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youpla
youpla
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Last Activity: 02-14-2026, 10:11 AM
Joined: 06-30-2020
Location: Orsay
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  • youpla
    replied to PowerColor rx 5700xt dual fan : current sense resistor
    in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals
    I just bought some 0-ohm resistors. Do you think there’s any risk in replacing the missing shunt resistor with a 0-ohm resistor ?
    I’m asking because the original shunt was a low-value resistor (likely 0.01–0.05 ohms), and I’m not sure if using a 0-ohm resistor could cause issues like:
    • Instability in the voltage regulation (since the current sense feedback would be lost),
    • Overcurrent risks (if the GPU’s power controller can’t measure current properly)
    • Potential damage to the GPU or other components.
    Has anyone tried this on a PowerColor RX 5700 XT (or similar GPU) ?
    Any advice...
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    • youpla
      replied to PowerColor rx 5700xt dual fan : current sense resistor
      in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals
      Nobody have a clue about value of this shunt resistor?...
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      • youpla
        started a topic PowerColor rx 5700xt dual fan : current sense resistor
        in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

        PowerColor rx 5700xt dual fan : current sense resistor

        Hi everyone,

        I’m repairing a PowerColor RX 5700 XT Dual Fan (not the Red Devil or Red Dragon model) with a burnt pin 5 on its 6-pin PCIe connector.
        The previous owner had it repaired by a shop. They soldered an enameled wire to reconnect pin 5 to the current sense resistor (shunt).
        The card wasn’t displaying anything after this fix.
        When I inspected their work, I found that the sense resistor had fallen off after reheating the solder joint (likely due to damaged pads from resistor).
        I tried to resolder it with a hot air station, but the resistor wouldn’t...
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        • youpla
          replied to Surface Pro 4 doesn't turn on
          in Troubleshooting Laptops, Tablets, and Mobile Devices
          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"....
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          • youpla
            replied to Surface Pro 4 doesn't turn on
            in Troubleshooting Laptops, Tablets, and Mobile Devices
            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...
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            • youpla
              replied to Surface Pro 4 doesn't turn on
              in Troubleshooting Laptops, Tablets, and Mobile Devices
              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 motherboard
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              • youpla
                replied to Surface Pro 4 doesn't turn on
                in Troubleshooting Laptops, Tablets, and Mobile Devices
                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 ?...
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                Last edited by youpla; 06-01-2022, 09:05 AM. Reason: English correction

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                • youpla
                  replied to Surface Pro 4 doesn't turn on
                  in Troubleshooting Laptops, Tablets, and Mobile Devices
                  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...
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                  • youpla
                    replied to Surface Pro 4 doesn't turn on
                    in Troubleshooting Laptops, Tablets, and Mobile Devices
                    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, Nicolas
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                    Last edited by youpla; 05-31-2022, 01:46 PM.

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                    • youpla
                      replied to Surface Pro 4 doesn't turn on
                      in Troubleshooting Laptops, Tablets, and Mobile Devices
                      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, Nicolas
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                      • youpla
                        replied to Surface Pro 4 doesn't turn on
                        in Troubleshooting Laptops, Tablets, and Mobile Devices
                        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...
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                        • youpla
                          replied to Surface Pro 4 doesn't turn on
                          in Troubleshooting Laptops, Tablets, and Mobile Devices
                          Re: Surface Pro 4 doesn't turn on

                          All VSB voltages must be present on standby ?
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                          • youpla
                            replied to Surface Pro 4 doesn't turn on
                            in Troubleshooting Laptops, Tablets, and Mobile Devices
                            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 clarify
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                            • youpla
                              replied to Surface Pro 4 doesn't turn on
                              in Troubleshooting Laptops, Tablets, and Mobile Devices
                              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...
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                              • youpla
                                replied to Surface Pro 4 doesn't turn on
                                in Troubleshooting Laptops, Tablets, and Mobile Devices
                                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, Nicolas
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                                • youpla
                                  started a topic Surface Pro 4 doesn't turn on
                                  in Troubleshooting Laptops, Tablets, and Mobile Devices

                                  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...
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                                  • youpla
                                    replied to Surface Pro 4 X911788-009 Schematics!
                                    in Schematic Requests ONLY!
                                    Re: Surface Pro 4 X911788-009 Schematics!

                                    Thanks a lot.
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