T30 "Critical Low-Battery Error" will not boot

[givtechnicalhelp]

Thanks......Rotter....Actually I was strugling with this problem last one month....


Finally I Found Rotter's First and Great post..here...
..
Now the problem is 95% solved .I have to get an FET for Remaining 5%.....

Rotter I Really Appreciating You........For Your Great Job!!!


Love You Rotter & This Forum........

[Rotter]

Hi,
Good that it helped you, i too had that problem quite some time in which i was searching the internet for information. But since i didnt find what i was looking for i had to look into it myself and it paid off.
It seems that it is not a common problem but isn't too rare either, so hopefully people with that problem have it easier now to resolve it.

Greetings
Rotter

[robocop]

Hello Rotter
I think I might have the same issue as you reported in this interesting post.
My issue is reported here: http://forum.thinkpads.com/viewtopic.php?t=63193

I have checked all inductors, and they all are OK and well attached to the MB, the battery is charging but very very slow. Do you think that I could be affected by this issue as you reported with the transistor?
My electronic courses date from very long ago, and I don't know anymore how I can check if the transistor is working or not? What do you recommend I should start testing? Thank you in advance

[Rotter]

Hi robocop,
That could possibly be the same problem, but the t23 mainboard has not the same Layout than the t30, so it would be nessecery to locate all the parts again which could be a bit work. But there sureley will be similarities between the boards which can make it easier, so it would be a good thing to locate the battery charger ic and the power supply controller. I will look at some pictures of t23 MB to see if i can find something.
Greetings
Rotter

[j2k]

Rotter, wow, this is huge. You have given me renewed hope that my t30 board can be salvaged!

So, using the image t30bottomg6fr6_2.jpg, I have determined the following:

At point 1 --- 2.0V
After unit 2 --- .7V
At terminal b on unit 4 --- .1V
At point 5 (aka terminal c on unit 4) --- 1.6V
At post after unit 7 (you labeled it <-3.3V) --- 3.3V
At point 8 --- 0.0V

On the top side, using image t30topj5im4.jpg, I found the incoming voltage to the 10 Ohm to be 16.6V, which is what my AC adapter is providing.

I'm not sure how to check resistance of the top and bottom side 10 Ohm resistors without taking them off of the board (which I am loathe to do, unless it appears necessary). I don't have a lot of experience with this sort of thing.

What does this all mean??!

Just to recap from earlier posts: t30 runs perfectly on charged battery, but will not even attempt to boot if dead battery is installed and AC adapter are plugged in, and will attempt to boot with only AC adapter plugged in but will shut down after ~10 seconds and report "error 190 Critical low battery..."

Thank you so much for all of your help! Wow, you are a genie!

[Rotter]

Hi j2k,
2.0V at Point 1 means that the Zener Diode is dead.
The 0.7 Volts indicate that the Transistor / Mosfet 4 is dead also (shorted between Gate and Source),
To replace them you definitely have to remove the System Board.
Could you measure the Resistance from The Power Connector (+) to Point 1 (should be about 12 Ohms), if it is not, the 10 Ohms Resistor most likely is dead too (which is most likely the case).
Greetings

[rolando_574]

[Hello! . My A31 present the same issue. I want to replace the transistor that you mention but i can't find. The motherboard is like a t30 board. If you need photos i can do it. Please help me.

[j2k]

I have not yet made the attempt to replace the components Rotter identified on my board... but I do plan to do so soon. I'll post here regarding the results.

[rolando_574]

Thanks for Reply J2K, I'll post here some photos about A31 motherboard for if anybody identify where is the transistor.