Re: Surface Pro 4 doesn't turn on
I managed to retrieve my first situation by replacing another time the IT8520G. As before I have an fluctuating voltage (between 7.5 volts and 8.69 volts) on the big inductor mark with an red rectangle on the first picture when power adapter is plug in. Someone can tell me if this fluctuating voltage is normal ?
I noticed that this fluctuating voltage is also present on mofset near power adpater connector (picture 2). If I am not wrong, according boardview, gate pin on the left mofset is connected to the third pin of an 6 pin labelled "DP"....
youpla
Member
Last Activity: 05-12-2023, 03:49 AM
Joined: 06-30-2020
Location: Orsay
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Re: Surface Pro 4 doesn't turn on
Something change on my surface pro 4 motherboard.
Last evening I decided to let charge battery during all night long to carry on my tests using battery.
This morning I notice battery is flat whereas voltage was about 7.5 volts before I put battery in charge.
Now I have only 2 volts on big coil and 0 volts on output mofset near charging port.
I have 2.45 volts on coil from 3.3 volts rail and 0.62 volts on coli from 5.5 volts rail (near USB port).
I can't figure what happens....
Could you give me some help or give...Leave a comment:
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Re: Surface Pro 4 doesn't turn on
I puted battery back in case of VCCDSW_EN will appear unfortunatly it isn't the case.
Maybe I resoldered the chip it8528vg wrong.
However I find the voltage 3V_EC. Is this a reliable indication that I have soldered the chip correctly?
I'm afraid it's game over for this motherboardLeave a comment:
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Re: Surface Pro 4 doesn't turn on
I watched somes videos and it appears that when main board is just connected to charger (without battery) which is my case, I have to find 3.3 volts and 5 volts on coil on the left of PCB near USB port (see attachment).
Someone can confirm ?
If true, TPS51385A could be defective ? It's an driver for 3.3 volts and 5 volts FET if my understanding is good ?...Leave a comment:
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Re: Surface Pro 4 doesn't turn on
Hi reformatt,
Thanks a lot for your help.
Unfortunately I don't own a flash eeprom writer in order to flash eeprom of it8528vg.
Just an question for you. What do you think about voltage of 1.54 v on coil near USB port. According board view I was expected to find 3.3 volts. And what about 3 ohms to ground found on coil from cpu power rail. You could find all measurements I talking about on my first attachment.
And finally my last question for today. What means VSB after a voltage name.
Best regards, Ni...Leave a comment:
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Re: Surface Pro 4 doesn't turn on
If I understand, at step 5 I have to find voltage for VCCDSW_EN. With boardview I found an point to meseaure this voltage which is 0 volts on my board.
According you, what value I have to find ?
An stupid question but what is meaning of EC after voltage value ? Same question for VSB ?
Best regards, NicolasLast edited by youpla; 05-31-2022, 01:46 PM.Leave a comment:
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Re: Surface Pro 4 doesn't turn on
Hi reformatt,
I just check +3PV3_EC and I found 3.27 volts which is good and for EC_RST# (called I guess EC_RST_ in boardview) I found 3.14 volts which is high value I guess.
I don't have a scope to test data lines of EEPROM of IT8528G.
I only own an multimeter.
I will try to follow step of power sequence diagramm.
Thanks a lot for your help.
Best regards, NicolasLeave a comment:
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Re: Surface Pro 4 doesn't turn on
I also try to find some clues by using page 5 of schematics. This page deals with power sequence. I focus on first steps.
According this page, voltages of always_on and 3P3VA_EN go to an step-down converter which produce differents voltages. I could see it on first attachment.
With help of ifixit teardown, I think that I localised an step down converter. Values seem be good except 3P3VA_FB and 3P3VA_SLEEP. You could see values on second attachment.
Am I not be able to localise step down converter for 1.8 volts...Leave a comment:
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Re: Surface Pro 4 doesn't turn on
All VSB voltages must be present on standby ?Leave a comment:
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Re: Surface Pro 4 doesn't turn on
No 1.8 Volts VSB either.
I test standby voltages with charger only, no battery connected. I don't no if it's an important observation but I want to clarifyLeave a comment:
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Re: Surface Pro 4 doesn't turn on
Hello,
As mentioned I try to use schematics and board view to manage to understand what happens with my surface pro 4 motherboard.
According schematic page 8, I have to find 3.3 vsb and 5 vsb which to be presents on standby.
With boardview, I manage to find points on motherboard to mesaure this 2 voltages.
For 3.3 volts VSB I found 1.5 volts and 0 volts for 5 volts VSB.
I think with my limited knowledge to solve this problem first.
What do you think . It's a good start ?
Have you some clue to find...Leave a comment:
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Re: Surface Pro 4 doesn't turn on
Hello,
Thanks for your replies and your help
Indeed I already founded schematics and boardview for my Surface Pro 4 on this forum.
I will pay attention on pg 5 of the schematic to see if I could find some usefull informations.
As I said, am I an enthousiast not a tech with a lot of knowledge, I am not sure to understand a lot of thinks.
Best regards, NicolasLeave a comment:
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Surface Pro 4 doesn't turn on
Hi,
My name is Nicolas, I live in a little town near Paris, France.
I like to try to fix electronic stuff principally game console but I try to change device type.
I bought few days ago an Surface Pro 4 (core i7 cpu, 8Go of memory). Seller told me that I had a lot of difficulties to wake tablet after puting it in sleep mode and one day it was impossible to switch on his tablet.
I managed to remove screen (but I broke it
) and check what if found as common faillure on net :
* charging diode
* bad fuse
* bad it8528g
All my mesurments... -
Re: Surface Pro 4 X911788-009 Schematics!
Thanks a lot.Leave a comment:
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