I'm unsure what's wrong here. Is it touch ic?
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I can see a lot of burnt components below the touch IC, I've seen a few boards that had corrosion under the IC but since you gave it a ultrasonic bath I don't think it's that. Replace those components with hot air and some flux. Try and see if it works :)
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I'm nervous cause this would be like my first real microsoldering job. I already brought it half back, don't wanna make it worse
I've never soldered before, but I got a soldering iron for Christmas and it doesn't seem to hard. Be confident. Just remove the old chip, and solder the new one. Simple. Easy. Done.
Haha. I've found its much (doh! Meant to say) more difficult said than done
Do it! Do it! Do it!
Haha. This kid <3
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1st iMedic you must learn the schematics and use common sense. the touch circuit has two IC's the 1st being a driver the second being a trackpad. before you join many in randomly pulling IC's off the board with no clue what you are doing i would suggest you start with the power supplies first to the driver as the trackpad is controlled by the driver so no driver then no voltage. all water damaged devices fail when buck rails short as these are high ampere rails. low ampere rails or LDO's rarely fail. the touch has a high voltage line 17v through the inductor coil and this must be the 1st place to check as it is a flyback generator. if you have pp voltages present at the driver and trackpad then consider replacing the driver then trackpad. to reball a water damaged device is nonsensical as the water damage is usually a short within the IC. the only thing you should ever reball is the parts that are non replaceable. the modem and cpu. if you reball you can not be certain you have eliminated a possible cause. the only way to do this is to replace. to avoid pop corning the cpu (blowing the balls) then recreate a temperature profile by bringing the board up to heat gradually and heating the ic for no longer than 10 seconds in one spell. keep a temperature profile that is gradual until the ic releases and you won't go wrong
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Ok. Thanks for the input. Which one is the driver? I checked all the capacitors around the touch ic, and found three of them to be very high, and then tested another known good board. The three capacitors are running 160-171 ohms. Also I believe that I knocked loose some of the solder joints on the cpu, and believe I need to reball that for sure. The capacitors hopefully will be reasonably simple to replace
on the i6 the driver is below the trackpad ic. and above the pmu
U2401 (Cumulus) resistance varies the only true way is test the voltage supplies from LCD PMU (Chestnut) and wake voltage pp1v8. when chasing faults always start at the source PMU supply of that circuit. if you have heard popping then you will have overheated the board.
good luck and keep practicing
13 Comments
I would say practice on a dead board first, then get a donor board and take the components from it. Also there are burnt components next to the PMIC.
by Gigabit87898
Been practicing. This is for reals. Hence the nervousness
by iMedic
@theimedic how did it go? Touch resolved?
by Gigabit87898
@gigabit87898 No, I decided to reflow the chips first, now it doesn't come on at all, and gets hot on the top front of the board
by iMedic
Sounds like a short on the main power line from the battery connector. May want to check continuity along the main line. Did you op check the phone after ultrasonic cleaning with a new screen? Just wondering because typically the screen and charging port does not make it. If they do service they do not work properly.
by Mark Prince
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