Laptop shutting down randomly

[200820]

I have an Acer laptop that has started to turn itself off after roughly 15secs, although this time decreases to as little as 5secs if you keep trying to turn it on a few times in a row.

On the first attempt of trying to start it it gets by the acer screen and then shows a 'Windows was not able to start properly. A recent Hardware or Software change may have caused this' screen, the laptop then just shuts down without any errors or warning.

I was thinking that maybe it was overheating (especially because of the more u try to turn it on the less it stays on for situation) but I took the cover off the back and the fan is coming on fine and only turns off when the laptop does.

This also happens when it is plugged in at the mains so I'm assuming it's getting enough power.

Any ideas??

 

[cdogg]

Try taking the battery out while leaving it connected to the power cord. If this works, then the battery might need replaced. Also go into the BIOS when you get a chance. If the laptop still turns off while you're staring at the screen, then it has nothing to do with the hard drive.

Other than that, there's not much else you can troubleshoot aside from trying a replacement AC adapter or reseating the memory. If none of that helps, then you probably have a dying motherboard.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Einstein
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[200820]

I've been in the BIOS and it still turns off even when in it & I've also already tried reseating the memory.

I'll give the battery and replacement AC adaptor ideas a go later on when I get home.

Thanks for the reply cdogg

 

[rclarke250]

Just because the fan is spinning doesn't mean it isn't overheating. The radiator fins can be clogged with dirt, fan spins, but can't really exhaust the hot are to well. Also it is common for laptop makers to not put very good,or any, (hp ) thermal paste on the CPU.

It is worth a try to at least check this out. Also, just because the fan spins doesn't mean the system can see the fan pulses from a bad rpm sensor on the fan, and this would cause the system to shut off also, as most laptops use a thermal sensor in conjunction with the fan rpm sensor.

 

[200820]

When I had the cover off I couldn't see too much dirt around the fins but I suppose I could give it a quick clean anyway to see if it helps.

Would the only way to check for a bad rpm sensor be to replace the fan?

 

[rclarke250]

the dirt won't be on the fins of the fan, it will be on the fan side of the radiator fins. You can check the rpm sensor several ways, if you have the tools. O-scope would be best. A frequency tester, or true rms meter if it is fast enough. I have never tried it, but I would think that if you only have a VRM you can set to voltage and see if you get any reading at all, I would think the pulses would be so fast as to look like a straight voltage to a cheaper meter. If I get the time today, i'll experiment with it. usually I just swap out another fan,it's faster than setting up the oscope.

 

[stduc]

Try removing the battery and external power and holding the power button for about a minute. Then replace the battery and main power and see if that has reset everything so it boots. 2 chances! it works or it doesn't. But sounds like the CPU is unhappy to me. Possibly thinks its overheating.

[navy]When I married "Miss Right" I didn't realise her first name was 'always'. LOL[/navy]

 

[rclarke250]

rpm sensor for the fan can be tested with a regular volt meter, it's not accurate but it will tell you if it has some output.

With a volt meter set to dc, typically the rpm sensor of the fan will have a yellow or blue wire. set the ground lead on a ground point on the laptop system board, and the positive on the rpm output. You should see about 2.5v or half of the 5v input. As it is a square wave output, and swings from 5v to ground, you should read half of the input voltage.

 

[cdogg]

I'm not disputing the value of knowing how to test a fan's RPM, but I also can't tell you the last time I had a laptop power off due to a faulty fan. If a laptop has been left off for a few hours and is at room temperature, it shouldn't overheat in under a minute (let alone 5 minutes in most cases). There could be a short somewhere, but I don't think it's a heat issue at this point.

In this situation if it's not the battery or AC adapter, then it's the mobo or CPU. It's pretty rare if it's the CPU, which is why I would hold off swapping that component until last.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Einstein
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[rclarke250]

Actually, I've seen laptops, shutdown very fast because it didn't see the fan, granted, I got a message saying that there was a fan fault, and then power off.

I didn't actually say that I thought it was overheating. I said, just because the fan was spinning, doesn't mean that it isn't overheating.

