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Acer Aspire 5740g dead (no power - no lights)

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    #41
    Re: Acer Aspire 5740g dead (no power - no lights)

    No... PSU goes off just when put in to power jack.
    Actually i didn´t measure the coil... it was just from another user who got the same problem. honestly i only have a low budget multimeter... not sure if i can measure.. but ill try on the weekend :/
    Already tried the mobo without the cpu.. same problem. the thing is it seems to be a "common" problem... and some ebay user can fix it.. but they don´t tell how ;/
    dellxps did u hat the same problem like me.. or just no charging... ?
    i also heard/read the the power jack thing can build a short with the cooling metal from the motherboard...

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      #42
      Re: Acer Aspire 5740g dead (no power - no lights)

      i had dead laptop due to bad ec bios. for short u need a lab psu.

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        #43
        Re: Acer Aspire 5740g dead (no power - no lights)

        damn... i thought this would be easier

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          #44
          Re: Acer Aspire 5740g dead (no power - no lights)

          Any idea where to start to look for the shorted component... downloaded the shematic...

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            #45
            Re: Acer Aspire 5740g dead (no power - no lights)

            [SOLVED]
            It was a shorted capacitor.
            THX to all-

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              #46
              Re: Acer Aspire 5740g dead (no power - no lights)

              I have the same problem, no power, no 3.3v , 5v, the tps51123 have 5v enable, should try kbc dump ?

              Comment


                #47
                Re: Acer Aspire 5740g dead (no power - no lights)

                What do the following caps mean ? and which company ?

                Ex. SCD10U25V5KX
                SCD1U50V3KX
                SCD1U50V3KX
                SCD1U25V3KX
                SCD1U50V3KX

                Whats 5KX & 3KX ?

                Comment


                  #48
                  Re: Acer Aspire 5740g dead (no power - no lights)

                  I got valuable info about smd ceramic caps and resistors used in this Wistron M/B .
                  Check it out for yourselves.

                  RESISTOR->

                  Symbol name Value Tolerance (J: 5%, F: 1%, D: 0.5%, B: 0.1 %) Rating 0402=> 1/16W, 25V 0603 => 1/16W, 75V 0805 => 1/10W, 100V Size 2=>0402, 3=>0603, 5=>0805, 6=>1206, 0=>1210

                  The naming rule is value + R + size + tolerance For the value, it can be read by the number before R. (R means resistor) For the tolerance, it can be read from the last letter. For the rating, we don't show on the symbol name. For the size, R2=>0402, R3=>0603, R5=>0805,....

                  CAPACITOR->

                  Tolerance (M: +/-20, K: +/-10, Z: +80/-20)

                  Size 2=>0402, 3=>0603, 5=>0805, 6=>1206, 0=>1210

                  The naming rule is Capacitor type + value + rating + size + tolerance + material SCD1U10V2MX-1 SC=> SMT Ceremic, TC=> POS cap or SP cap D1U => 0.1uF 10V => the voltage rating is 10V 2=> 0402, 3=>0603, 5=>0805 M=>tolerance M, K, Z. X=> X7R/X5R, Y=> Y5V . -1 => symbol version, nonsense to EE characteristic.


                  Reference->

                  http://lanxicy.com/read/253b734a0dbaf75efbc09ff4.html
                  http://wiki.xtronics.com/index.php/Capacitor_Codes
                  http://wiki.xtronics.com/index.php/SMT_Case_Size_Codes
                  http://en.wikipedia.org/wiki/Electronic_color_code
                  http://en.wikipedia.org/wiki/Ceramic_capacitor
                  http://webstore.iec.ch/

                  Comment


                    #49
                    Re: Acer Aspire 5740g dead (no power - no lights)

                    Hello everybody,

                    Can anybody help me, I'm searching for KBC dump 7740G(Bios and EC Flash)?

                    Because I have the same problem with my 7740G(JV70-CP) and I don't know if I can use the KBC file from the 5740G for my 7740G

                    Many thanks for your help and sharing your information
                    Last edited by Rupke; 03-07-2015, 12:43 PM.

                    Comment


                      #50
                      Re: Acer Aspire 5740g dead (no power - no lights)

                      worked , thk for the bios file

                      Comment


                        #51
                        Re: Acer Aspire 5740g dead (no power - no lights)

                        Hi,
                        I have an Aspire 5740g dead too.
                        Following this discussion I checked the 3.3V and the 5V outputs of the TPS51223 on C732 e C716 (that are connected to VREG3 and VREG5 of TPS51123) and there are 3.3V and 5V. Anyway no power lights, no battery charge... what else should be checked? Could it be the BIOS problem even if the voltage is present?

                        Thanks.
                        Samuele.

                        Comment


                          #52
                          Re: Acer Aspire 5740g dead (no power - no lights)

                          If the voltages are present EC BIOS is ok, but main BIOS may be corrupted.
                          Originally posted by PeteS in CA
                          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                          A working TV? How boring!

