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Toshiba laptop continuing problems model A205-S5804.

Discussion in 'Electronic Repair' started by klem kedidelhopper, Jan 4, 2013.

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  1. This is my wife's laptop which I posted recently. It had somehow
    mysteriously "acquired" an unknown CMOS password which was preventing
    me from getting through post and into boot. I believe that it was Jeff
    who found a thread on another group which talked about this very thing
    and offered a procedure for resolving it. I performed the procedure
    and it cleared the password, (or whatever it was that was blocking the
    boot sequence). I was very grateful for that help. After doing this
    though the computer seemed flaky, freezing at times,etc, So we dumped
    the hard drive and reloaded Windows. Now it seems to work fairly well
    on battery, however most times, (but not always) oddly plugging the
    power supply in will cause the computer to freeze. It is then
    necessary to do a hard power down and boot back up with just battery.
    This has always seemed to work. Most times though if the power cord is
    connected it will either not boot, or it will boot, let you do a
    couple of things like maybe get to a Website, and then perhaps a
    couple of more keystrokes and then it will freeze. I have repeated
    this problem many times now since clearing the phantom password and it
    seems to be consistently tied into operating on AC power. Does anyone
    have any ideas about this? Thanks, Lenny
     
  2. I'm reminded of the joke about the patient raising an arm above his head and
    saying "It hurts when I do that, doctor!"

    "Well, don't do that!"

    Obviously you can't run the computer solely on battery power.

    Can you get ahold of a new power supply? It's possible the supply you have is
    noisy, or generates a transient when plugged into the computer.
     
  3. chuck

    chuck Guest


    Have you cleaned out the cpu heatsink fins or is the cpu fan not
    working? The cpu runs faster when plugged into power and might be
    overheating. Chuck
     
  4. When I had it apart to reset the Eprom the fan and heat sink looked
    pretty clean. I think I'll look at the power supply output on the
    scope and while observing it I'll load it and see if anything happens.
    If you guys have any more ideas though, I'm all ears. Lenny.
     
  5. tuinkabouter

    tuinkabouter Guest

    Did you replace the backup battery?
     
  6. I didn't because the time and date and all parameters seemed to have
    stayed up. Lenny
     
  7. Guest

    It may be screwed up. For now, to deal with it set the power balance the same for AC and battery and see what happens.

    Almost all laptops dim the display and change the processor mode from performance on AC to economy on battery. This is the main thing that could be freezing the OS. If it was rebooting, shutting down or something then that would be different. It is looking for a power configuration that is likely not there.

    On mine I can control it from Windows, but not all machines will have that and if you reload or reset stuff, this config data coulld be missing or corrupt. It can be in BIOS or the OS, or both. (kinda like control panel)

    Go back into setup, find power management. If you can find in there ANYWHERE that differentiates between battery power and AC, set them identical. Or turn the whole feature clean off if possible.

    Incidentally, before proceeding, will it boot up from AC power ? If so, does DISconnecting the AC power cause this as well ? If not, you set everything to run as if it on batteries all the time. In fact that is probably best anyway, unless it dims the screen and makes it hard to see. I only run mineon battery in the dark because otherwise it is too hard to see.

    Hell, I guess a solar battery for it would just about fix me up woulntit.
     
  8. I looked in Bios and can't find anything to do with power management
    or battery power etc. I don't think it's an option on this version.
    Could it be called something else? Lenny
     
  9. BTW this never happens when you disconnect the battery. Only if you
    connect it while you're using it. Lenny
     
  10. Guest

    "BTW this never happens when you disconnect the battery. Only if you
    connect it while you're using it. Lenny "

    AHA ! There are regulators all over the place and most depend on electrolytic capacitors.

    See where I am going with this ?
     
  11. I looked in Bios and can't find anything to do with power management
    The controls for power management are usually available from the operating
    system. Which OS does this computer run?
     
