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Hey iFixit Community,
I recently bought a used iPhone 8 A1905 from eBay. Got it pretty cheap so i thought i’d try to get it running. So the seller told me that after it fell (back is completely broken) it was dead. It doesn’t vibrate / gets recognized by iTunes. The Display didn’t take any damage and everything else is Original as it was never opened. Anyone have an idea what this could be?
Thanks
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@actualnoob Yup, some try and error needs to be done, otherwise we’re just guessing without any clue. Take apart screen and start disconnecting parts from the logic board, then plug back one by one starting from lightning dock. Hope you have at least a USB Ammeter to see if the board draws any current or it’s shorted for good..if you don’t have it you’ll need to buy one to start with. In case you’re a lucky guy, you’ll see some life signs with just dock and battery..plug into a PC to see if the iPhone gets recognized. In case it doesn’t you’ll have to try with a known good dock and battery. In case you still have no life signs, then you probably have a board issue.
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If you did all the above and determined it is a board problem. Post the diode readings of the following lines. You will find these on the dock connector.
• 90_HYDRA_DP1_CONN_N
• 90_HYDRA_DP1_CONN_P
• 90_HYDRA_DP2_CONN_N
• 90_HYDRA_DP2_CONN_P
• PP3V0_LAT_CONN
• HYDRA_CON_DETECT_CONN_L
We will also need the following voltages for these lines.
• PP_VDD Main
• PP1v8 – always
• PP3v3 USB
• PP 3v0 Nand
• PP0v9 - Nand
• PP1v8 – Io
• PP1v8 – SMPS4_E
Report back with these readings and we will go from there.
@imicrosoldering Nice addition, now we got a full troubleshooting guide, beginner and advanced :)
Ok so at the moment I ordered some Parts (and a usb voltage / ampage meter). I didn’t want to be sitting around doing nothing so I took the entire phone apart. Now only having the Battery and Dock connector connected i can hear a slight ticking noise from the logic board / logic board area. Now that pretty much assures me it’s a board issue right?
@actualnoob Yes, I'd say so.
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Step by step here
Connect the phone to an expernal power supply and set the voltage to 3.9V. Then turn on the phone and keep a close eye on the current it takes,. It should not go above 1.2A If it does shut the phone down immediatly.
Before you u turn the phone on with the PSU connected the currrent should be zero
Take your results turn your phone off and post them here
Depending on your results we will knonw the next step to take
This is a step by step process to find the faul
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Just hold on a while, I'll dive into electromancy and some crystal reading and I'll be back to you ;)
arbaman さんによる
alright then it’ll be trial and error ;)
Mark Schallenberg さんによる
You’ll have to open it up and take a look at the components for damage. Use the tear down videos here or on YouTube to identify components and check connections.
drmdolfan さんによる