Hi, this is my first time asking a question here, i'll be grateful if someone could answer some of this questions that i've been searching online for a days and just couldn't find the answer.[br]
[br]
To start with, i'm completely new to logic board level repairing after watching dozens of videos on youtube regarding the topic.
I apologize if there are any mistake i made since english is not my first language.[br]
[br]
To start this journey out of curiosity, i found this dirt cheap iPhone x (like a few bucks) on my local marketplace that's apparently won't boot. The owner stated that it happened after he attempting to replace the back glass by chiseling it, only noticing that the phone is dead right before assembling the new back glass. The metal housing is absolutely need a full replacement due to scratches and dents. Enough with the backstory, i want to focus more on the logic board[br]
[br]
The first thing i tried before hook up my crude power supply setup (which is just 4v 18650 battery and multimeter with current measurement), i notice that the battery rail which is PP_BATT_VCC line is shorted to ground. I tried measure the VDD_MAIN on the J5700 connect and find out the diode reading is around 0.25 (red to ground and black to vddmain), indicating that only battery line is shorted while the VDD_MAIN is... fine? I found online that diode reading for VDD_MAIN is around 355, i wonder if 0.25v is acceptable. I'm planning to check the capacitor near the battery connector first if there a short before attempting anything fancy. My usb microscope, proper power supply and some other stuff is still on its way, so i would like to ask few questions before it arrive.[br]
[br]
[br]
1. Normally, can you "inject" or plug in 4v directly to VDD_MAIN? I've seen another answer suggesting to "inject" 4v directly to VDD_MAIN to find the bad components, but i don't know much about it.[br]
[br]
2. With BATT_VCC is shorted, is it not a good idea to plug in 4v directly to VDD_MAIN, even if the VDD_MAIN itself is not shorted? Maybe it would cause a damage to the ic that is connected to both vdd_main and batt, like U3300?[br]
3. If i have a normal diode reading like the one that i found online, how much can it vary until it's considered too low or too high? With 0.355v for example, is 0.25v too low or it can be considered as normal, or acceptable?[br]
[br]
Additionally, maybe some general advice for a complete beginner like myself that is often hard to find on google?
[br]
Since this is my very first attempt to fix the board, i'm not expecting i'll be fixing this board and able to successfully boot it, but hopefully it does.
I apologize if this post is getting too long
Thanks!
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=== Update (01/06/24) ===
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For those who are wondering, this is the picture of the capacitor near the battery connector looks like. Sorry for low quality since it literally captured with telescope eye piece. Looks like something happened there
Hi, this is my first time asking a question here, i'll be grateful if someone could answer some of this questions that i've been searching online for a days and just couldn't find the answer.[br]
[br]
To start with, i'm completely new to logic board level repairing after watching dozens of videos on youtube regarding the topic.
I apologize if there are any mistake i made since english is not my first language.[br]
[br]
To start this journey out of curiosity, i found this dirt cheap iPhone x (like a few bucks) on my local marketplace that's apparently won't boot. The owner stated that it happened after he attempting to replace the back glass by chiseling it, only noticing that the phone is dead right before assembling the new back glass. The metal housing is absolutely need a full replacement due to scratches and dents. Enough with the backstory, i want to focus more on the logic board[br]
[br]
The first thing i tried before hook up my crude power supply setup (which is just 4v 18650 battery and multimeter with current measurement), i notice that the battery rail which is PP_BATT_VCC line is shorted to ground. I tried measure the VDD_MAIN on the J5700 connect and find out the diode reading is around 0.25 (red to ground and black to vddmain), indicating that only battery line is shorted while the VDD_MAIN is... fine? I found online that diode reading for VDD_MAIN is around 355, i wonder if 0.25v is acceptable. I'm planning to check the capacitor near the battery connector first if there a short before attempting anything fancy. My usb microscope, proper power supply and some other stuff is still on its way, so i would like to ask few questions before it arrive.[br]
[br]
[br]
1. Normally, can you "inject" or plug in 4v directly to VDD_MAIN? I've seen another answer suggesting to "inject" 4v directly to VDD_MAIN to find the bad components, but i don't know much about it.[br]
[br]
2. With BATT_VCC is shorted, is it not a good idea to plug in 4v directly to VDD_MAIN, even if the VDD_MAIN itself is not shorted? Maybe it would cause a damage to the ic that is connected to both vdd_main and batt, like U3300?[br]
+
3. If i have a normal diode reading like the one that i found online, how much can it vary until it's considered too low or too high? With 0.355v for example, is 0.25v too low or it can be considered as normal, or acceptable?[br]
-
[br]
-
4. This last question might sound silly, the diode reading of 355 that i found online, is it 0.355v or 3.55v?
+
[br]
Additionally, maybe some general advice for a complete beginner like myself that is often hard to find on google?
[br]
Since this is my very first attempt to fix the board, i'm not expecting i'll be fixing this board and able to successfully boot it, but hopefully it does.
Hi, this is my first time asking a question here, i'll be grateful if someone could answer some of this questions that i've been searching online for a days and just couldn't find the answer.[br]
[br]
To start with, i'm completely new to logic board level repairing after watching dozens of videos on youtube regarding the topic.
I apologize if there are any mistake i made since english is not my first language.[br]
[br]
To start this journey out of curiosity, i found this dirt cheap iPhone x (like a few bucks) on my local marketplace that's apparently won't boot. The owner stated that it happened after he attempting to replace the back glass by chiseling it, only noticing that the phone is dead right before assembling the new back glass. The metal housing is absolutely need a full replacement due to scratches and dents. Enough with the backstory, i want to focus more on the logic board[br]
[br]
The first thing i tried before hook up my crude power supply setup (which is just 4v 18650 battery and multimeter with current measurement), i notice that the battery rail which is PP_BATT_VCC line is shorted to ground. I tried measure the VDD_MAIN on the J5700 connect and find out the diode reading is around 0.25 (red to ground and black to vddmain), indicating that only battery line is shorted while the VDD_MAIN is... fine? I found online that diode reading for VDD_MAIN is around 355, i wonder if 0.25v is acceptable. I'm planning to check the capacitor near the battery connector first if there a short before attempting anything fancy. My usb microscope, proper power supply and some other stuff is still on its way, so i would like to ask few questions before it arrive.[br]
[br]
[br]
1. Normally, can you "inject" or plug in 4v directly to VDD_MAIN? I've seen another answer suggesting to "inject" 4v directly to VDD_MAIN to find the bad components, but i don't know much about it.[br]
[br]
2. With BATT_VCC is shorted, is it not a good idea to plug in 4v directly to VDD_MAIN, even if the VDD_MAIN itself is not shorted? Maybe it would cause a damage to the ic that is connected to both vdd_main and batt, like U3300?[br]
3. If i have a normal diode reading like the one that i found online, how much can it vary until it's considered too low or too high? With 0.355v for example, is 0.25v too low or it can be considered as normal, or acceptable?[br]
[br]
4. This last question might sound silly, the diode reading of 355 that i found online, is it 0.355v or 3.55v?
[br]
Additionally, maybe some general advice for a complete beginner like myself that is often hard to find on google?
[br]
Since this is my very first attempt to fix the board, i'm not expecting i'll be fixing this board and able to successfully boot it, but hopefully it does.
I apologize if this post is getting too long
Thanks!