power issue

[foo55]

i believe the problem with my thinkpad (which is a t21 i believe) is that either the jack you plug the adapter into is broken or the ac power brick itself is messed up. when i plug it in the charge light on the laptop does not come on and i cant run the laptop on ac power.

im wondering what i could do to check to see which one is the problem? i believe id have to solder the ac jack onto the motherboard and im not very good at soldering things.

thanks so much for any help

[pianowizard]

My T23 has a similar problem. Every once in a while, when I plug in the AC adapter, the battery LED won't come on, and within Windows XP Pro, the battery indicator in the system tray says that the laptop is on battery rather than on AC. However, the battery is actually charging perfectly fine -- I know because the battery's charge percentage actually goes up over time.

So, I suggest that you find out whether the AC adapter gets warm (which would indicate it's working), and whether the battery indicater in Windows shows that the battery charge is increasing over time.

[rkawakami]

im wondering what i could do to check to see which one is the problem?

The easiest way to determine that is to go out to Radio Shack or Home Depot and get yourself the cheapest digital voltmeter that measures voltage (AC and DC) and resistance and takes standard batteries (usually 9v). You can probably find one for around $25-$30. You can then use it to see if the AC adapter is outputting the correct voltage (16VDC). Measuring the power supply to see if it is providing the rated current will probably be beyond the capability of either the meter (most low-end meters cannot measure current) or your electrical skills (since you have to construct a cable or adapter to place the current meter "in-line" with one of the power leads). If the power supply measures the 16V that it should, then mostly likely the problem is within your laptop. I believe that the power jack in the T series is actually plugged into the motherboard and not soldered. I had one of mine opened up awhile ago and seemed to remember seeing this. If I'm wrong, I'm sure somebody will correct me on this. Assuming that you can disassemble the laptop enough to remove the jack and also to locate one cheap enough on eBay, that would be the next thing to check/replace. The Hardware Maintenance Manual contains detailed drawings which will help you disassemble the laptop:

http://www-307.ibm.com/pc/support/site. ... IGR-4UYM3F

edit: And here is a link to an eBay auction for the DC power jack:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 8738432710

[rixter]

Well I suddenly have a power issue on my T23 and so I do the obviouse and search the forums lol. My T23 says the battery is dead 0% but the laptop is not shutting off the battery light is blinking etc... But the laptop is running fine so I dont think I need to run a multi meter on it. Anyone ever seen this before.
PS the battery is not charging

[pianowizard]

My T23 says the battery is dead 0% but the laptop is not shutting off the battery light is blinking etc... But the laptop is running fine so I dont think I need to run a multi meter on it. Anyone ever seen this before.
PS the battery is not charging

I saw this issue before on a T21, after updating the BIOS. By reverting to an older BIOS, the problem went away!

[vlyne]

There are two circuits and contacts that are used for the battery; one for monitoring and one for power. So in the case where one goes out you can get confusing signals as to what's going on. In this case it appears as if the monitoring circuit is out. Possible checks are:

1) Battery electronics
2) Battery contacts (take out and put in the battery and/or check the cleanliness of the contacts).
3) Fuse associated with the monitoring circuit - check recent thread for Ray's posts on the subject. It may be the fuse marked "F" in Ray's image.

Cheers

[rkawakami]

3) Fuse associated with the monitoring circuit - check recent thread for Ray's posts on the subject. It may be the fuse marked "F" in Ray's image.

That's possible, although I don't know where the power monitoring circuit is getting its information from. According to the circuit probing I just did, the picofuse is also connected to the positive terminal of the battery. The other side of the fuse appears to go to a MOSFET (Toshiba TPC8002).

From looking at the T2x HMM, the battery troubleshooting guide says to check the resistance between terminals 4 and 5 of the battery pack. Assuming for the moment that pin 4 is the monitoring pin, then that pin is connected to what looks like a chip resistor, which in turn is connected to the TPC8002 MOSFET.

[vlyne]

Thorough as always Ray!

I'm guessing the picofuse is there to protect sensitive chips such as the MOSFET. Hopefully it's done the job.

Any idea what's inside the battery in terms of electronics?
Cheers

[rkawakami]

Well, if it's anything like what's inside the 600 series battery...

http://www.milnoc.com/TP600Battery/Inside.html

then there's an intelligent charging/monitoring circuit board. I haven't seen the insides of the T2x/T30 battery yet but I would assume that it's pretty similar.

[vlyne]

Excellent dissection! It's a fair bit more sophisticated than I thought. A lot more to go wrong as well! The thermistor and circuit protector are obvious candidates. I wonder what sort of information the EEPROM (marked "C") stores and how one resets it. I'm now convinced that batteries could be major issue!
Cheers