m1330 no power, LED on AC supplier off - fixing report

Discussion in 'Dell XPS and Studio XPS' started by marcin.a, Apr 1, 2011.

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  1. marcin.a

    marcin.a Newbie

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    Hi Guys,

    It seems to be a common problem: Dell XPS M-1330 suddenly dies - no power, no light, and no response to any key. The blue LED on the AC power supplier goes off. To bring the AC supplier back to life it needs to be disconnected from the mains and reconnected back. Connecting it to the dead laptop immediately kills it again.
    Laptop is after warranty, Dell Norway asks for 5,000 NOK = approx. 900 UDS for the motherboard change. Quick googling reveals that many people have the same problem. But there seems to be only one person telling how to deal with it (except using Dell or other fixing companies) http://forum.notebookreview.com/del...rn-motherboard-gpu-failure-3.html#post6641913 I followed guideline form this post and brought my laptop back to life. I am VERY thankful to FixB4Replace - the author of the post above.
    You will need:
    1. read FixB4Replace post: http://forum.notebookreview.com/del...rn-motherboard-gpu-failure-3.html#post6641913
    2. follow M-1330 disassembly instructions e.g. from here AhWee.com - How To Disassemble Laptop (Dell XPS M1330) ? How To
    3. have M-1330 motherboard schematic e.g. from here (you need to register to see the files) Dell M1330 Model: PP25L - motherboard schematic
    4. have a regulated power supplier 0-16V, 0-2A
    5. have a multimeter
    6. have a soldering iron and solder
    First, take your laptop apart. I also advise to remove the processor and RAM, not to increase the damage in case things go bad.
    The repair idea is to connect the motherboard to the power and look for any part that heats up. Likely it will be the failed one, or one directly connected to the failed one. As very often the failure is caused by a shorted filter capacitor (they don't survive the constant power stress) it may be an easy fix. But you cannot use the original Dell AC supplier as it has an overcurrent protection (and for a good reason). You also cannot simply apply the power to the laptop power connector - there are two MOSFET power switches U41 and U42 preventing it (two small chips on the lower side of the motherboard close to the power connector). I connected the power directly to the pins 1,2,3 of U42 by soldering a thin wire directly to the printed circuit. The ground connection is easier - you can use almost anything. I attached a crocodile connector the DVD player housing. Now the power - it should be sufficient to heat up the failed part nicely, but not too much to cause any additional damage. I used 4V, 0.5A. After switching the power on the supplier over current protection switched on immediately. I was looking for the failure in the vicinity of the U42 chip and around that round cutoff in the motherboard. And it was not there. The hot capacitor was C10 located on the upper side of the motherboard, under that black foil, very close to the battery connector and the inter-board connector connecting motherboard and battery charger board. To see it I had to slightly peel that black foil off. BTW the capacitor was very hot. Amusingly, this capacitor was bearing obvious signs of manual soldering and a smear of yellow paint. This motherboard was a refurbished one from Dell... This laptop had exactly the same problem 1.5 year ago. I desoldered it and measured - its resistance was close to zero. Now the power supplier over current protection went off. I found a replacement capacitor in my box. It was of a much larger size (not SMD) which could not fit on the board. But there is some extra space behind the battery connector. I glued it there and connected to the printed circuit using two thin isolated wires. It is not an ideal solution. This capacitor really should be soldered directly on the board.
    Then I connected the power supplier to the laptop's power connector, dialed 16V, 1A. Success. Even some LEDs blinked. I put the laptop back together, reinstalled RAM and the CPU (remember to use new thermal conductive compound). Powered the laptop and voila.
    It took me approx. 3 hours. Could be no more than 1 hour if I knew what I was doing from the beginning, and had the schematic ;)
    I hope this much-too-long write-up can help somebody.

