What are basic diagnostic tests on a Windows laptop that won'tboot?

Discussion in 'HP' started by Calia, May 26, 2014.

  1. Calia

    Calia Guest

    Those of you with experience troubleshooting a dead
    laptop, can you provide advice?

    I have a Windows 7 HP G72 laptop which suddenly stopped working.
    Do you have an idea how to do basic troubleshooting?

    What happens when I try to reboot is that nothing shows
    up on the 17-inch screen whatsoever.

    The only indicators are the fan and a half dozen LEDs.

    The fan is most notable.
    When I press the power switch, the fan goes on for what
    I timed at 40 seconds. Then the fan goes off.

    The white LED to the immediate left of the topside power
    switch glows white when the computer is turned on.

    The orange and white LED next to the power input on the
    right side of the pc also glows either orange or white.

    The white capslock key LED blinks white synchronously with
    the NumLock key. The F12/WiFi function key glows orange.

    The tiny LED on the DVD tray button does not light, nor
    will the DVD tray open unless I insert a paperclip.

    I found this "maintenance guide" but it doesn't seem to
    list these conditions:

    Those of you with experience troubleshooting a dead
    laptop, can you provide advice?

    Mainly I just want to know if I can pinpoint the failure
    and then I can see whether it's worth trying to fix.
    Calia, May 26, 2014
    1. Advertisements

  2. Calia

    Calia Guest

    Actually, now that I have said that, my second timer run
    shows the fan continually running.

    So, to clarify, the only indications of anything working
    are the fan runs continually, and a few LEDs light, as
    stated prior.

    Curiously, the hard disk drive LED light on the left
    side does not seem to be lighting up at any point.
    Calia, May 26, 2014
    1. Advertisements

  3. Calia

    pjp Guest

    Ugh!!! I take it it's not under warranty? Even with the hard disk toast
    I'd expect to see the display come alive. Has the power brick given up?
    That's about only test I can suggest, e.g. is it providing 12 volts or
    whatever. Try to find another rated more or less same and try it

    Other than that if it's not under warranty and you can't find some
    "specialty shop" deals with laptops almost exclusively you likely have
    some parts is about it, e.g. hard disk can likely be used in some
    enclosure as an external drive etc. Fact of the matter is cost of time
    to repair likely comes close to cost of replacing. Sorry for your loss.
    pjp, May 26, 2014
  4. Calia

    Geoff Guest

    Bad RAM will stop boot too.
    Geoff, May 26, 2014
  5. Jumping to a premature conclusion, I would guess(tm), that you have
    the same problem as all these people:
    Unplug the charger. Remove the battery. Go away for about 10
    minutes. Put the battery back in and do not plug in the charger. If
    the battery is totally dead (i.e. shorted from sitting at zero charge
    for too long), it might not turn on. If you suspect that you have a
    shorted battery, and can't find a suitable replacement, remove the
    battery, insert the charger, and see if it will power on with just the
    That might be an HP G72-227WM. Is that correct? (Complete and
    accurate model numbers are always helpful).
    Ummm... It should go at full blast for about 2 seconds, and then spin
    slowly. 40 seconds implies that some timer on the MB is not working
    OK, the power switch is working. Is there anything on the screen? If
    not, take a flashlight and shine it around the upper left of the
    screen, where the BIOS boot messages appear, or in the center of the
    screen, where the Windoze logo normally appears. If you see
    something, then the backlighting is blown. The G72-227WM has an LED
    backlight, so there's no inverter to replace. The problem will be to
    determine if the lack of backlighting is caused by a problem on the
    motherboard, LCD panel, cable, or connector.
    White means it has power. Orange means it's charging. No light means
    that it's charged. Flashing means your battery is so low as to not be
    able to power the laptop.
    HP Blinkenlighten codes:
    That's meant for users, not techs.
    Yes, I can. Try asking in the HP support forums:
    Hint: You'll need to provide a better description of the flashing
    lights and boot errors.
    In my never humble opinion, the last few years of HP and Compaq laptop
    are not worth fixing. I hesitate to fix them because they don't stay
    fixed. I often see them back in a few months, usually with a
    different problem. Details and horror stories on request.
    Jeff Liebermann, May 26, 2014
  6. Calia

    Calia Guest

    The warranty died long ago.
    Nothing shows up on the display.
    Here is a picture with the power on and the fan running:
    I don't know. I will try to get test leads into those tiny holes.
    It appears to be charging the battery and the battery appears to
    work, so, I've tested all three cases:
    a) With just the battery
    b) With the AC power and the battery in
    c) With the AC power and the battery out

    Calia, May 26, 2014
  7. Calia

    Calia Guest

    It's a little tricky removing those memory cards.
    They seem to have a fancy "clasp" on the sides, but, I will
    keep trying until I get them out:
    I am taking your advice and have removed the hard
    drive, and will re-insert soon:
    Calia, May 26, 2014
  8. Calia

    Calia Guest

    I removed the two memory cards, and swapped them, and put
    them back, and powered up, but to no avail.

