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Fifth generation of iPhone. Repair of this device is straightforward, and requires screwdrivers, prying tools, and patience. GSM/CDMA / 16, 32, or 64 GB / Black or White.

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How to test if logic board is broken

I've got this iPhone 4S which shows a lot of issues:

  • Wifi is grayed out
  • Bluetooth is not working
  • No cellular signal (but here I saw the antenna connector to the logic board is missing, so this can be replaced)
  • Vibrator is not working
  • Mic is not working
  • Speaker (bottom) is not working
  • Camera LED is not working
  • Battery is not working (iOS always reports a full charge, even if no battery is installed)
  • Proximity sensor does not seem to respond
  • Audio jack (also no signal from Apple earpods remote)
  • GPS data (and compass) not working

These things are working:

  • Front camera
  • Back camera (but not the LED)
  • LCD works perfectly
  • Touch works
  • All buttons work (volume, mute, lock, home)
  • Home button
  • Dock connector (to power up)

Not tested (or not able to test):

  • Charging
  • Earpiece

I've also noticed that this iPhone is jailbroken (there is a Cydia app).

I've received this iPhone in exchange for my own 4S which has drowned. This repair center has moved and is unable to be contacted. So after a few months I gave up and decided to try to get this other 4S working. I was planning to buy a bunch of parts but I'm having a feelding something is wrong with the logic board. Is there any way to test it or to test any of the parts on them selves?

I have already tested the battery which does not seem to give any voltage between the outer connectors.

I don't want to buy all the broken parts if it turns out to be the logic board.

Answered! View the answer I have this problem too

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2 Answers

Chosen Solution

lmao so much is wrong but yours was drowned so you are better off lol anyway, i would recommend replacing the parts first and then test the phone to see how it runs... luckily it turns on so it cant be that big of a logic board issue...

in this case the closest it comes to becoming a logic board issue is if you replace a certain part, it powers on and still doesnt work, then its connector located on the motherboard is defective and would require extremely professional soldering which can be hard if you dont know what you're doing...

you will definitely need to replace the parts requiring signal like the antennas especially before you can test anything because those are the parts that heavily determine logic board issues which i doubt you have here, but things like the gps, wifi, cellular signal, things of those sorts...

again luckily it turns on, so the biggest and most common logic board issue is ruled out...

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I've ordered a new set of screws (since most of them were missing) and a new cellular antenna with the loundspeaker.

I'm curious how this will turn out. :)


update as you perform the tests im curious as well, a "salvaged" iphone, i hope it does make it out the infirmary lol


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Hi there ..

my iphone 5 i dnt know what is the problem

i tested the LCD and in works so well

and i play need for speed nolimits with no wrong..

BUT sometimes the touchscreen doesnt respond at all>???

and after a while start working with no problems

how to test the board and the touchscreen and the processor ???!!!

i mean how to know what is the problem ???

thank U AL :)

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Jeroen will be eternally grateful.
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