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generic notebook, soldered CMOS battery dead, what next?

Discussion in 'Laptops' started by Skier, Jan 2, 2004.

  1. Skier

    Skier Guest

    I have a generic noname notebook P233/64megs/3.2gig/CD etc. It has a
    soldered CMOS battery that is dead. Dumbest thing I have ever heard of.
    Put a battery that will wear out and permanently solder it into the mobo.
    What can I do? I have to set the bios info each time I start, e.g. time,
    date and power settings. The rest are OK. I also get a strange video the
    first time, with stripes and the video is offset. I think that has
    something to do with the battery too, because when I hit the start button to
    restart the video is OK.

    Is there any way to "clip" a good battery onto the bad battery, or do I need
    to de-solder the battery and resolder a new one. I have never soldered a
    motherboard before. I have a small 30w "stick" soldering iron, but not sure
    the point is small enough to not damage the parts nearby. Or, should I just
    live with the re-entering of the bios settings. Other than that, it works
    fine. I have one running Win98SE with a wireless lan card and another that
    is running Linux and wired to the network. The office was throwing them out.

    Thanks for any ideas
    Skier, Jan 2, 2004
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  2. I opened up a cheap calculator ($1.99) a while back, and I found its
    battery installed as you describe for your laptop. I thought I could
    deal with that when the battery went; and seems to me, inside your
    machine you'll find about what I find in my calculator.

    (Would I spend $20 worth of time to replace a battery in a $1.99
    calculator? Being me, I would.)

    So here's what I might do. Find an isolation transformer, or two
    transformers you can connect back-to-back to separate your soldering
    iron from the AC lines. Make an scr controller so you can regulate
    the hotness of your iron. On the iron side of your line, put two 470K
    resistors end-to-end across it, and connect the center junction of
    these resistors to your local ground. These are to bleed off any
    static charge on the iron to ground.

    Your local ground is a piece of metal fly screen or maybe a large
    sheet of conductive plastic, to work on. Your work sits on this and
    before you touch anything, you touch that ground. Which is earthed to
    real earth or to a heating or water metal pipe. There are safe
    devices like a wrist loop and a large resistor that you can use to
    ground yourself to your local ground. Do not do this with plain

    The purpose of all this is to protect your laptop from a hot little
    static spark that can kill it dead, while protecting *you* from an
    inadvertent connection to the AC lines.

    An incandescent lights dimmer probably will make a good enough
    soldering iron heat controller.

    Your soldering iron should have a small point on it, very clean. You
    can clean the point with brown paper bag material, which can be
    dampened. You are going to use 60/40 or eutectic (63/37) solder,
    *not* 50/50 plumbers solder. So find a controller setting that is hot
    but not *very* hot, which is the usual full-on soldering iron heat.

    Now you're ready to cast your dice, oops, tackle your problem. You
    want some small tweezers. Begin by making a sketch that shows which
    side of that battery is down, so when you replace it, you get the
    polarity right. I am sure you will notice the battery itself is not
    soldered; it sits under a *holder* that is soldered. Probably the
    center terminal of the battery is down against the board. So, latch
    on to one side of the holder, lift firmly, and touch the soldering
    iron to the solder there. The holder will lift and perhaps even come
    free. If you see more to improve your sketches, improve your
    sketches. Now try the other side, and in a couple of repetitions, you
    will have the battery free.

    Now for it. Could you possibly find a real battery holder for that
    spot, and enough space for it? Or, could you run a couple of
    insulated wires off to a space to the side, and put the replacement
    battery there? As you think about these things you are reviewing and
    improving your sketches so that you *do not* install the new battery
    connected backwards.

    Now look at the battery itself, which probably has a type
    identification on its base. Now go to a Shacky Radio and see what you
    can find that provides the same voltage -- a physically larger battery
    won't hurt if you can find space for it. While you're there, scout
    around for a holder of some kind that you can use.

    In older machines, you will sometimes find a holder for a couple of
    AA cells stuck in somewhere in the machine. These replace the
    original CMOS battery. You can do this kind of thing here, provided
    you do it right. If you can throw in a little design change so you
    never have to do all this jazz again, you want to do that.

    Now go home and put the thing back together. Maybe just like it was
    before but with a new battery. If you use the original holder, clear
    off the original solder and resolder with a *minimal* amount of solder
    added. Resoldering like the original unsoldering, is done quickly
    with a light touch, for you don't want to burn the board. If you go
    the simple replacement route, at least you know how for the next time.

    Your big risks are, 1) you kill the machine by static or bad
    soldering, i.e., not jeweler quality soldering; or, 2) you mess it up
    somehow else. I can't help you with all the possibilities. One
    possibility is, if you farm it out to a friendly expert, your expert
    may not be as expert as you need. And I have to warn you, if you
    follow my instructions accurately there still could something go wrong
    for which I cannot be responsible.

    Cheers -- Martha Adams
    Martha H Adams, Jan 2, 2004
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  3. Skier

    Ian Stirling Guest

    Way, way, way too elaborate.
    Use a grounded 25W or so iron.
    Connect laptop ground (exposed metal) to ground via a 1M resistor, and
    then go for it.

    You can usually simply snip the wires of the battery, so you don't have
    to solder directly to the motherboard.
    Ian Stirling, Jan 2, 2004
  4. Skier

    John Doue Guest

    I agree to keep it simple. I had a problem on a recent laptop working
    perfectly, the various LEDs stopped working because of broken soldering
    on a connector. I considered my choice: living with this problem (very
    unconfortable) or trying to fix it, with the risk that I would need to
    buy me a new laptop. After it tried to correct the problem with a simple
    iron from Radioshack, the laptop would not boot and I feared my next
    step was to pick up the phone and order a new laptop. But I decided to
    check my assembly, and connecting the video cable back did help! and
    solve the problem. ONe year later, my laptop still works to perfection
    and I am not considering buying a new one, plus I had the huge
    satisfaction of solving my problem.

    My bottom line: do it if and only if you accept the possibility your
    laptop will end up as a doorstep. And experimenting before "surgery" on
    a discarded video board or other would be a good idea.

    Good luck
    John Doue, Jan 2, 2004
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