Replace mainboard fuse Compaq 6715s

Discussion in 'PC Hardware' started by Padpadak, Jul 7, 2012.

  1. Padpadak

    Padpadak MDL Member

    Feb 11, 2010
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    Hy all,

    Problem : Very dark laptop screen.

    Already tried :

    New screen
    New inverter
    Looked at the Lid button on the mainboard
    Checked the cabel

    Solution ?

    I think that the fuse on the mainboard( sp nr 443897-001)Is broken.because all the inverters I tried get no power from the mainboard, even not with new cables.
    I want to replace this only I don,t know with fuse It is, He must be somewere near the cable connection on the main board

    Does somebody knows what the nr of the fuse Is on the mainboard ?

    Thanks in advance,

    Pascal
     
  2. QuantumBug

    QuantumBug MDL Developer

    Mar 7, 2012
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    Attached Files:

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  3. QuantumBug

    QuantumBug MDL Developer

    Mar 7, 2012
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    Any chance you could send me a picture of your Motherboard? With good coverage/view of the internal screen connector, and rear side.

     
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  4. Padpadak

    Padpadak MDL Member

    Feb 11, 2010
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  5. QuantumBug

    QuantumBug MDL Developer

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    #6 QuantumBug, Jul 7, 2012
    Last edited: Jul 7, 2012
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  6. Padpadak

    Padpadak MDL Member

    Feb 11, 2010
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    Step by step come a littlebit closer I think.

    External monitor works good

    I replaced the complete screen + cable + inverter from another 6715s.
    Instead of a very dark screen(only seen with a flashlite),I have now a screen what Is as bright, when you turn your screen energy to the lowest brightness(for example when you work on battery)

    I tried the FN key + the brightness keys, but the bar goes from left to right and back, but nothing happends with the brightness of the screen.
    The bar does react with the key ,only the screen does not react.
    Also the bios screen when you start up is darker than normal.

    Tried to reinstal Windows 7, but still a darker screen

    ps: the screen what I replaced was bright on the other laptop.

    Thanks in advance for the thinking ;)
     
  7. QuantumBug

    QuantumBug MDL Developer

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    Any more luck with the issue?
     
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  8. txarmysgt

    txarmysgt MDL Novice

    Jan 18, 2010
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    Look closely at both screens (new and old) Both Inverters, and both LVDS Cables. you'll be surprised. LCD Screens in laptops can be an absolute nightmare trying to swap from one to another. It sounds like there is a mis-match somewhere in your path from the Mainboard to the screen, or perhaps the bios does not have brightness tables for the particular screen you have swapped in ( is the bios version the same on both laptops?) my bet is you will find completely different screen part numbers, different inverters, and different LVDS Cables even from the same model laptop with the same resolution etc. If you tried mix-matching along the way you could have damaged the new inverter. this is very intentional in the industry. in fact a number of prominent LCD screen manufacturers have come under fire by the US Government for violating antitrust laws.
     
  9. Padpadak

    Padpadak MDL Member

    Feb 11, 2010
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    Have stil the same screen, till now no luck

     
  10. Padpadak

    Padpadak MDL Member

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    #11 Padpadak, Jul 9, 2012
    Last edited: Jul 9, 2012
    (OP)
    The bios is exactly the same on both laptops.
    Is is not possible that something on the mainbord is broken a diode or something ?
    I mean that the problem is not the screen but that the issue is that the mainboard don't give the power to the screen to become bright ?
    Then I can try many screens, but maby the problem is one the mainboard ?

    The screen also don't change when I use battery or wallpower

     
  11. Padpadak

    Padpadak MDL Member

    Feb 11, 2010
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    UPDATE:

    I just see that the battery don't load when the laptop is on Wallpower.
    The battery is good, also the adapter, because the battery does load In the other laptop with the same adapter and the same battery.
    Has this maybe something to do with the darker screen ?

    Best Regards
     
  12. QuantumBug

    QuantumBug MDL Developer

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    Must be a motherboard issue then, do you have a heat gun?
     
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  13. QuantumBug

    QuantumBug MDL Developer

    Mar 7, 2012
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    Also, the LCD video cable, where it connects to the motherboard; check the connectors inside are good and check the solder underneath the connector is making contact with the motherboard. Something on your motherboard isn't right.

