T40(p?) will not charge, but will run from AC or battery.

[RobbieThe1st]

I have a problem: My T40(p?) will not charge. It will however run fine from AC or battery, and I am using it to post this message. A few days ago, I replaced the power connector in the back with a no-name brand one that worked which I got off Ebay. A couple days after that happened, I was in the car, using the laptop and charging it off my DC charger, when I noticed that things were smelling hot. I found my charger was quite hot, and the electrical tape I had wrapped around it was what was smelling. I unplugged it, and ran my laptop off battery for a while, letting things cool down.
Anyway, after a few minutes, I went into the house, and plugged my laptop in. I was reading some stuff on my laptop for a while, and perhaps half an hour later, after having a little trouble with the AC connection(wouldn't stay connected, computer still showed it was running off DC), I unplugged it for a few minutes, and ran off battery. Anyway, a few minutes later, it was dinner time, so I plugged it back in and went to dinner. I estimate it was down to perhaps 75% by then. When I came back, it still was at the same percentage, and had not gone up, even though it was connected, and the lights were blinking like it was charging.
Over the last couple days, after I figured out it was not charging, I took it apart and started testing things. I found out that the insulation on the new connector on the positive connection was broken, and the little fuse(or perhaps resistor) was charred on one side. I bent the connection a bit out of the way, and put electrical tape on it to protect it from further harm.

I found one fuse which has a very high OHM rating, and appears to connect the battery with the charger - On one side, there is ~16V, and on the other, ~11.5 from the battery(same voltage as between the battery's prongs).

I tried testing things by shorting it temporarily, and got little sparks, but the battery voltage did not change at all. I did manage to put some char on the top of it though...

Here is a picture of what I am talking about:
http://robbiethe1st.ktserv.com/images/IMG_3079.jpg (No markings, 1.65M)
http://robbiethe1st.ktserv.com/IMG_3079_SMALL.JPG (Markings, 640X480, 75kb)
Note that [1] is the fuse which contacted the + lead of the AC connector,and [2] is the one which seems to connect AC and battery.
Also note that all three fuses at [1] are at .4OHM, and [2] is at 1.5M OHM.
One other bit of information: when plugged into AC, with the battery removed, the + and - prongs read 1.5V.

I need some information on what the appropriate thing to do is. I figure I can solder whatever needs to be soldered, but as I sort of need this computer in working order, I am not going to go hacking away at it until I know exactly what needs to be done to get it fixed.

Note that in my subject, I wrote T40(p?), and that is because this machine has parts from a T40 and a T41p, and I don't have the motherboard model number handy. I also can't supply you with a model number for the computer for the same reason.

Edit: Oh yes, one more thing: I have access to another T40 laptop, so I can test my battery, but I cannot take parts off it as it is my mom's laptop. Last night I switched the batteries, and while I don't know how my battery is doing, I know that the other computers battery is not charging in this computer, but it does run off it, just like mine.

I also have a few spare parts, including a motherboard(from the t41p, so I should be able to get whatever parts are needed.


Thanks,


-RobbieThe1st

[RobbieThe1st]

Noone can help me? I am surprised.


-RobbieThe1st

[richk]

There is a little fuse that is involved with charging on the underside of the board. I have seen this fuse blown and the board will act as you desctibe. You need to take the board all the way out and remove the rear frame. If you sit the board in front of you upside down, with the docking station connector away from you, there is black plasiis stuck to the board to the right of the docking station connector, right under the battery connector. There is a big white fuse which controls the current from the battery. There is a smaller black fuse near there. The location is slightly different on different boards, but it has an "F" printed on the top. That is the one

[RobbieThe1st]

First off, thanks for replying.

I took my laptop apart, and found 4 fuses on the backside: two large and two small. I have marked them on the below image(large ones with red, small with blue).

I checked each of these four with my multimeter, and none appear to be blown.

Am I missing something?


Image: http://robbiethe1st.ktserv.com/images/IMG_063.jpg (488kb, 1280X960)

Thanks,


-RobbieThe1st

[richk]

I think there must be something else wrong. The 4 fuses you marked (there are many other fuses) seem to control the main and ultrabay batteries. I think the large ones control power coming from the battery and the small ones take care of the charging current coming back. I have had no luck fixing power problems that are not fuse-related. I assume your charger puts out enough current (you should have a 4.5 amp charger). I also assume that your battery is OK. (It would be best if you had another to try) As you can see, your board was already repaired at least once. IBM says the servicable used parts are as good as new, but I'm not convinced

[RobbieThe1st]

I think there must be something else wrong. The 4 fuses you marked (there are many other fuses) seem to control the main and ultrabay batteries. I think the large ones control power coming from the battery and the small ones take care of the charging current coming back. I have had no luck fixing power problems that are not fuse-related. I assume your charger puts out enough current (you should have a 4.5 amp charger). I also assume that your battery is OK. (It would be best if you had another to try) As you can see, your board was already repaired at least once. IBM says the servicable used parts are as good as new, but I'm not convinced

Hm, ok.
I am using a 4.5A charger, and infact have several around which I have tested to make absolutely. I am getting proper voltage, that is not the problem.

Battery wise, it is fine - as I said in my first post, we have another T40 laptop, and my battery will charge in the other one, and the other battery will *not* charge in mine. Aside from different amounts of runtime(my battery is much older and more used), I get the same symptoms.

Well, considering the used board worked perfectly for me for a couple of years of heavy use, and only failed when I replaced the power connector with a faulty one which fried something(as detailed in the first post), I have no complaints.

As a note, the motherboard was replaced with the one currently in it back just after I first got the laptop - It was having graphics chip problems. The new one had no such problems, it should be noted.


-RobbieThe1st