    Calia, May 26, 2014
  9. Calia

    Calia Guest

    My mistake. I apologize.

    Inside the battery bay is the model & product number:
    Model G72 B54NR
    Product XR826UA#ABA
    I had to look up Ball Grid Array, which, when I found what it
    was, looked far beyond my capabilities.
    Tried that. Nothing that I can see.
    Thanks Jeff.
    I had no idea those keys were blinking a code!
    I followed the procedure at the suggested location:

    Basically, I removed the power & battery & discharged the computer
    by holding the power button down for 30 seconds and then hooked
    just the AC power but not the battery.

    1. The AC adaptor light at the right side goes white.
    2. The capslock & numlock light stays white (i.e., no blinking).
    3. The F12 is a steady orange.
    4. I press the POWER switch.
    5. I hear the fan but not the HDD nor do I hear any beeping.
    6. The AC adaptor light on the side of the PC stays white.
    7. The capslock & numlock keys blink once for 1 1/2 seconds,
    and then they go off for 4 1/2 seconds.
    8. I can discern no other pattern than that 1.5:4.5 seconds!

    The really bad news is that a single blink in the table reads:
    "CPU not functional"

    Is that as horrible as it sounds?
    Calia, May 26, 2014
  10. Calia

    Paul Guest

    You test the memory SODIMMs, one at a time.

    Do not insert both.

    Try only one of them.

    If still a problem, remove that one and try the other.
    It is unlikely for them to both fail at the
    same time (although that has happened to me).

    Paul, May 26, 2014
  11. Calia

    Paul Guest

    Black screen with blinking error code LEDs are described here.

    Try to match the table info, to your machine. Applies to
    UEFI BIOS machines.


    And this is my proof that a G72 may be using a UEFI BIOS.


    Paul, May 26, 2014
  12. Calia

    Calia Guest

    I will likely try overheating the motherboard, to solve
    this problem, as per this video on the HP G72:
    Calia, May 26, 2014
  13. Calia

    Calia Guest

    Calia, May 26, 2014
  14. Calia

    Paul Guest

    Not necessarily true. It could be the VCore regulator
    near the CPU socket which is not functioning. It could
    be a loss of power feeding into the VCore regulator (like
    a problem with the circuit distributing power from battery
    to elsewhere inside the computer).

    CPU/Processor chips are very reliable.

    On laptops with a separate GPU chip, some of those have
    problems with cracked solder balls. But for the
    CPU socket, it could be using a thruhole socket
    with land grid array springs to make contact with
    the CPU. And that doesn't have nearly the same issues
    as a fine pitch BGA might.

    Also, when you see LEDs blink, they may not be
    blinking due to the "test procedure". They could
    instead blink because of the way a power failure
    is happening inside the unit. For the entries in the
    table with multiple blinks, seeing the LED blink
    multiple times would be a reasonably reliable
    indication of a problem. But when you see one blink,
    is that a "CPU test failure", or is it "the power
    regulator just turned off". We don't know. Some
    test results will not be that accurate and specific.
    And it would be a mistake to jump to a conclusion just

    I would retest with battery pack IN versus
    battery pack OUT, and see if the timing of the
    blink changes at all. If if was a true CPU
    test failure, the timing should not change at all.
    If the blink duration seems quite different,
    between those two test cases, it could be an
    internal power distribution issue.

    Paul, May 26, 2014
  15. Calia

    Calia Guest

    If the overheating of the motherboard doesn't work, is it
    feasible to remove the motherboard and somehow, "reflow"
    the solder joints?

    For example, in this video, a guy removes & replaces
    a chip with some sort of brass torch tool:

    Is the IC replacement as easy as that video makes it seem?
    (Seems to me the chances of getting all the pins lined
    up and nothing shorted elsewhere has got to be near zero.)
    Calia, May 26, 2014
  16. Calia

    Paul Guest

    You use a hot air rework station for BGA replacement.


    On good quality PCB material, a BGA site can be repaired
    up to three times, without damage to the PCB.
    Computer motherboards are not high quality,
    so your mileage may vary.

    The hot air rework, applies heat from the top
    of the PCB. It also applies heat from the bottom.
    This is to reduce stress on the PCB. On the top side,
    the area to be heated, is controlled by fitting
    a metal "hood" to the nozzle. There are different
    sized hoods for different sized chips. (We had
    at least 20 different ones for our machine at work.)

    On the top side, a "vacuum wand" can be used to lift
    the molten-hot chip off its PCB site. That's when it is
    hot enough. The small knob on top of the tool in
    the picture above, could be related to chip release.

    When you put down a new chip, the soldering process
    is "self aligning". When the new chip is heated, to make
    the solder balls melt, the surface tension of the solder
    helps "attract" each contact, to its mate on the PCB.
    So even if the chip is rotated 1 degree from ideal
    position, it will "snap" into position when the
    solder melts. This reduces soldering defects to around
    1 bad connection in 100,000 solder balls.