    Cheers
     
  2. mailord

    mailord Newbie

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    Hey,
    I am happy to find someone who has the same problem! I did what you listed to do, without supplying the board with power. I just checked C10 and also saw the yellow marking. Then I measured that this capacity was dead.
    But now I am trying to find a capacity on another old platine to replace C10. Do you remember the capacity of C10 (SC10U25V6KX-1GP)? I can't even decipher the part number.

    mailord
     
  3. marcin.a

    marcin.a Newbie

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    I don't remember it's capacitance right now. Should be somewhere around 10nF. It's capacitance is mentioned on the schema to which I posted a link. But first simply desolder this capacitor and see if the laptops revives. This capacitor is not absolutely necessary.
    BTW, you are looking for shorted capacitors. Capacitors with resistance close to or equal zero.
    Good Luck!
     
  4. mailord

    mailord Newbie

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    Yes, you were right. After desoldered C10 the problem was still there. So I soldered C10 again and I supplied the board with power of 2-4 watts (4V and 0.5-1A). Then I tried to find a hot spot, but it seems to be hard to locate it, because I found nothing hot.
    For a short time I gave 10 watts on the board (4 A) and C525 was getting really hot. I desoldered C525 and tried to run the board but the problem was still there. So I soldered C525 again.
    Do you have any ideas to find the short circuit element?
     
  5. Dolphin's Cry

    Dolphin's Cry Newbie

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    The same problem with my m1330. =(

    I supplied the board with power 1A 2V (I've connected the power directly to large resister R340 near U42). And there was nothing to be hot... the only hot thing was this resister.
    BTW: All capasitors like C519, C521, C523, C525, C10 and many others have resistance 5.2 Ohms...
    I have no idea what is a metter. Maybe someone gives an advice.
     
  6. mailord

    mailord Newbie

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    I measured a resistance of 1.7 ohms for the most resistances. Is this close or equal to zero? Maybe all resistances are in short circuit...
     
  7. jpfulton248

    jpfulton248 Newbie

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    Sorry for totally reviving a dead thread... and hopefully the mods don't mind that sort of thing, but I wanted to share my experience and ask a question...

    My M1330 bit the dust last night. I was determined to try anything possible for a reasonably cheap diy fix. I found the OP's post which is incredibly informative and helpful with excellent links... saves us from any hunting. I know absolutely nothing about circuitry or electricity or schematics etc... so I figured I'd just take a guess that the C10 was the problem. I grabbed a soldering iron and pliers and ripped the cap off the board. Then pieced everything back together and gave it a shot. Success.

    Obviously it is working without C10. There is no way I'll be able to replace the cap due to inexperience etc. What sort of damage might I be doing by running without C10? Is this shortening the life of the laptop or battery or adapter or something? Any comments would be greatly appreciated.
     
  8. marcin.a

    marcin.a Newbie

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    Hi jpfulton248
    I'm happy it worked for you. If your machine runs stable without this capacitor than it's fine. I don't expect (but can't be sure!) any further damage. It is not shortening life of the battery or adapter.
    Lack of such capacitor may cause ripples in one of the laptop power voltages. These ripples may cause instability in operation or even, but unlikely burn of an another element.
     
  9. jpfulton248

    jpfulton248 Newbie

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    Just to check back in for anybody in the future who might be interested. My M1330 is still working after removing the cap. I don't notice any instability (yet) and the battery life seems to be normal. Hopefully I can just keep going and run this thing into the ground.
     
  10. marcin.a

    marcin.a Newbie

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    Update:
    I got an another M1330 dead in the same way: No power, when connected to a charger kills the charger. Same thing - shortened filtering capacitor. Dell, shame on you. Shame.
    This time it was a large one located on the bottom side of the motherboard between processor socket and U41, U42 MOSFETS. I had to use 6V, 1A to get this large capacitor detectably hot. As these caps are soldered directly between power lines on the PCB there is no risk to fry the PCB (don't go higher than 18V). I simply ripped the cap off and that's it. I'm typing this email using the repaired machine.
     
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