    @Txarmysgt

    If it's the same Laptop the other parts will work regardless of revision. Even if the BIOS doesn't match they can't lock out different revisions of hardware.

    @padpadak

    Have you reflashed your BIOS at all?
     
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  14. Padpadak

    Padpadak MDL Member

    Feb 11, 2010
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    @ Dave

    I have a heat gun.

    Reflashed the Bios
    Checked the pins In the connector, no corrosion of strange things.
    The solder by the connector seems also oke for me.

    Can it be a combination that the motherboard don't give enough power to the screen on some way ?because of the don't recharge issue with the battery ?

    Is it not better to find an other motherboard ?
    I am not able to find the correct fuse, diode or other little parts on the motherboard, to measure if they are broken.
    Checked also with strong glasses(don't know the name in Engilsh :eek:)If I could find burned things on the motherboard.

    Best regards,
     
  15. QuantumBug

    QuantumBug MDL Developer

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    If you're going to replace the mainboard anyway, I'd suggest heat treating the board to see what happends.

    Remove all plastic etc, from the motherboard, slowly heat the board for a few minutes, then cover the whole board with the heatgun with a 15-20cm gap, don't let it get too close and do this for about 5 minutes, never hold the heatgun in the same place for too long, then turn the heatgun down and cool the board from +/- 20cm away for 5 minutes. If you don't do the last step the board may crack, always cool the board with the heatgun rather then just stop.
     
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  16. txarmysgt

    txarmysgt MDL Novice

    Jan 18, 2010
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    I would make certain that you swap all the screen components together as a set. OEM's source screens from numerous sources and it is not at all uncommon for two otherwise identical laptops to have screens from different vendors. I once won an Ebay auction for 6 Dell D610 screen assemblies and each one of them had different screens and lvds cables and there were at least three different inverters among them. If you experiment you could easily blow the fuse on the inverter (I know this first hand) the fuse is typically located very near to the input jack on the inverter. You rarely see glaringly obvious damage so I would check for continuity across the fuse on each inverter with a meter to be sure. sometimes it is difficult to make solid contact with the solder pads on surface mounted components with your test leads. if you have a soldering iron consider flowing a tiny bit of solder on the joints and then test. It may be flux residue coating the solder joints from the factory but I have found you have to press the leads harder than I am comfortable with at times to make solid contact. reflowing the joints will solve that. Hope it helps. OH - once you verify the inverter's I would try checking the bulbs on each screen. hook your screen up as you typically would and power up. if no backlight, power down, then unplug the bulb from the inverter leaving the rest in place, and plug in the bulb from the other screen. (you will have to jockey the screen your testing around a bit and it may seem awkward but your goal is to determine if the bulb lights up so you won't have it that way long) then power up again. if the backlight illuminates then you know the bulb on the other screen is no good.
     
  17. abbs2002

    abbs2002 MDL Junior Member

    Jun 3, 2012
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    #18 abbs2002, Jul 12, 2012
    Last edited: Jul 12, 2012
    If you can remove the screen cable off the motherboard and attached an external monitor that would tell you for sure if the laptop screen is faulty or the motherboard. Also check the ram and past on the cpu if it has gone dry.
    also check the switch that turn off monitor when the lid is down that can get stuck sometimes and the screen wont light up.
     
  18. QuantumBug

    QuantumBug MDL Developer

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    #19 QuantumBug, Jul 12, 2012
    Last edited: Jul 12, 2012
    Most of this has already been discussed earlier in the post :)

    BUT, Padpadak, I think abbs is right about the switch.

    Have you had a fiddle with it?
     
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  19. Padpadak

    Padpadak MDL Member

    Feb 11, 2010
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    Thank you all to give me some tips and info.

    Tried all what you adviced, heatgun, cpu ,switch... ect.

    This laptop was my main laptop, no a project to do in your free time.
    Ofcourse It Is really cool to solve the problem, but I don't have the time to be busy with the laptop for weeks, I also need a laptop for work.
    I am going to put everythig together, and hoped the laptop will work.
    Even with the screen what Is not really bright,I can work on It.

    I think the laptop Is not worth anymore to put time and money In it, and even not be sure that I can fix It.

    I can better look for an other laptop, sell this one for parts and put the money In another one.

    So for me this thread can be closed.

    Again thank you all a lot, to help me with all your knowledge :worthy::worthy::worthy:

    Best Regards