[PLUG] Possible fried laptop...

Eitan Tsur eitan.tsur at gmail.com
Tue Dec 23 07:03:12 UTC 2008


Ok, turns out it just had some weird state in the CMOS.  Re-popped the CMOS
battery, shorted the contacts on the holder this time to discharge any
capacitance, and reassembled.  The whole thing worked, more or less, and
boots just fine now.  Only issue I have now is that the system does not
detect when the lid is closed anymore.  It worked before, so I'm guessing
there's some BIOS setting that affects it.  Anyways, thanks for all your
advice.  Really glad it wasn't fried, and next power outage I'm unplugging
it and all my other valuable unprotected-by-UPS electronics.

On Sun, Dec 21, 2008 at 10:20 PM, Eitan Tsur <eitan.tsur at gmail.com> wrote:

> Ugh...  Not exactly the news I was hoping for, but I've already popped out
> the battery, put it back, popped it out AND the CMOS battery, replaced them,
> reseated the RAM, and a host of other things, and still nothing.  I'll have
> to wait until tomorrow to verify that it's not mysteriously fixed itself and
> then strip it down to the motherboard to try to isolate the problem.
> ...Noone's ever heard of a CPU frying due to power fluctuations, have they?
> (It's the only other easily-replaceable component in the system, and
> although 1 GHZ P3's are rare, it's not the end of the world if that's what
> blew.)
>
> Oops... another power outage.  Thank god for UPS's.
>
> Regards,
> -Eitan-
>
> PS: god I hope this one doesn't last all night...
>
>
> On Sun, Dec 21, 2008 at 10:10 PM, Keith Lofstrom <keithl at kl-ic.com> wrote:
>
>> On Sun, Dec 21, 2008 at 06:38:53PM -0800, Eitan Tsur wrote:
>> > Hi all,  so I lost power for a couple hours today, and my laptop was on
>> > during the outage.  I shut it down, plugged it in, and waited until the
>> > power came back to use it again.  Since then the power has come back on,
>> > however the laptop will no longer POST, and the power light flashes.
>>  This
>> > has never happened before, (light flashing or no POST condition,) and
>> seems
>> > to be unaffected by being on wall power or not, with or without the
>> battery
>> > installed.  If anyone has any thoughts on what could cause this sort of
>> > situation, please let me know.
>>
>> The first thing to check is whether the AC adapter produces the
>> right voltage.  It is difficult for a power line upset "reach
>> through" the AC adapter and zap the laptop.  If it somehow did,
>> it is even more unlikely for the adapter to produce normal
>> voltage afterwards.  There is a lot of power regulating circuitry
>> in most laptop adapters, and I would expect that to blow first.
>>
>> However, what CAN happen is that the line power can bounce on and
>> off in the wrong way, the output of a poorly designed adapter can
>> bounce up and down with it, and this can stress the power input
>> circuitry of the laptop, wreaking havoc.  This should not happen
>> with well designed power hardware.  Sadly, at most places I know
>> about the power supply is where they save pennies on components,
>> and save salary cost by hiring second rate engineers.  Power
>> supply behavior under funny line conditions is a not banner spec
>> or a driver of purchasing decisions.  I have seen two battery
>> charging circuits fail on 1997-era laptops, necessitating depot
>> level repair.  IBM was great for these fixes, Levono not so
>> much, Dell used to suck horribly.  But things change.
>>
>> If it is a zorched power supply on the laptop motherboard, the
>> whole motherboard will need replacing.  You will have a hard
>> time isolating and identifying the blown semiconductor (s),
>> figuring out the part number, and finding a replacement for sale
>> somewhere, because they probably don't manufacture it anymore.
>>
>> That said, Google is your friend.  Look to see if others have
>> had the problem with your model number.  And eBay is your friend;
>> a lot of people break screens and other components that aren't
>> the motherboard, so you can usually find used replacements cheap.
>>
>> My bet on the broken component is (1) AC adapter, (2) battery,
>> (3) motherboard.  It helps to have spares for (1) and (2) anyway.
>>
>> Keith
>>
>> --
>> Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
>> KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
>> Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs
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>
>



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