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how to replace laptop fan?

Discussion in 'Misc Electronics' started by Allan Adler, Apr 9, 2007.

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  1. Allan Adler

    Allan Adler Guest

    How do you replace the fan on a laptop if you really cannot get an
    exact schematic for the particular model you have? In case you want
    to know the model, it is the one I asked about in another thread
    and got no replies to: Compaq Presario 3000 - model 3045US

    I don't know anything about repairing laptops. One can presumably
    find the approximate location of the fan since it must have an exhaust
    vent. One can then cut open the case somehow, if there is no way to
    simply open it at that place. How much does one have to worry about which
    fan one uses to replace it? After doing so, one can put the casing back
    that one cut out using epoxy or something.

    Alternatively, one can cut a hole in the case and connect a hair dryer
    with the heater turned out and direct the air from the hair dryer through
    a tube into the hole. Would these ideas work?
  2. One can then cut open the case somehow...
    If you want to cut open a laptop, give it to someone else. You'll create so
    much more damage than you're trying to fix.
  3. Allan Adler

    Allan Adler Guest

    Since posting this, I have actually received the laptop. So, I can actually
    try things. Also, I went into a computer repair place and talked to them
    generally about whether they use schematics when they open up a laptop.
    I was told that they don't, even with an unknown laptop, and that instead
    they have enough experience with laptops that they can usually figure out
    how to get them open. That is pretty encouraging, even if it is not specific.
    I don't intend to bring the laptop to such a shop since it would be pretty
    expensive to have them work on it. Instead, I want to try to find out how
    to get the thing open.

    The person who gave it to me told me that he tried unscrewing some of the
    screws but didn't get anywhere. I'll try also but if there are any other
    general tricks to know about for opening laptop, I'd be glad to know
    about them. Is there a book that explains how to do that?
  4. IN a lot of stuff, the screws don't really hold things together. There
    is plastic latching, or hooks or something. So you get all the screws
    out, and the stuff still doesn't come apart. IN some cases, what needs
    to be done isn't obvious until you get the whole thing apart, and
    at that point some of the plastic latches or whatever have been broken.

  5. Jasen

    Jasen Guest

    take out the screws, look for bits of plastic that un-clip and hide
    other screws.

    You will probably need to remove the keyboard fairly early in the game.

  6. Allan Adler

    Allan Adler Guest

    Thanks for all the advice. I think I should not do this myself. I think I
    can get a discount at a computer repair place. I can either let them replace
    the fan, if doing so is not more expensive than buying a comparable laptop,
    or I can just get them to show me how to get it open. The lesson itself would
    be worth paying for. I figure that if the fan has died, it might be prone to
    die: I've had PC's that I had to replace the fan in fairly often. So, it's
    better to know how than just to have it done.
  7. Allan Adler

    Allan Adler Guest

    I talked to the guy at the computer repair place today and brought my
    laptop. He didn't go into a lot of detail, but he explained briefly what
    I have to do, pointing to specific parts of the laptop. He says there are
    no hidden latches in general. He says to unscrew all the screws on the
    bottom, remove the battery and the various drives and, when all that is
    out, turn it over and use a flat head screwdriver to lift up the part that
    is between the keyboard and the bottom of the screen. I should be careful
    not to force anything (e.g. a little effort might reveal another screw to
    unscrew). Once that part is lifted, it will be possible to remove the keyboard.
    The fan will be located below the keyboard.

    Someone here told me I have to remove the keyboard. The computer shop's
    explanation is consistent with that, but sheds more light on how it is done.

    I haven't tried anything yet and will probably wait a few days. Any last
    minute advice before I try it will be welcome.
  8. Jasen

    Jasen Guest

    keep track of the screws, there may be different lengths and having to
    undo 20 screws because the last screw is the wrong length is a real

  9. Allan Adler

    Allan Adler Guest

    I waited until this morning to try to open up the laptop. Following Jasen's
    advice, I make little slips of paper and numbered them 1-20 or so and attached
    them to the bottom of the laptop with scotch tape. Then I made duplicate labels
    to attach to the screws as they came out. I was pretty sure that, contrary
    to the advice of the guy at the computer place, I didn't really have to remove
    all the screws and all devices plugged into the various bays, so I focused
    on the ones that seemed to be located in the relevant area. I tried with a
    flat head screwdriver to lift up the part between the keyboard and the bottom
    of the screen from time to time (call it Part A) and it kept getting easier
    as more screws were removed. Finally, it just came out. Then I tried to
    remove the keyboard. It is fairly flexible and I tried pulling on it from
    the top, which had just been exposed with the removal Part A. It was possible
    to get a couple of clips at the bottom of the keyboard to come out, but the
    space key seemed to be firmly attached. I removed another screw and it came
    out easily.

