Naked Science Forum

Non Life Sciences => Geek Speak => Topic started by: Geezer on 11/05/2011 16:52:02

Title: Why does the power button on my laptop not work?
Post by: Geezer on 11/05/2011 16:52:02
The power button on my HP Pavillion is kaput! It seems to have no effect at all. The LED that illuminates the button when power is on is also not working. Fortunately, I can power the machine up by pressing one of the "Quick Play" media buttons, then navigate from there back to Windoze.

I actually took the thing apart and tested the switch. There is nothing wrong with it, and all the cables associated with it seem to be properly connected. I supect something on the motherboard is banjaxed.

Has anyone had a similar experience?
Title: Why does the power button on my laptop not work?
Post by: RD on 11/05/2011 18:45:08
May be a clue in the Windoze "event viewer" logged at the time you attempted to start up (or shut down).

dodgy battery ? ... http://bpr.hpordercenter.com/hbpr/ 

Title: Why does the power button on my laptop not work?
Post by: SeanB on 11/05/2011 20:57:25
Eiuther the cable is damaged, or it is not inserted correctly at one end or the other. This is more likely, given that the LED next to it is not on. That is normally powered by the computer, and would at least flash until the bios finished a self test. Release the cable both ends, and reconnect, remembering to clip the connector latch in correctly.
Title: Why does the power button on my laptop not work?
Post by: Geezer on 11/05/2011 21:26:40
Eiuther the cable is damaged, or it is not inserted correctly at one end or the other. This is more likely, given that the LED next to it is not on. That is normally powered by the computer, and would at least flash until the bios finished a self test. Release the cable both ends, and reconnect, remembering to clip the connector latch in correctly.

Thanks Sean. I tried that, to no avail. I suspect some component has failed. The failure mode was somewhat progressive over time as if some semiconductor was gradually going south. What's slightly odd though is that the forced shutdown does not work either, and I think that goes straight to hardware. This laptop also has an infrared remote control which I never had much use for. It also has a power on/off function, but the remote does not seem to work at all (the battery in it is fine).

As the laptop is more than five years old now, I'll probably just live with the issue until something else fails, then junk it! I seem to have an "extra" screw now too  [:D]. Obviously I left it out when I put the laptop back together, but I can't find where it goes - oh well.

Title: Why does the power button on my laptop not work?
Post by: syhprum on 12/05/2011 20:39:11
It is embarrassing to have a screw over!, unless you are familiar with dismantling a particular unit it is best to keep some written notes from whence you take screws.
Title: Why does the power button on my laptop not work?
Post by: Geezer on 12/05/2011 21:29:17
It's an extremely small screw. Obviously, it can't be very important  [;D]
Title: Why does the power button on my laptop not work?
Post by: CliffordK on 12/05/2011 22:33:44
Odd that you are able to find an alternative way to power it up.
Sometimes I have to remove the battery on my laptop for it to power up properly.  But, it sounds like the button is bad.

I've repaired mouse buttons before.

The button you see on the keyboard often has a switch underneath it.

You might be able to replace the switch.  But that would mean finding a replacement and soldering it in.  Some laptops may have a separate power bar that could be purchased on E-Bay for $10 or so.

However, sometimes the switches can be carefully disassembled, in which case you may find a cover and a small metal disk inside the switch (or rubber/carbon disk).  A speck of dust under the disk and the switch will fail.  Clean everything up.  Reassemble.  And cross your fingers.

Title: Why does the power button on my laptop not work?
Post by: Geezer on 12/05/2011 23:36:42
Thanks Clifford. I tested the the switch under the button and it's ok. It's mounted on a little PCB along with a LED. The LED does not work either. I suspect a driver chip on the motherboard has died.
Title: Why does the power button on my laptop not work?
Post by: CliffordK on 13/05/2011 00:37:23
That little board should be easy enough to replace, and generally not too expensive on E-Bay, especially on an aging laptop.

HP did have some power issues on their laptops, perhaps 5 or 6 years ago which I think did necessitate a motherboard swap.  I'm thinking back that I had gotten one of the bad HPs, and perhaps I should have tried pushing more buttons in it  :P
Title: Why does the power button on my laptop not work?
Post by: Geezer on 13/05/2011 00:55:40
Alas, the only components on the lttle board are the power momentary switch, and a LED. The switch works just fine, and I'm willing to bet the LED is OK too.
Title: Why does the power button on my laptop not work?
Post by: peppercorn on 13/05/2011 10:46:59
Dry joint?
Title: Why does the power button on my laptop not work?
Post by: Geezer on 13/05/2011 17:08:13
Dry joint?

Maybe, but the failure was more gradual deterioration than intermittent. It could also be tin whiskers, in which case I'll never find it!
Title: Why does the power button on my laptop not work?
Post by: peppercorn on 14/05/2011 13:36:19
I had a think with a Dell Inspiron where to get it to switch on I had to press down on the case as I pressed the On button. Over time the amount of pressure I had to exert became greater and greater until one day it simply wouldn't turn on at all.
....
That's when I got mad! [>:(] ... and my girlfriend at the time looked like this [::)]

[:D]