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A phone came in that won't turn on. The battery was punctured and it smelled. After I plugged in a known good battery, charge port and screen and connecting it to a charger the amp draw is exactly zero. And sure enough C5202_rf says pp_vcc_main is not shorted to gnd. I don't know what to do next, what or where should I measure. I'm thinking it might be PMIC but I'm still fresh on board repair.
Any help is highly appreciated!
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YOu have to start at the beginning and check PP_BATT_VCC and then PP_VCC_MAIN (which you did) and PP5V0_USB. If those are not shorted and reading the proper voltage, then you move onto the PMIC and check the voltage rails it generates. Depending on what you find, it may be a PMIC issue or a downstream issue.
Start probing and get back to me by commenting on the answer.
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Thanks for answering!! batt and main are there, also usb through charge port (a bit low, 4.5V but I guess cable loss is acceptable)
PP3V0_NAND and PP1V8 are present. I believe PP_CPU was there but I would have to recheck that.. also I noticed a bit warm around tristar while probing. I was probing this with a known good battery since I don't have a bench supply, I'll try to go to a friend's store later to see if he can lend me his equipment. Also I'm working without boardview, only schematics so it takes me a lot of time to find stuff out
The boardviews are available on gsmhosting. Just search for "free zxw tool". You will need to download the free PADS viewer.
PP5V0_USB should measure 5V, there is no loss that should be considered. Keep probing the output rails from the PMIC to see if anything is amiss.
I just spoke to the client: he's a truck driver and uses a car charger with cheap cable all the time, I guess it'll be tristar then. Could it be tigris too? Should I change both? I read sometimes bad tigris can kill a new tristar
Focus on Tristar...
If you are comfortable doing the repair, you can replace them both at once even if you charge a bit more.
But in most cases it is just Tristar.
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I once had a similar problem with an iPhone 6 (not powering on, zero amps drawn). After I changed Tristar it was charging and powering on again.
Before working on the PMIC I would always try to change Tristar first as you already replaced the charging port (because of the zero amps over USB). How does the PMIC and Tristar area look? Any signs of liquid on the board?
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No damage on the board at all, the board looks pristine and never been touched before. Only physical damage on the battery itself (which still outputs voltage, too afraid to put it on another phone though) Question: wouldn't I be able to boot the phone with a known good battery and shorting out the Hold pin if tristar is the problem? Even tried the board on a completely working housing and it did not boot
I know that it will not turn on without Tigris (tested on iPhone 6). Without Tristar I haven’t tested since this is always the first chip I change when I have no power/no charging problems...
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