Laptop will not power on

[smschwentner]

I have a friend's Compaq Presario f755us. It will not power on. With the battery only, with battery and A/C power, and without the battery, only A/C power. The charging lights will come on, but that is it. When you push the power button, it lights up for about a second, (if that) and then that is the end of the show. The charging light comes back on.

Any ideas? She said that it was working fine but then just stopped. She also said that sometimes it will come on, but I haven't yet gotten it to. I read something about the switch with the lid that tells the computer that the lid is up, could this be something causing it? I have also read about the CPU's and stuff like that. What should I try to find out the issue? The charger is new, and it does work as I tested it with my own laptop.

Please help, as I would LOVE to get this fixed : she told me if I can fix it, I can have it!

 

[frozenlead]

You probably have some kind of short going on. I would breadboard the machine - it's the best way to solve issues like this.

 

[smschwentner]

forgive me, but what does "breadboard" mean? Take it apart and put back together?

 

[frozenlead]

Sort of. You'll want to disassemble the machine and get it down to just a board, CPU, and memory (and a heatsink). Plug it into an external monitor and keyboard, and see if she powers up. Especially for your scenario, it's preferable to get the board completely free of the chassis.

Take a pen or knife and see if you can wiggle the power jack on the machine around in it's socket. That can cause such issues.

 

[smschwentner]

hmm i dont know if I am able to do that, I am scared to mess something up. is it really hard? I mean, I am used to taking apart desktops, but not laptops. I guess it would be about the same thing...just smaller...?

 

[smschwentner]

do you know of any videos that i could watch to help me along?

 

[frozenlead]

Eh, it's not incredibly difficult. I can understand the intimidation, I had it too. Hundreds of notebook repairs later, getting them apart is a piece of cake. Taking a look at some images of yours, it looks to follow general notebook design. There's a sticky I wrote in this forum which is a general guide to notebook disassembly. If you're in my area I'd be more than happy to do it for you (PM, please). If not, I'll help with what I can.

The test on the jack, though, can be done regardless of whether or not the thing is disassembled. I'd do that anyway.

 

[smschwentner]

k well i wiggled, and nothing happened. It wasn't loose or anything. Still a no go

 

[frozenlead]

Alright. Well, if you're sure the power supply is good, why don't you try removing the hard disk and a stick of memory - maybe even the wireless card if you've access to it. Those should all be easily accessible by screwed in panels on the bottom of the notebook. I doubt they're the cause, but you never know.

On another note, does the fan spin up when it turned on? Does it spin freely if you poke it with a screwdriver? Perhaps dust has caused it to seize up.

 

[smschwentner]

nope, no noise at all from the computer. Nothing.
From what I can tell without having taken anything apart yet the fan is spinning when I poke at it.
the power supply is definitely good as it works with my laptop. Also, it is lighting up the "ring" around the power jack, and the charging light was on. It isn't now, but it has also been plugged in for at least 4 hours

 

[smschwentner]

memory removed, hdd removed, still same issue. Reinstalled, and again, same issue. I have only taken off the covers to allow access to those parts, however, I will start taking the rest of the back panel off now

 

[smschwentner]

so i found a site with detailed instructions on how to pull it all apart. Damned if I can get the screws out for the wireless card....aarrgg LOL

 

[smschwentner]

ok so I tore got into tearing it apart when i got to the end of the guide and read some comments. There were people who described the same issue they were having and started into fixes and repairs that I just do not feel comfortable doing, and also several "your MOBO is bad....". SSOO I might just ditch the laptop, save the battery and power cords (they fit my laptop) and take what's left in to a computer repair store and see what they will give me for it. Or maybe they can fix it reasonably cheap. I don't know, but I am not comfortable doing all that. It might not be worth much, but I would rather save what is saveable and not risk ruining the whole thing. Thanks for your help though!

 

[frozenlead]

If your board is indeed bad and you've got the thing apart already, you've done most of the work.

Can you see anything physically damaged on the board or chassis? Depending on model, a new motherboard can be around $60. If that's small change to you, consider it.