T23: Problem is the charging circuit

[alamin104]

Hello
I am in serious trouble with my T23. Its not charging the battery at all. I have tested the battery with another T23 of a frnd. The battery is ok. I also measured the charging voltage across terminal with multimeter which showed almost zero. Then I opened the motherboard trying to point out the faulty component. I checked all the fuses along with the inductor coils in the charging circuitry but everything seemed ok. Anyone has any idea which parts is causing the prb?
Any one can help me? Any one has schematic diagram of T23 motherboard? How much should I pay if i decide to change the motherboard?

[rkawakami]

Curious that you should post this because I have just tried to repair a T23 with a similar type of problem. My system did not work with a known good AC adapter by itself. As such, it did not charge the battery either. It would work fine with a battery alone. In my case the fuse next to the 4-pin connector which goes to the DC power jack was blown. I found what I thought is a replacement (Littelfuse 24V 7A part # 0429007.WRML from Mouser.com) and the laptop now does work with the AC adapter, however there is a burning smell after about 3 minutes of operation. So my problems are just beginning . Heat and smell appear to be coming from around the docking port connector. The 7A fuse that I replaced has not blown yet but probably will if I keep the system on for any longer.

I do not believe that schematics for any Thinkpad exist outside IBM/Lenovo's walls. I have asked for them before here in these forums and have come up empty. The cost of motherboard replacement varies. You can find many of them on eBay starting from $25 to up around $100 USD. The major problem in your case would be to also find a seller willing to ship to you.

For troubleshooting this type of failure, you should probably start at these questions:

1) Can the laptop be powered only with a known good AC adapter (no battery installed)? If yes, then the 16V is getting to the motherboard and most power systems are good. If no, then check:

• a) Continuity of wires in the DC power jack assembly.
  b) Fuse next to where DC power jack assembly plugs into the motherboard. The 7A fuse looks like a grain of rice; there are also other fuses which look like flat green 'plates'; make sure you check those too.

2) Can the laptop be powered only with a known good battery? If yes, then most of the power systems are working. If not, then check:

• a) Fuse next to the battery terminals. This one looks a little different than the 7A fuse near the DC power jack. Taller and looking more like a 'block'.

If these things don't work for you, then my last suggestion is one that I may have to perform with my burning system:

• Compare voltages at various points on your motherboard to your friends motherboard.

With no schematics to go by, this is the only thing I can think of which may help you locate the problem.

[MadMikeSS]

It's interesting that I should come in here after a while of not actually checking this forum and find this particular thread right at the top. Last few days I have noticed that my battery level had been dropping and was down to 93%. Usually the charger kicks in by 95% and keeps it topped up. But it wasn't rising. Also I noticed that the battery indicator light was lit but not flashing at all as it usually does when it's charging. So I decided today to run the battery out completely and then try and see if it would charge up again. So far it appears to be charging back up but the battery indicator light is not flashing like it normally would while charging so I'm getting a little concerned about the charger or the battery at this point. Any ideas?

Well, since discharging the battery and letting it charge up again, it appears to be functioning correctly again and charging up like normal along with the battery indicator flashing as it used to. Odd. I was about to buy a new battery too.

[alamin104]

My T23 works fine with the AC adapter.
It aso works with a charged battery.
The problem is, i cannot charge the battery in my T23.
I have tested my battery with another T23 and it was charging fine.
Then I measured the charging voltage in the charging terminals which showed zero V.
I opened the motherboard and tested different fuses and inductors but found ok.
The circuit is too complicated for me to trace and locate the faulty component.
Is there anyone who can help or give me a link where i can get some hints.