Thinkpads Forum

First of all I want to say that I have been using this forum for some time now,and for the first time I coud not find what I am seeking.

The Question is if anyone her can tell me what is the purepouse of the big white tree leged "thing" on the left side of the circuitboard

http://www3.sympatico.ca/milnoc/TP600Ba ... nside.html

To me it seems to control the negative side of the battery.

The three-legged component you are talking about does not appear to be connected to the negative (ground) side of the battery. For your reference, I am using the picture titled "The circuit board" (third one down from the top) at the site you posted for my following descriptions. I have also given each terminal of that device a number so you know what I am measuring. The terminal that is by itself toward the "bottom" of that picture is 1. The terminal that is located directly above 1, on the opposite side of the device is 2. The terminal that is to the left of 2 is 3. For a crude picture:

....3....2
..........1

I have measured 0 ohms from the battery's negative terminal to the solder point closest to that component. That point is labelled "PG" on the circuit board. Looking at where the circuit traces are going on the top of the board, I'm pretty sure that's ground.

I read open circuit (infinity) from the battery's negative terminal to all three terminals of that part (1, 2 and 3).

I read 0 ohms across terminals 1 and 2.

I read about 32.3 ohms across terminals 2 and 3.

I also read the same 32.3 ohms across terminals 1 and 3 (which stands to reason since 1->2 is 0 ohms).

Reversing the multimeter's leads does not make any difference in the resistance readings (i.e. no 'diode' effect).

In short, I have absolutely no idea what this could be.

Thanks for the quick reply I measured open circuit 1-2 on my card and I also have no negativ on the pin for the conector .

Can this ting be a fuse?

kjell wrote:I also have no negativ on the pin for the conector .

I'm not sure what you are referring to here.

kjell wrote:Can this ting be a fuse?

I suppose it could be some sort of electronic fuse (for lack of a better term), although I am not familiar if such a device exists. To me most three-legged devices fail under the category of transistor, SCR, TRIAC, etc. Seeing how our two resistance readings are different across terminals 1 and 2, can you tell me what the condition of your battery was before you took it apart? Mine was "dead". It would not accept any charge and actually had a slightly negative voltage at the battery terminals.

I am ref. to the pinconnection for the computer.

I do agree with you that this a peculier thing,but now I have desolder it and it say on the backside:F74 B4 400UMI 133degr.C

Ah, thermal fuse perhaps?

(edit: Hmm... maybe not... all the references I have found are two terminal devices)

Still mine shows open circuit and yours closed that means that mine is broken,I just put in new battery-cells and read apr.11,7v
internal but nothing out on the connectors to the computer.
I think I need a new card or this "thing"

kjell wrote:Still mine shows open circuit and yours closed that means that mine is broken,I just put in new battery-cells and read apr.11,7v
internal but nothing out on the connectors to the computer.
I think I need a new card or this "thing"

How do you connect the new cells? They seem to be soldered using some kind of electrical welding.

Just need cells with solderig-tag,you can buy them with or without this tag same cost.

To me most three-legged devices fail under the category of transistor, SCR, TRIAC, etc. Seeing how our two resistance readings are different across terminals 1 and 2, can you tell me what the condition of your battery was before you took it apart? Mine was "dead". It would not accept any charge and actually had a slightly negative voltage at the battery terminals.

The cells were dead reading 0,0v on all of them

I really have no idea, but from the size, it appears to be a power handling device. My first guess is that it's part of the charger circuitry, probably doing the job of a pass transistor in the charger/regulator circuit. I would not think that a (series) device such as a transistor would be used for battery output, as any forward resistance would be dropped as heat--a waste of power on a battery circuit


I've got a dead 600 battery around here, if I get time, I'll find it and do a little probing.

Did you try resetting the cells?
There is a small hole on the + end, poke a paperclip in there and there is a "reset button" in there. It pops when the cell voltage gets too low.

carbon_unit wrote:Did you try resetting the cells?

Using the link that was posted by kjell at the start of this thread, can you indicate exactly where the hole you are talking about is?

To Carbon:
This is new cells they all have around 3,8volt so they could not need resetting.

The holes are in the topp of battery(positve side) you find it in the same plass as you found the picture

I now found out that the white tree leged "thing" is a sort of fuse,but now I have an other problem and that is how to reset the electronic card.
Anyone that know what to do?