shortpin to turn a motherboard on - Page 1
Forum section: electronics / beginners

author: alps
author_rank: Contributor
timestamp: September 09, 2015, 09:03:00 pm
content: Hi everybody!I have my laptop motherboard in front of me and I'm trying to figure out how to turn it on without Power button and ribbon cable.There is a connector called JSW1 (switch) with 8 pins where to put in the ribbon cable. This connector has the following diagram:SW board and hotkey schematic diagrams are on page 125 of this service manual:http://www.datasheetarchive.com/dl/Datasheets-USER/DSAUPLD00007992.pdfI just want to short the pins on the base of this connector in order to turn my motherboard on. But which pins? Surely the second one and then?Someone has told me to solder a small wire to the second pin and connect it to the ground (areas where tightening screws in the motherboard can act like ground). But I just had a small bipolar cable (like those of stereo headphones) and so I've tried with the ground of this cable (excluding the white and red wires), without soldering anything.I've connected one end to the nearest screw slot (for the ground pole) and the other one to the second pin (being careful not to touch the first or the third pin). But all I've got is a spark and some burn on the pin. Perhaps, the ground of my audio cable wasn't suitable for this task or perhaps a solder to the pin is needed (it would be a micro-solder and I don't have any solder for this). More likely, it wasn't the right thing to do because, as far as I get to know from other people after this unsuccessful trial, the second pin must be connected with another pin, I guess the first one and, perhaps, schematic diagrams confirm my opinion.I just don't want to use a solder but find an "on-the-fly" solution to turn the motherboard on. Someone has used a flat screwdriver to short pins but I've seen on the internet that those people use the ribbon cable to do that (perhaps to avoid sparks and burn on the pins located on the base of the connector).Now, should it work if I short the first 2 pins on the base of the connector with a flat screwdriver or should I expect dangerous sparks or some possible damage to the pins (and worse to the motherboard)?Any idea about this issue?Thanks for your suggestions.

author: Cliff Matthews
author_rank: Unknown
timestamp: September 09, 2015, 09:32:20 pm
content: Something's not clear... forget the motherboard for a while. You do have the case right? So do continuity tests from the connector while tapping the switch, if you're patient, you will find your answer.Maybe someone else will download the PDF and (sorry to say it this way...) do your work for you. Flex your tech muscle - you can do itBTW, it's been a while since PCMCIA was in vogue, maybe it's seen enough action - I mean every dog has it's day - Cheers!

author: max666
author_rank: Frequent Contributor
timestamp: September 09, 2015, 10:18:01 pm
content: Alright, I'll bite.What does this look like to you?Could it be the power switch?If so, then PWRS would have to be connected to VIN. So basically short pin 1 & 2 on JSW1.Normally I would recommend using a 1k resistor for such things, because if you're wrong a 1k resistor probably won't damage anything and still trigger whatever you are trying to trigger, but in this case a screw driver seems to be the right tool for the job.

author: amyk
author_rank: Super Contributor
timestamp: September 10, 2015, 01:21:34 am
content: There's a 100k/100k voltage divider connected to PWRS already. Look at page 38 of the schematic.

author: alps
author_rank: Contributor
timestamp: September 10, 2015, 03:16:48 am
content: [Quote from: max666 on September 09, 2015, 10:18:01 pmGreat! Thanks for your suggestions!According to you, will the motherboard turn on istantly after shorting these 2 pins, I mean in a fraction of a second? And when I have to turn the motherboard off, will I have to short the same pins? I suppose so, but for a few seconds? Normally, to force the shutdown of a system a long pressure on the power button is needed. Then, I suppose that the short should last a few seconds as well. Am I wrong?

author: alps
author_rank: Contributor
timestamp: September 10, 2015, 03:34:34 am
content: Quote from: amyk on September 10, 2015, 01:21:34 amOK, but what does it mean? That I don't need to use any resistor? So a flat screw driver should be enough for this task, isn't it?

author: SL4P
author_rank: Super Contributor
timestamp: September 10, 2015, 05:56:57 am
content: My vote would go to pulling the LIDSW on, then pulsing the PWRS to turn on or off (per the BIOS settings).The lid is a slow/static event, and also interacts with putting the BIOS to seep or hibernate if the system is on. Wake if it's already asleep...The power switch also has multiple functions depending on BIOS and OS configuration.immediate, delayed etc.

author: alps
author_rank: Contributor
timestamp: September 10, 2015, 03:53:37 pm
content: Quote from: SL4P on September 10, 2015, 05:56:57 amDo you mean that it's necessary to connect across from LIDSW to PWRS in order to turn on or off the motherboard?

author: Hideki
author_rank: Frequent Contributor
timestamp: September 10, 2015, 08:55:39 pm
content: Quote from: alps on September 10, 2015, 03:53:37 pmNo, no, no! Study the schematic, page 125. The same page where you found the first image you posted. That page also shows the connection of the lid switch (upper left corner) and the power switch (right below the lid switch).Cliff Matthews asked a question that you never answered: "You do have the case right?"If you do but never measured what the buttons do... why not?We have to assume that the power switch is normally open, so when you press it, it connects VIN_10 to PWRS_10.The lid switch is not as clear, but assuming it is open when the lid is open, then closing the lid would connect LID_SW#_10 to ground. If this is the case you can probably ignore the lid switch if all you want is to turn the power on and off.