I agree, that a lot of newer cpu's are very heat efficient, and some can actually run with passive cooling given enough room to dispense the heat with a big enough heat sink.

And laptops can have some very strange problems crop up, I was working on an HP today, that if a dimm was in slot 2, the video would shut off. Tried new memory and no go, but if I put any of the dimms I had in slot 1 it would boot, in slot 2, no video. Not even external video.

I'm just saying that it is a good idea to be thorough. And I agree it most likely is a system board issue, but it never hurts to check out everything.

 

[cdogg]

Sure, there's nothing wrong with checking out everything. It boils down to the level of expertise the technician has and how much time spent is worth finding a fix. Unless you work in a shop that has a lot of spare parts from similar models, chances are you're not going to have that spare fan to try, or you'll be hesitant to make expensive purchases. For example, you probably wouldn't go as far as buying the motherboard unless the laptop was less than 2-3 years old. You also wouldn't invest in a voltmeter or oscilloscope if working on laptops is a rare occasion for you.

Start simple with components that have the highest chance of being the cause, working your way up as far as your wallet is willing to take you.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Einstein
[tab][navy]For posting policies, click [/navy]here.

 

[200820]

Appreciate all the replies and ideas, thanks a lot!

I tried taking the battery out and booting with the power cable in but had no joy there either, just the same results.

I think cdogg has hit the nail on the head though with regards to having the spare parts as unfortunately I don't have a spare fan that I could try and wouldn't be willing to splash out on a new motherboard as the laptop is roughly 2-3 years old anyway.

If I ever get this sorted I'll put up a post and let you guys know, thanks again!

 

[goombawaho]

Why don't you see if you can take it apart enough (open it up) and then direct the output of a lawn blower (on low speed) to keep the guts cool while you fire it up.

That would be enough to discount heat/fan.

 

[stduc]

If my earlier suggestion didn't work (You haven't said) then I agree. You have nothing to lose by trying to get inside and see if anything is obviously amiss. Re-seat any cables you can. Clean the heat-sink and fan (A vacuum cleaner with a soft brush attachment will do the job, but jam the fan with something non-metallic, a toothpick works for me. If you let the fan spin due to the vacuum then it can generate enough volts to screw up the mobo. Re-assemble and cross your fingers. Best of luck.

If that fails then as you say, an Acer, 2-3 years old is probably not worth fixing. Next time, for laptops anyway, the extended warranty can be worth a look, but read the small print carefully.

[navy]When I married "Miss Right" I didn't realise her first name was 'always'. LOL[/navy]

 

[200820]

To be honest I think it is more likely that it's turning off due to the cpu not receiving the pulses from the fan to tell it that it's on rather than the actual amount of heat as the machine turns off very quickly and little heat builds up in this time.

I haven't got the laptop with me in order to try your previous idea stduc but can I ask why you think this might work??

I've already had the case off and gave it a quick clean (very little dust etc anyway), reseated the RAM and any cables I could get my hands on.

 

[cdogg]

stduc's suggestion is based on a common method used to troubleshoot older laptops particularly from HP and Dell. The idea behind it is that you are draining the capacitors on the motherbosrd that still might be holding a charge when you remove the battery and power cord. This helps to perform a full cold reset before attempting to turn it back on.

There have been a number of times in the past (more than 4-5 years ago) where this suggestion has worked for me. On newer systems, I don't believe this is still as much of an issue but it's worth a shot.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Einstein
[tab][navy]For posting policies, click [/navy]here.

 

[stduc]

To be honest I can't remember how or when I learned that trick - but on occasion it works. I have always imagined it cleared something out of somewhere. Worth a go though I would have thought.

[navy]When I married "Miss Right" I didn't realise her first name was 'always'. LOL[/navy]

 

[G0AOZ]

If you're taking it apart, see if you can clear CMOS by removing the 3v battery. An Acer laptop I bought very cheaply for spares, wouldn't boot and just produced random characters on the screen. I had to unsolder the battery from the motherboard as there was no jumper, and then resolder it back. This appeared to solve the issue. Might be worth a shot with yours. However, it all depends upon how much time and energy you want to invest in it. Debatable if it's commercially viable though...

ROGER - G0AOZ.