Thread: ciruitry and solder help for ibm laptop lid switch

Originally Posted by hooraysimpsons

Hello,
I am trying to use the lid switch on my ibm r40e thinkpad laptop to automaticlly put the laptop into standby and bring it out of standby. I want to hook it up so that when power is supplied (the car is on) then the laptop thinks the lid is open and when power is not available the laptop thinks the lid is closed.

I have a multimeter but there are six leads into the switch on the mobo as far as I can tell so I was wondering if anyone could help me figure out what to measure? Here are a couple links to some pictures of the switch. I apologize for their quality.


http://students.engr.ncsu.edu/ans/pics/im1 good view of all six leads
http://students.engr.ncsu.edu/ans/pics/im2 better focus but can't see all the leads

Once I have measured what is needed then I will also need some help determined what circuitry I need to make it work. Also if there is a kind of solder that I should be using for this. Right now I have Rosin-core solder.

Thanks a lot,
Paul

There is no standard for any switch. The fact that there are 6 leads doesn't really tell us much. You will need to test all the wires against each other with the "continuity" setting of you Multimeter to determine which contacts are "close" or connected when the button is pressed.

Then, just solder wires to those contacts (you will probably only need 2 wires on two contacts) and bring them out to a relay that you can control with the ignition or with another switch.

Now, are you sure that the screen switch will put the laptop into standby or hibernate and take it out when it is open??

Michael

Originally Posted by hooraysimpsons

ok so I did a continuity check on the leads (on the multimeter its the symbol in the resistance range that is a line with an arrow and a line prepedicular across the line). Updated the im1 link with numbers which may not be needed.

The results:
1,2,3,4 seem to always be connected/closed circuit. 5,6 seem to always be connected. And then when the switch is depressed all of them become closed circuits.

What do I need to purchase ciruitry wise? I am a complete newb as far as circuits and relays and eveything goes.

The leads are really small what is the best soldering technique... never really soldered anything important/small?

Thanks a lot

Simple. Read up on relays here http://www.the12volt.com/relays/relays.asp

Then, get a relay, and wire it accordingly.

As for soldering. The best advice is, practice on something else first. If you have an extra/broken PCI card, or something with some resisters, caps, whatever on them, and practice soldering. Get a low wattage iron, maybe 15 or 20 watts (an adjustable one is fine if you might have need for hgh wattage in the future) and get the SMALLEST soldering iron tip you can find, and thin solder.

For the button, find some thing wires, something like 22 or 24 (even from an old telephone cord will work) and solder the wires to the pins easiest to get to. Make sure that you use a strain relief on the wires by attaching the wires to something sturdy several inches away from the solder connection (often times called a "solder joint") so that you don't accidentally rip the wires off the board, lifting any traces, ruining the button, the board, or even just your soldering job.

I would also check out this link for some help. http://www.google.com/search?hl=en&q...older+properly

Good luck
Michael

This seems like a more difficult route than what I (and most people) do.

Why not just solder to the power switch and set windows to standby or better yet hibernate when the power button is pressed.

Putting the laptop into standby means the laptop will have to be on all the time and will drain some power.

Also, I would invest in a basic startup/shutdown controller like the one from the mp3car store and save yourself alot of problems trying to figure all of that out. For under 50 bucks you can hook it up to take care of everything your wanting to do and never have to worry about having a dead battery during a worse case senario.