  12. mike

    mike Guest

  13. mike

    mike Guest

    This doesn't sound exactly like the problem, but it's a similar issue.
    I have a Dell with a (formerly) bad battery...long story...the laptop
    charge light blinks an error sequence.
    The laptop encourages me to replace the battery by this behavior.
    The battery will only charge with the computer off.
    The computer always runs off battery, even when plugged in.
    The only way to run on AC is to REMOVE the battery.
    Battery issues can have non-obvious symptoms.
     
  14. A few observations and history:
    Yes I did have to clear the bogus CMOS password problem by shorting
    the two points on the mother board going by the procedure that you had
    sent me the link to Jeff. And I never had this "freezing" problem
    before the password issue. However it's more complicated than that.

    Also I did find the power balance information that Jurb suggested. It
    wasn't in BIOS but in control panel. There were three fields, and I
    made them all identical but that didn't seem to make a difference.
    They addressed dimming the panel on battery and two other things.

    Further, after clearing the password a few weeks ago, the computer
    seemed unstable. So we copied a few needed files to a memory stick
    and my son dumped the hard drive and installed Windows 7 from a disc
    he had, that among others had an OS version on it for "Toshiba". This
    computer was given to us so we never had a rescue disk of any kind to
    go with it, and unfortunately I don't recall what OS was in there
    before he dumped it. So I don't know when this "freezing" problem
    actually occurred, after clearing CMOS, or after he installed the new
    operating system. I also don't know anything about the disc he used,
    like where it came from or even if it was OEM etc.

    Another observation: I always plug the AC in first. Then I connect the
    19VDCjack to the computer. If I disconnect the the DC plug it's done
    with the power supply still connected to 120V as well. The computer
    will never freeze when disconnecting the DC plug, rather it's only
    when connecting it to the computer when it's running on battery
    alone.

    This afternoon I looked at the power supply on the scope. This supply
    is rated 19VDC 3.95A. With no load the output read 19.2V. There was a
    small 20mv.low frequency triangle waveform present. Approximately
    every 6 usec. there was a 160mv. spike. I took a better look at the
    spikes. They actually looked like ringing pulses with a width of about
    80 usec. I then loaded the supply with a 4 amp resistive load. The
    voltage dropped to 18.9V and the spikes increased in amplitude to
    about .900V. every 6usec.

    Now given a SMPS that's charging LI-ion batteries I don't know whether
    or not the above constitutes a "noisy" supply or if these kind of
    aberrations are to be expected. So I figured I'd substitute my bench
    supply with linear regulation as a test.

    I set up 19 V with a current limit of 4A. I then connected this to the
    computer and after hitting power on I immediately noticed the current
    meter surging to 100ma. every second or so. The computer booted up
    and worked for about 2 minutes and then just shut down. Afterwards I
    was not able to get it to come back on with the bench supply. Thinking
    that trying to use a linear supply to power a device with LI-ion
    batteries probably wasn't the smartest thing to do I then connected
    the suspect Toshiba supply and the computer booted up and never froze
    during a 1 hour period of using it.
    I'm chasing a ghost.

    So now what I do know is that the power supply does spike up to .900V
    when its fully loaded. I don't know what the actual load of the
    computer is, and since I couldn't simulate this I figured I'd go for
    worst case. However I think that I can assume that it must also spike
    somewhat when connected to an already powered on computer as well.
    Whether or not it's supposed to do this or if this is my problem is
    anyone's guess. It's pretty clear that the computer does not like to
    run on pure DC though. Lenny
     
  15. mike

    mike Guest

    Not clear what that means. I've seen universal install disks for XP.
    They address the OEM activation issues, but probably don't have all the
    drivers you need for every version of every Toshiba computer ever made.
    Assuming you have a quality scope and probes and know what you're doing,
    0.9V sounds like a lot, but probably not killer.
    I've seen some wacky designs, but never seen a laptop that wouldn't
    run off a DC bench supply.
     
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