T61 power status changing when unplugging from plug

[hoax32]

when i unplug my t61 from the power jack it normaly switches from plugged in to batery power.
but when i unplug it from the wall before unplugging the charger from the T61, the screen "dimmens and brightens up" back and forth in a loop and it switches the power state to "plugged in" back back to "not plugged in" also in a loop.....until i unplug the unplugged charger from the laptop - any idea what this is?

thanks ahead of time!


EDIT:
--------------------------
i figured it sounds to confusing so here is a more simple explenation:
When i unplug the laptop from the power jack, it does exactly what its supposed to do - screen goes dimm and the charging light turns off.
But when i unplug it from the wall first, it switches back and forth between charging and not plugged in. [it doesnt stop unitl i unplug the charger while its on - unplugging while of wont make the charging light go away until i turn it on]

tried different battery - no change

[SafeHarbor]

This may be coming from left field, but does it do it when using a partially discharged battery? I'm guessing that the circuit to the power supply may be getting some sort of capacitive feedback- that's it probably NOT supposed to be getting- from the power brick and wiring that's confusing the battery circuit in the ThinkPad. I think I'd try another power supply, but if still does it, it may be a bad diode or something like that.

[hoax32]

thanks for the reply!
New things i figured out:

Uplug charger from wall first while laptop on = "charging/not charging" loop
unplu charger from laptop first while on = everything normal
unplug charger from wall first while laptop off = CHARGING LIGHT STAYS ON UNTIL I TURN THE LAPTOP ON
unplug charger from laptop first while laptop off = everything normal
plugging in the charger [DISCONNECTED FROM WALL 1 SECOND AGO] = TELLS ME ITS CHARGING!!!???

basically the loop happens whenever i disconnect the AC adapter from the wall first
[doesnt matter if the charger is already connected to the laptop or if it's being connect it to the laptop right unplugged it from the wall]
Meaning - the AC adapter need to have some current/charge left in it to cause this loop.
If i leave the charger unplugged for 15 minutes and THEN connect it to the laptop while it's DISCONNECTED from the wall, the charging light will stay off.

also - when the laptop is OFF and i disconnect the plug from the wall first and then disconnect the plug from the lapop, the charging light stays on until i turn on the laptop.
But when i disconnect the charger from the power jack first, then the light does what it is supposed to do and goes off.

is it the laptop or the charger - what do yall think?

[hoax32]

ok i tryed different chargers / batterys - no change!
Everything is fine when i unplug the charger from the laptop first.
But unplugging it from the wall first give sme flase charging indications....
bothers me so much!
what could be causing this?

[cadillacmike68]

If you will apply a little patience you'll notice that the looping w/ charge indicators will eventually go out. There is residual power left in the AC adapter when you unplug it from the wall. That's why it loops or the charge light stays on for a while after the AC adapter is unplugged from the wall without disconnecting the round plug from the computer first.

[hoax32]

Thanks for the reply!
a Few questions:

1. - why doesn't this happen with my other 2 T61's with the same charger / battery
2. - the looping does not stop even 1 hour later until i reset every connection and unplug from the back first.
3. - this did not happen before - just noticed it recently - how come?

I mean, if it does not happen to my other laptops and it's not the parts then my GUESS woud be a power problem inside.
A power brick simply does not have enough energy to cause this loop for over and hour and not do this on another T61

[cadillacmike68]

Is this the same T61 that you are always overclocking as discussed here: ?

http://forum.thinkpads.com/viewtopic.php?f=29&t=106497

Is it only this T61 regardless or the charger or battery installed?

You're correct, it shouldn't carry on like that for more than 30 sec to 1 min. Something's wrong in the T61 in the power area. If it's your overclock baby, then well, you just got your second indication of why most of us don't do that.

[hoax32]

no
it's a T7300 T61.
Not overclocked.

[cadillacmike68]

In that case the T61 has a fault in its internal power interface.

[hoax32]

any idea what part it could possibly be?
I am willing to do some minor soldering if required.

[cadillacmike68]

I have not taken my T61s apart yet, except to add memory or change the HDD. There is a link to the T61 HMM is on this forum somewhere though.

[hoax32]

I have not taken my T61s apart yet, except to add memory or change the HDD. There is a link to the T61 HMM is on this forum somewhere though.

ive taken mine apart quiet often....I just did it yesterday but I couldnt find anything visually wrong with it.