    I examined Part A and noticed that there were two threaded metal spacers
    that were the only things that attached Part A to the bottom of the laptop.
    I examined the corresponding places on the bottom and noticed that each of
    them had an arrow on the case pointing to the screw. So, in retrospect,
    it is now OBVIOUS which screws have to be removed to remove Part A: there
    are only two and they are the ones with the arrows next to them. I also
    examined the last screw I had to remove to take out the keyboard and saw
    that it had a symbol next to it. I had noticed both the arrows and this
    symbol when I was removing screws but didn't know what significance to
    attach to them. In particular, I thought that the symbol next to the
    screw I removed for the keyboard was a symbol for the motherboard, but
    actually, the rectangular symbol is a picture of the keyboard.

    In short, there are 3 screws that had to be removed and their locations were
    clearly indicated, two by arrows and one by a picture of a keyboard. I won't
    know whether this conclusion is completely correct until I have put the
    thing back together and can try again to take it apart by removing just
    those three screws. At the moment, there are several screws out.

    There is some dirt I might like to clean out on the underside of the keyboard
    and elsewhere. I'm not sure what to use. Maybe alcohol on a cotton swab or
    paper towel. But the main problem that remains is to remove the fan. It
    is mostly below Part A but it was still necessary to remove the keyboard
    because part of the fan casing is below the keyboard. The fan assembly
    has some screws of its own. Removing Part A exposed a picture containing
    instructions on how to remove the fan assembly: it clearly shows 4 screws
    to remove and then a particular metal tab to lift. Symmetry in the construction
    suggested that there ought to be a 5th screw to remove, but located under
    some electrical tape. I lifted the electrical tape and there was indeed
    another screw.

    So, I think I know what I have to do to remove the fan. I'm hungry now
    and will work on it later, but I first wanted to post details of this
    recent progress. All the screws I removed are attached to labels and
    have been placed in a sandwich bag, along with the unused labels,
    so I don't think I'll have any trouble picking up where I left off.

    The unexpected side effect of this progress is that now I would like to
    get my hands on some more laptops and try to open them up. I often see
    PC's thrown away on the street, but never laptops.
  10. Allan Adler

    Allan Adler Guest

    I still haven't removed the fan but will do so soon.

    The person who gave me the laptop suggests that, before replacing the fan,
    I make an effort to determine whether it is really the fan that is defective
    or the logic that controls it. Specifically, he suggests that:
    (1) It is probably a DC fan and probably runs on the exact DC delivered
    by the power supply
    (2) It should therefore be safe to try to run wires from the power supply
    to the fan to see if it spins.
    (3) If it does spin, the fan might just need a cleaning.

    While I'm working on removing the fan, I'd be interested in other people's
    opinions of these suggestions.

    Apparently, the laptop also has a damaged sound jack. That was caused by
    someone tripping over a cord and ripping something out. So, I can try to
    repair that too. For me, this is terra incognita.

    A while ago, I checked out a book on laptop repair and upgrading from the
    library. It was an enormous book that talked a lot about different kinds
    of components but wasn't easy to read. It seemed to have been written for
    someone who basically already knew a lot about laptops but needed a reference
    work. I never found a part that explained how to get started, for example.
  11. Jasen

    Jasen Guest

    Replace the fan, fans that begin to work again after minor service
    soon fail again.
    If there's no circuit board damage that may be possible.

    unsoldering components from motherboards is tricky, you should
    defintely prctice on some junk first.

  12. Allan Adler

    Allan Adler Guest

    I don't think I have any documentation for the laptop. Anyway, this evening
    I successfully removed the fan. Then I considered the possibility of runningd
    the fan from the power supply. The 3 fan wires are red, blue and orange and
    terminate in a tiny connector that plugs into a matching socket somewhere
    under Part A. It didn't seem very feasible to try to feed wires directly
    into the socket, but maybe it can be done. Anyway, I plugged it back in.