    When a repair is finished, a 2.5D Xray machine can be
    used to verify the quality of the solder joints.
    Pictures are taken, using Xray energy, at an angle off
    the vertical axis. And any balls with a "popcorn" problem,
    can be seen in the picture taken with the Xray energy.
    I've never seen one of these in person, but our factory
    had one. Every large chip was verified with one of these
    (as part of closed loop process feedback). Eventually,
    once all the kinks are worked out of the manufacturing
    process, this might not be as necessary.


    A company in town used to do this repair here, but
    they charge $1000 per chip. They have this high charge,
    because their staff are mostly idle. And the company
    has likely long since closed up and moved. In Taiwan,
    where staff do this for a solid eight hours a day, the
    cost of repair is a lot lower.

    Depending on the ball count, pitch, and so on,
    there may also be "underfill" materials squirted
    underneath the chip. This forms a solid which helps
    control stress when the product is at its normal
    operating temperature. I know nothing about how
    you deal with underfill, when such a chip needs
    a repair. Underfill would be a popular solution
    for stand-alone GPU chips. (I don't even know
    what materials to use, so this is just an illustration.)



    Home computer repair people, they use the "oven
    method" to repair GPUs. Which is about as dumb
    and dangerous as it sounds. While the repair
    may seem to work at first, the track record
    of such repairs is not perfect. Temperature
    profile is completely uncontrolled - plastics
    may melt on items which were not intended for
    this sort of treatment. Proper repair with a hot
    air rework station is better, because the temperature
    profile is controlled during the entire operation. You
    can use the chip manufacturer recommended profile,
    when doing a repair.

    Paul, May 26, 2014
  17. Calia

    Calia Guest

    The timing of the single blink remains whether I use the
    battery or the AC power supply without the battery.

    I am googling how to reflow the motherboard and it looks
    like I have three major options (none of which are really
    all that good).

    1. Cover all fan ports & run the PC hot for 20 minutes.
    2. Disassemble & reheat specific chips (e.g., cpu).
    3. Disassemble & bake motherboard in the kitchen oven.

    None seem particularly safe.
    Calia, May 26, 2014
  18. Calia

    Calia Guest

    Calia, May 26, 2014
  19. It's not impossible to do SMT repairs, but it does help to have the
    right equipment and plenty of practice. Also, if you're replacing
    parts, it might be helpful to have a supply of known good
    replacements. Cannibalism from other motherboards works in
    desperation, but is not a good idea. I use a Chinese hot air SMT
    workstation that I bought cheap on eBay for about $80. Make sure you
    get a good selection of nozzles. The video you mentioned should have
    had some aluminum foil around the chip to prevent the hot air from
    melting nearby parts and plastic.

    While this may be above your present abilities, I suspect that
    throwing money at the laptop is not going to work because it will
    probably cost as much as the laptop is worth to fix it. Big and
    awkward 17" laptops, with only 1600x900 displays and a slow CPU, are
    not exactly in demand. In the past, I've removed the motherboard, and
    sent it off to a random reballing service:
    It usually cost me about $150 plus about $20 shipping each way. Add 2
    hrs of my labor to tear it down, and put it back together, and I'm
    well over the value of the machine.
    It's unlikely to be the CPU. I haven't seen a dead Intel CPU for
    maybe 10 years, and only a few older AMD Athelon chips that blow up
    when the heat sink is dislodged. The CPU is in a socket so you can
    easily replace the CPU. Photos:
    The big white socket is for the CPU, which appears to be an Intel
    2.0GHz P6100. Cheap.
    From your detailed description (thanks), it looks like 1 flash, which
    means "CPU not functional". More likely, it's one of the other chips
    holding down the address or data lines causing the CPU to misbehave. I
    can't tell from here which chip without poking my scope onto the
    address and data lines.

    One thing you can do is buy|borrow|steal a hot air SMT workstation and
    get some practice on this machine. Well, practice on some old boards
    first to get a feel for how much heat is needed and for how long.
    However, don't try to remove the chip. Just slop on a mess of paste
    flux, and heat it until the solder reflows. Maybe push LIGHTLY on the
    chip to get it closer to the PCB. If the astronomical signs are in
    your favor, you might end up with a usable board. If not, you won't
    be any worse than you started, and maybe you can do better on the next
    motherboard. Or just use it as a cat warmer:
    Jeff Liebermann, May 26, 2014
  20. The theory is that since the BGA chips use low temperature (bismuth)
    solder balls, it doesn't take much heat to reflow the solder. The
    reality is that without flux, the broken solder connections are
    unlikely to fuse together.
    The CPU is in a socket. Buy a cheap replacement on eBay and try it.
    That will melt all the plastic parts (i.e. connectors). Bad idea.

    There's a 4th option. Send it to someone with the expertise and
    Well, they're a step above the Xbox repairs that use a sterno can
    under the PCB to reflow the solder.
    Jeff Liebermann, May 26, 2014
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.