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VDD_BOOST short,sound ic removed,80mA

The phone was dead so i tried to charge it,500mA,but no signs of life,opened it and found 1A of load,without powering on, connecting to the battery port. found that U2301 was heating and i took it away,the short on VDD boost was still there,no amp drawing before power up but, when i powered it up, the audio ic was Hot,drawing 900mA. I took it away and now the short is still there but after power up is stuck on only 80mA,so i can’t find the short. What should i do?

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Did this happen after an audio IC repair? What IC’s did you remove? A hot IC doesn’t mean it has a short and now you have created a lot of variables.

The only IC you should have removed was the Audio IC as this problem would have happened after replacing it. But that would only be after checking the common cause of the 80mA draw after an audio IC repair which would be C1915 bridged to C2301 Sometimes this bridge is hard to see as it usually happens at the bottom of the cap.

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This happened after the audio ic beeing removed, how could i know u2301 wasn't shorted? I knew there was a short, i checked vdd boost and was short, so i serched for heat and i found only one ic,U2301, that's why i removed the first, after removing the first i saw a short after power up and it was the audio ic heating, and that's why i removed it;indeed now the line is short but there are no signs of heat, where was i mistaken? anyway i'll check c1915.

Thank you very much-!

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If you have a look at the schematics you will see that a short on the VDD-BOOST line no matter what component is shorted will have to travel through U2301, that’s why it is getting hot.

This short should be easy to trace. So you have U3101 off the board? If not remove it and re-check the line, if the short is still there inject 4V directly into that line and use thermal cam or freeze spray.

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thank you,you're so kind,i'll try it

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@fabry225 .... since you removed the ic, pull up the data sheet for it and see where the pin for vin and vout are. take your reading to ground on each side and see which side of the circuit the short is on. it will help narrow down the search field. if it is still getting hot, after you find which side to look, add some 99% isopropyl to the area that is getting hottest and see which component dries up first. this will point to the issue typically.

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i did find the hot parts with the isopropyl alcohol,but after removing the ics the short is still there,so i think it isn't an ic's problem,now i'm trying with injecting current directly on the rail but i don't know which voltage should VDD_BOOST be

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correct... the issue is still present, meaning it wasnt the ic. so, find the side of the ic the short is still on, resolder ic, plug back the charger and start again. without a schematic, injecting incorrect voltage will destroy your device. inject at the mains on the board with the listed voltage on the cord or listed on the battery. whats your model number.

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A1778,thank you so much for helping

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fabrizio benvenuti ....you ever test to see which side the of the chip the board was on?

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Hi, the chips were good and weren't shorted so il'reistall them after finding out which component is shorted

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Fabrizio Benvenuti will be eternally grateful.
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