Gateway nv77h08u power button board (experts only!)

[sdpctek]

I'm working on a Gateway NV77h08u. The only way I can get it to power-on is by bridging the pins on the motherboard that the power button ribbon cable plug into. If I do this, the laptop will run fine for as long as it's on, even the battery charges.

Clearly that meant it needed a new power button assembly/power board/ribbon cable so I ordered a replacement (see pictures below) however I just installed the replacement and it also does NOT work. I noticed, too, that a part of the power button board gets REALLY hot when the AC adapter is plugged in (too hot to touch even). This suggests some kind of circuitry issue does it not? Here's a picture of the part and the replacement side by side with the part that heats up circled in red:

direct link if picture doesn't show up...

https://drive.google.com/file/d/0B1AlnnzXuizmY2pSY0hrdEhUWEk/view?usp=sharing

I'm about 2 minutes away from just soldering 2 wires to the pins and running them outside the case as a means for turning the thing on but thought I'd ask the experts here on Toms for any ideas. I've been in IT for close to 15 years but I learn new stuff all the time from good techs. =)

Thanks in advance for any replies.

 

[C12Friedman]

How confident are you of the power adapter putting out it's stated voltage?
I wish I had some reference to that motherboard (notably near the power connection - a top and bottom picture would be awesome) . I think soldering a jumper in wouldn't be too beneficial overall since it appears there is some kind of overcurrent event going on there - a burnt rectifier or diode or... You could sacrifice your knuckles in an attempt to find the source after powering the unit up or there may even be visual clues near the connection (discolored IC's, burnt or blown IC's, smoke rising from a specific part of the motherboard...)
I would personally be looking over the circuitry around that area real good.

 

[sdpctek]

Hi, thanks for the reply.

I'm using a universal "iGO" laptop adapter but it HAS been tested with a genuine Gateway adapter with the same results. In fact, almost every component (besides the motherboard) has been swapped out with a 'known working' one with the same results.

The last thing I need around here is another laptop in pieces so just to get it out of the way, I went ahead and soldered wires from an old IDE cable to each of the pins, taped them down and routed them outside the case next to the VGA port. Doesn't look all that bad and touching the wires to one another starts the laptop every time.

https://docs.google.com/a/mobilecomputerwizard.com/file/d/0B1AlnnzXuizmcUV6cy1UZlFaNzg

https://docs.google.com/a/mobilecomputerwizard.com/file/d/0B1AlnnzXuizmN1lETjRDN0NlYlE/

It probably wouldn't be all that hard to just run my 2 wires to the back of the actual power button and rig it so that the wires touch when the button is pressed down, thereby powering-on the laptop. What other function does the power board even have anyhow? I didn't even put the power button board back inside the laptop and it works fine as far as I can tell, just no LED on the actual button.

Anyways, I think you must be right about an over voltage. Probably a burnt resistor or something somewhere. I will take a closer look at the components around that area, keeping your suggestions in mind, as well as do a thorough test/trace of the power circuit from plug to battery terminals (if I can find schematics). I certainly would've noticed smoke coming from the board but I'm no electrician and have only basic knowledge of how to test IC's beyond basic voltage and continuity.

Thanks again for the reply! =)