iPhone 3GS PMIC Gets hot, Powers on, Will not charge

[switch998]

I got this iphone from ebay from the original owner. It was an impulse buy, since I usually only repair water damaged phones.

Anyway, the phone's original battery was drained, so it wouldn't power on. I swapped out a good board into the housing and let the battery charge. Everything works; dock conn, power button, etc... The bad board was put back in the case and it booted.

I plugged it into a wall charger, and the phone showed that the battery was charging, but it was actually still draining at an incredibly fast rate. The battery lasts just under an hour. I tested the fuse, and it is passing power. When the phone is plugged in without the battery, it will not enter the boot loop like other phones.

The PMIC is burning hot to the touch, and is probably shorted. The battery will drain when the phone is off as well. I just want to know what my solutions are. Should I reflow or reball, if I should what are some good profiles?

[ocnop]

You must change PMIC, standard fault when using non-original chargers.

regards,

[switch998]

ok great, do you know where is a good place to buy one?

[ham_sang]

i got a same problem but the ic has underfilled on it.How to remove it safely ?

Any tricks ?

BR

[chapster]

I haven't yet removed an IC with epoxy around it, or under it, but watching youtube videos, it seems a case of treating it like any other surface-mount chip and heating it up to melt the solder, but then prying it up gently with a small lever, like a screwdriver. Other videos then show the epoxy being heated up to around 150C, and then scraped off the PCB.

Looks like my 3GS has this failure of the power management IC (getting hot, draining battery in just over an hour, showing it's charging but battery still draining), so I may have to try replacing it. Trouble is, web searches show the chip only being available from the US or China, and costing around $50 (just over £30) new. With postage, makes me wonder if it'd be better to sell 3GS as faulty on eBay and buy a working one for only a bit more.

Don't suppose anyone on here repairs this fault, has lots of ICs and wishes to sell one or two?

[maui_1856]

better you takeout the bettery so that it wont damage other ic's.. That's my experience so far...


BR

[chapster]

Originally Posted by maui_1856

better you takeout the bettery so that it wont damage other ic's.. That's my experience so far...
BR

What other ICs have you found it damages, and have you replaced them all in the past to get a fully functional phone again?

Where do you buy the 338S0768 ICs from?

Although I have a hot-air soldering station, I'm still learning the best methods to use with BGA and other surface mount ICs. With this tiny power IC, what temperature do you use to effectively melt all solder connections? I've removed a few small BGA packages, but never any with epoxy underfill. I can buy the power IC stencil and use my solder paste to form pads on a new IC, I just don't want to pay too much for the IC itself since the 3GS is losing value now the iPhone 4 is out.