                          Comment


                            #53
                            Re: Acer Aspire 5740g dead (no power - no lights)

                            Ok.. sorry for the question but what is EC BIOS?
                            Tomorrow I'll check the signals on U16 with an oscilloscope to see if communication with BIOS chip (that, at the end, is an SPI flash) is present, if there's no data communication should I suppose it is a problem with the BIOS chip on U16?

                            Comment


                              #54
                              Re: Acer Aspire 5740g dead (no power - no lights)

                              Some laptops only have one BIOS which has data for both the chipset and EC/KBC. EC/KBC stands for Embedded Controller/Keyboard Controller. All boards have this, it is a microcontroller that deals with all the basic stuff like handling the keyboard (hence its name), all the buttons and switches (including power button), all the LED lights, controlling the fan speed and so on.

                              Other boards have two separate SPI flash chips, a larger capacity one for the main BIOS which the chipset accesses and a smaller one for the EC/KBC. Physically they will be in the same footprint. Your board is like this. It would be better referred to as EC ROM, but for simplicity it is usually called EC BIOS. On your board U16 is EC BIOS. U56 is main BIOS.

                              On the board the EC is the large square TQFP package, the one with a lot of pins on all four sides.

                              To check the BIOS for activity using your oscilloscope, check pin 1 (Chip Select). It should always have a changing squarewave on it, which means it is constantly being accessed to do stuff. If the waveform moves for a few seconds and then stops, turning into steady DC, then the BIOS is bad and needs to be reflashed.
                              Last edited by Th3_uN1Qu3; 08-02-2015, 01:56 PM.
                              Originally posted by PeteS in CA
                              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                              A working TV? How boring!

                              Comment


                                #55
                                Re: Acer Aspire 5740g dead (no power - no lights)

                                Hi,
                                thanks for your explanation!

                                I've checked the CS pin (pin 1 according to MX25L1005 datasheet) on U16 and it is fixed on 3.3V (not changing) so I assume there's no communication with EC-BIOS on U16 (re-checked also 5V on C716 and 3.3V on C732 and they are at the correct voltage).

                                I also checked pin 1 on U56, but no communication detected. I cannot identify the model of the BIOS chip on U56 because the printings are blurred ('cause of the sticker).

                                Do you think I can assume the problem is due to faulty BIOS chips (both U16 and U56)?

                                Comment


                                  #56
                                  Re: Acer Aspire 5740g dead (no power - no lights)

                                  Originally posted by samuelef View Post
                                  Hi,
                                  thanks for your explanation!

                                  I've checked the CS pin (pin 1 according to MX25L1005 datasheet) on U16 and it is fixed on 3.3V (not changing) so I assume there's no communication with EC-BIOS on U16 (re-checked also 5V on C716 and 3.3V on C732 and they are at the correct voltage).

                                  I also checked pin 1 on U56, but no communication detected. I cannot identify the model of the BIOS chip on U56 because the printings are blurred ('cause of the sticker).

                                  Do you think I can assume the problem is due to faulty BIOS chips (both U16 and U56)?
                                  I've changed only the KBC BIOS on U16 and the laptop started working again!

                                  The situation was this:
                                  - No S5_ENABLE on TPS51223 (pin 18 TPS51223)
                                  - 3.3V and 5V OK from TPS51223 (C716, C732)
                                  - No SPI communication with U16 (pin 1 U16)

                                  Hope it helps someone with the same problem!

                                  Comment


                                    #57
                                    Re: Acer Aspire 5740g dead (no power - no lights)

                                    Hi, anyone help me acer asprie 5740g no power no light , vin volt 19v present , 5v/3.3v present but still no power no light.. please any idea

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                                      #58
                                      Re: Acer Aspire 5740g dead (no power - no lights)

                                      Originally posted by samuelef View Post
                                      I've changed only the KBC BIOS on U16 and the laptop started working again!

                                      The situation was this:
                                      - No S5_ENABLE on TPS51223 (pin 18 TPS51223)
                                      - 3.3V and 5V OK from TPS51223 (C716, C732)
                                      - No SPI communication with U16 (pin 1 U16)

                                      Hope it helps someone with the same problem!
                                      I had the same and I got it to work, I had problems with the programmer saying it was a 512kb chip and not a 1mb, I read the original and I got a 64kb file, when I tried to load the 128kb file it kept failing but after several attemps it worked, even though it still read as 64kb the laptop boots

                                      Comment


                                        #59
                                        Re: Acer Aspire 5740g dead (no power - no lights)

                                        I had the same problem... 64Kb and 128Kb to stuff into it, chip was 25L1005...that is a 128Kb device.

                                        My CH431 programmer reported device smaller than file...didnt auto detect the chip correctly, manually set the device to MX25L1005 and order was restored. 5740 up and running

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                                          #60
                                          Re: Acer Aspire 5740g dead (no power - no lights)

                                          Originally posted by nero80 View Post
                                          Acer Aspire 5740G KBC BIOS Dump
                                          Thank's the bios is work perfectly

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