    With Part A removed, the usual power button is gone but it was easy to find
    the button under Part A that the power button really pushes. So, I tried to
    push it and run off the battery to test the fan. Nothing happened. I considered
    the possibility that the laptop has some way of knowing whether Part A has
    been removed. I looked around and found something I could push. I think it was
    just something that gets pushed by something that gets pushed when the laptop
    is closed, hence is irrelevant; anyway, it didn't help. I couldn't turn it on.

    I decided to look at the fan more closely. I removed three screws that held
    the fan itself in its case and then easily removed the fan. Inside the case
    were three little pieces of some kind of fluffy material that I first thought
    were dust bunnies, but now I think they used to be a single piece of some kind
    of thick matting that sat in a particular place in the fan casing and got
    shredded and dislodged. I removed them and put the fan back together. Then
    I put the keyboard and Part A back. I couldn't remember whether the bundle
    of wires to the fan went above or below the fan casing and improvised various
    arrangements until I found one that seemed ok, but I'm still not completely

    Anyway, once it was back together, I tried running the laptop off the
    power cable. The green light went on indicating that it was plugged in
    and then a moment later a yellow light at the opposite end of the laptop
    (i.e. where one's wrists are when one uses it, at the edge) went on. Next
    to that yellow light was an icon consisting of an arrow pointing to what
    looked like a battery.

    So, maybe it was complaining about something having to do with the battery.
    I had, in fact, removed the battery, after a few unsuccessful attempts to
    do so due to not having unlocked it, and then put it back in.

    I should perhaps also mention that the laptop doesn't latch closed. That
    seems to be due to hooks from the top that are supposed to fit into holes
    on the bottom at the wrist end having broken off. In the hole on the right,
    I noticed something showing that looked like a piece of metal. With the
    laptop turned off, I poked it gently with a small screw driver and it fell in.
    When I took out the battery, it fell through one of the holes that is used
    to hold the battery in place and I removed the piece. I looked pretty carefully
    at the battery and I'm pretty sure it is not a piece of the battery. It is
    made of copper and looks like it might be some kind of lead, but it could
    just as easily be part of some kind of latch. Later I took another look at
    the hole I first looked in and saw more metal pieces, apparently stuck
    together. I poked again and the part fell down, but returns when the laptop
    is turned over. There seems to be no way to get it to fall down through the
    same battery hole I extracted the first piece from. When I get better at
    opening up and taking apart the laptop, I might figure out how to get at it.

    In my earlier attempts to turn on the laptop, I had not put the screws back
    in. I did so and tried again, but the results were no different: the yellow
    light at the front with the icon showing an arrow pointing to what looks like
    a battery went on and it didn't respond to trying to push the on button.

    One final note: when the laptop was given to me, it worked. It ran Linux
    until the temperature reached 84 C (or whetever) and then turned itself off.
    Since that is supposed to be a safety feature, to protect the CPU and stuff,
    probably the laptop is ok. But I thought I should mention it.
  13. Allan Adler

    Allan Adler Guest

    [battle of the battery deleted]
    Last night I showed a friend of mine the laptop. I opened it up again and,
    at his suggestion, I pressed the button on the motherboard. To my surprise,
    it turned on and worked fine, Linux and all. The fan also works: my efforts
    described above were successful. Whether the temperature problem is gone
    remains to be determined. The reason the machine didn't turn on earlier when
    I tried to turn it on when it was open is that the battery was depleted.
    The reason it didn't turn on earlier when the machine had been put back
    together and closed up is that the piece containing the external on/off
    switch was strained in such a way that the external on/off switch did not
    make physical contact with the on/off button of the motherboard, so one
    was in effect pressing air. If one presses on the case to bring them
    into contact, and then pushes the on/off switch, it works fine.

    So, now I just have to do the following:
    (1) Figure out why it is not making contact and correct the problem.
    (2) Make sure that the temperature problem is gone.
    (3) Repair the PCMCIA, which got torn out when someone tripped over
    a cord.

    It is extremely useful to learn that sometimes all you have to do is open
    up a device, maybe reseat some of the parts, and it will work. This was also
    demonstrated on another computer last night that I had thought was completely
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