Laptop turns off after exactly one minute

[chrisappleby]

I need to tap into the collective wisdom for this weird one.
I'm in the UK and have a 1 year old Packard Bell Easynote TJ68 laptop (in the USA the same laptop seems to be called a Gateway NV5) which was brought to me with a "power button problem".
It wouldn't turn on, no lights or anything, so I dismantled the power button fascia which revealed a spring and the actual power switch on a small circular circuit board. Pressing the switch powered up the laptop. So far so good.
It went though the usual Win7 bootup as far as the login screen and then it turned itself off. I pressed the power switch and it came on again but turned off just as before.
Since then I've tried the following with exactly the same symptom resulting:
- power up with PSU only and no battery
- power up using fully charged battery (the battery will charge if connected)
- hard reset holding power button in for 30 secs - 1 min with no power and no battery
- swap around memory and slots (there are 2x1GB sticks)
- boot to Linux live CD
- I started to suspect loose connections so stripped it down to the motherboard disconnecting and reconnected all leads
- despite the young age of laptop I began suspecting thermal issues so dismantled CPU/GPU heatsink, reseated CPU, cleaned off old thermal paste, re-applied thermal paste and reassembled laptop
- currently have left HDD and wifi disconnected and 1x1GB stick of memory installed and am booting from Linux CD and laptop still reboots as before
- For lack of any other inspiration, I timed the reboot cycle. IT REBOOTS AFTER EXACTLY ONE MINUTE each time! What does that mean??
- Can enter BIOS setup as normal but reboots after 1 minute
- PSU is the one supplied with laptop branded Delta Electronics Inc. Output measured as 19.49V. Seems stable even after 1 minute. However, laptop still powers off when running on battery alone.
- With all RAM out, no POST beeps, just fan noise, no screen light screen and it dies after 47 seconds. With 1x1GB RAM back in, starts booting Live CD and dies after 57 secs.
- would like to simulate what the power button is doing by bypassing it but not sure how I'd do this. Power switch is on mini circuit board to add possible complications.

Can anyone shed a little light on this?
My next theory is a possible damaged power switch circuit board/cable but before ordering one I'd appreciate your thoughts.
Thanks all

 

[chrisappleby]

Extra feedback on this issue

I just tried disconnecting the power switch lead from mobo after switching on the laptop. It still reboots after exactly one minute
Bad mobo?

 

[Xander]

I'm not the most mobo-centric guy to answer but that's where I'd lean.

I wouldlike to say that this is one of the best "help me" posts I've seen in weeks here! You've provided your hardware, OS, steps done, theories... GOOD JOB!
New guys take note: This is a really good first thread.

 

[kisk]

Mobo is bad... if you've had all the components out of the machine and it still dies after a min that's all it could be. So many components on a mobo its near impossible to figure out what exactly is the problem unless you have a few clues.

 

[loaner]

I'm not the most mobo-centric guy to answer but that's where I'd lean.

I wouldlike to say that this is one of the best "help me" posts I've seen in weeks here! You've provided your hardware, OS, steps done, theories... GOOD JOB!
New guys take note: This is a really good first thread.

+1

fillerations

....goss

 

[ATTech]

So many components on a mobo its near impossible to figure out what exactly is the problem unless you have a few clues.

Actually, it's entirely possible. You just need a working knowledge of digital circuits.