Released on September 19, 2014, this 4.7" screen iPhone is the smaller version of the iPhone 6 Plus.

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iPhone 6 no image and cpu hot

Hello,

I have a trouble with a silver iPhone 6, that it has no image, even I changed the lcd, but the problem always exists, and by analyzing circuits to retrieve short circuits

I noticed that the cpu is getting so hot, when plugging battery to the logicboard , so I removed the EMI shield and I noticed that coil inductors are little bit damaged, so I don't know what should I do .

Thank you so much.

Here's some photos :

https://ibb.co/k9VJRa

https://ibb.co/e1zjzv

https://ibb.co/d6Gsma

https://ibb.co/hj2bCF

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Deck the Halls
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The coils look like they were damaged when you removed the shield. I'm a little concerned about the second and third one from the top. On the third and fourth pictures, I notice some solder balls between the CPU and the components. This could be related to the overheating but more likely you applied too much heat when removing the shield. What did you use to desolder the shield?

As far as your original problem (no screen image), it sounds like it may be a backlight circuit issue. You need to check the ferrite bead that filters (Fl2024) the anode line (PP_LCM_BL_ANODE) for the backlight. Then work your way upstream towards the diode (D1501) and filter (L1503). Hopefully you have the schematics, otherwise, search for it on Google to help you locate the components.

Get back to me by commenting on my answer and let me know what you find on the backlight circuit and please confirm if what I see are solder balls (that would be bad news).

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Hello,

Thank you for replying , I did check the FL2024 filter, D1501 diode and L1503 filter , but there's no short , there're all working fine

Any suggestions please

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Have you checked the cathode lines?

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Yes , I had tested FL2024, FL2026 and the multimeter give 033 in diode mode.

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Well actually i have a working iCloud logicboard that I would like to replace it containts but i found a different structure in cpu and coil inductors , could you please have a explanation about it .

Pics :

http://ibb.co/hkajZv

http://ibb.co/fiN3SF

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Assuming the two logic boards have the same part # (820-3486-A), then it's just the packaging of the inductors that are different.

As for the measurements, why are you testing inductors in diode mode and what are you measuring in relation too? If you want to test an inductor, measure across both sides in resistance or continuity mode and look for a near-zero resistance.

Also, you didn't mention FL2025; did you test it too?

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No image in an iPhone 6 solution, step by step guide:

How to fix no image / black display for iPhone 6

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@brahimeb, I believe you will have to check that voltage with the screen connected to get the 6v LCM_Boost from Chestnut

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as well as L1519 boosting VCC_Main from 4.2 on one side to 6v on the other

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Check FL2027 PP1v8 for 1.8, FL2061 PN5V7 for -5.7, FL2037 PP5V7 for 5.7, FL2035 (LCM_CHESTNUT_PWR_EN) and FL2036 (AP_TO LCM_RESET) for 1.8 with screen connected as well as FL2050 (PMU_TO_PHOTON_ALIVE) for 1.7 - 1.8

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Thank you Michael for replying , here's the results :

L1519 : 4.07V and 3.07V on the other side

FL2027 : 1.78V

FL2061 : 0V

FL2037 : 0V

FL2035 and FL2036 : 1.78V

FL2050 : 0V

I think it's LCM Supplies issue , what do you think about ?

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@brahimeb, Do you have your screen attached when checking? There are some voltages that will not appear with it disconnected. If you do have it connected, you are missing about 1.75 from PMU to photon Alive, -5.7 from PN5V7_Sage and 5.7 from PP5V7_LCM...and with not getting a boost to almost 6v from L1519, I would think that U1501 Chestnut would be responsible for those issues or circuits connected to it You say you are also getting 3.2 from C1529 and 0 from C1502...These are PP6V0_LCM_BOOST, also connected to Chestnut...are they Okay? Shorted? Maybe someone with a bit more experience should answer but my first instinct is to replace Chestnut and re evaluate. You said no image and CPU getting hot... It could be Chestnut cause it can get hot enough to burn ya and it's right up next to CPU.

Check out this Video by Mark Shaffer https://youtu.be/JCG1Cc5u53s

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Thank you Michael , I'm waiting for the U1501 Chestnut to ship from China, I'll tested as soon as I get it

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Hello back , I've replaced the U1501 and nothing happens , but the strange thing is that the phone is working even without the U1501 ic (Recognized in iTunes)

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That is the fault of u2 ic.

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I don't think so , the phone is charging normally and it's recognized in iTunes

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What are the issues with the U2 IC? What is happening to the phone?

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Ibrahim will be eternally grateful.
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