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highlawnFlag for United Kingdom of Great Britain and Northern Ireland

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Power/Boot problems on Acer Aspire 5735

I'm currently using an Acer Aspire 5735 laptop, and am experiencing some power/boot problems to it.

If I plug a power adaptor in, the machine turns on automatically (it should wait until I turn the machine on) and for a battery it works as normal. If I power on, the machine starts (Motherboard LEDs come on) and the fan starts to spin up, and after about 10-15 seconds it shuts off again. If it's plugged in, a few seconds later it will start this process again.

I've tried it with just power, just battery and using both and each time it gives the same results. I've opened it up and removed components one by one, til I'm just left with the motherboard on its own and judging by the LEDs it's doing the same thing as before - powering up then shutting off a short time later.

Through process of elimination, it's got to be a problem with either the motherboard or the PSU, surely? I'm fairly confident it's not the plug itself, since it behaves exactly the same with the battery. Looking over the motherboard I can't find any signs of obvious damage (none of the cylindrical things on the motherboard are bulging or burst like one site recommended to look out for).

Is there any way to find out where this problem is coming from?
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ekincam

Do you have it set in the BIOS to turn on automatically when power is applied?

Although the behavior makes me suspect that something else is broken here since it turns itself off after a few seconds.
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ASKER

I've never set it in the BIOS to do so, and previously it didn't, it's only now that it's started to do so. I'm happy for it to boot automatically with the power, as long as it can stay on once it's done so!
Avatar of Grant1842
I have to ask .
Have you tested a known good stick of memory ?

Also put some new thermal paste( artic silver) on the CPU and GPU .

It acts like an overheating issue.

I have to ask all so have you blowed out the heat sink from the inside out usually there is lint build up there blocking the vent ?
I removed the heatsink and removed all the dust and lint that was there, this didn't seem to have any improvement - the fan starts to spin up, then stops shortly before the power cuts out. The thermal paste on it still looks intact, should I put some more on anyway?

I'm not sure what you mean by testing a good stick of memory?
It all so could be a bad capacitor on the motherboard.
If you can get access to and ESR meter you could test to see if the caps are good or bad . They can easily be bad and not bulged up like in your post.

There are lots of surface mounted caps to not just the round electrolytic ones that you can see bulged up.

That is why you need an ESR meter to test the Equivalent Series Resistance to find the bad cap. A good ESR meter will check the Compedence as well.
Ohh a good stick of memory....
A stick of memory that you have tested it a differnt laptop and works with no problems in that system.
Something like this could be an Optoisolator .
Optoisolators are used as feed back circuits.  They take a voltage on one side of teh component and project light to the other side usually where a transistor is used to turn things on and off from there.  But this will involve live voltage testing and , at this stage in the game it would be better to have a Service manual to see what voltages are expected where.
You may be able to take out the battery from the mother board to clear the CMOS of the BIOS . Sometimes the cmos gets corrupted and clearing it helps these problems.
try this :
remove battery and AC adapter
hold power button for 20 sec
insert battery and AC and test ..
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