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Laptop turning itself off

Tekno Venus

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I've been given an old(er) laptop to either fix or strip for parts and want to see if I can repair it. It's a decent machine with a 3rd gen i7 and 8GB of RAM. Would rather not scrap it! It's a Novatech Elite N1535 - which is a custom laptop manufacturer from the UK. This should make it quite easy to get inside if I need to.

The machine powers itself off randomly, so I am assuming we have a power issue somewhere. Apparently the machine has been powering off more and more frequently, and when I picked it up it wouldn't even get to POST (it would try to spin up the HDD and switch off whilst doing that). It also wouldn't boot from battery. Reseating the HDD and RAM and booting into a Linux live USB from AC power only (battery removed), it seemed to work fine, but shut off after a 5 min stress test. I've now got it booted into Windows, and it's been sitting on a stress test for 20 mins now without an issue, but I don't trust it to keep working. I don't think it's a thermal issue, since it had issues booting from cold when I first got it.

Where would be the best place to look?

Thanks!

-Stephen
 
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writhziden

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I had a Dell system that had issues due to where the AC adapter plugged into the motherboard. Every time the plug would connect/disconnect, it slowly broke down the solder points for the power jack. That would be one place to look. If you have an intermittent connection, heat can cause bad solder connections to break or short.

If you have a multimeter, you might just start following some traces around the power sources both from the AC adapter and from the battery. See if you detect any continuity issues. If it is a continuity issue, I wish you luck in finding it. That was one of the reasons I steered away from electrical engineering.

I've been given an old(er) laptop to either fix or strip for parts and want to see if I can repair it. It's a decent machine with a 3rd gen i7 and 8GB of RAM. Would rather not scrap it! It's a NovatechElite N1535 - which is a custom laptop manufacturer from the UK. This should make it quite easy to get inside if I need to.

The machine powers itself off randomly, so I am assuming we have a power issue somewhere. Apparently the machine has been powering off more and more frequently, and when I picked it up it wouldn't even get to POST (it would try to spin up the HDD and switch off whilst doing that). It also wouldn't boot from battery. Reseating the HDD and RAM and booting into a Linux live USB from AC power only (battery removed), it seemed to work fine, but shut off after a 5 min stress test. I've now got it booted into Windows, and it's been sitting on a stress test for 20 mins now without an issue, but I don't trust it to keep working. I don't think it's a thermal issue, since it had issues booting from cold when I first got it.

Where would be the best place to look?

Thanks!

-Stephen
 

Digerati

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What makes it a "custom" laptop? And why does that make it easy to get inside? I note they do have a forum - though that does not mean it will be of any help.

Oddly, when I search on that model number, I get to a "Sorry, this product is no longer available" page on the company's site, which then dims and does not allow me to look around. :( Tried 3 different browsers.

I don't think it's a thermal issue, since it had issues booting from cold when I first got it.
It may not be a heat issue in the sense of poor cooling, but a failing device causing a partial short will cause an increase in current in a circuit which can cause near instant over heating of affected devices. Blasting a desk fan on the exposed motherboard may keep it running longer - but also risks the bad device going up in smoke. :( Got an infrared thermometer? Not exactly a conventional troubleshooting technique but these can help pinpoint hotspots if there is a short somewhere. But if the problem is an intermittent open, it won't do much good.

I agree with the course of action suggested above. I would start by verifying the output voltage of the supply while it is under load running the notebook. So with it shutting down in 5 minutes, you will have to be quick.

Unfortunately, it is not likely you will be able to find a circuit diagram/schematic so you can follow circuits with your meter. So a visual inspection may be your only recourse and if you see any solder joints that don't look right, a quick touch with a soldering pencil may repair the joint. I would start at the notebooks charger connection. Those tend to receive a lot of abuse, but sadly, not well.

I would also run it with bare minimum connected devices. If two sticks of RAM, remove 1. You can remove the drives and it should boot through POST, then halt when it cannot find a boot disk, but it should keep running. This will eliminate a bad drive pulling excessive current as the cause.

While I am not a fan of automatically replacing TIM (thermal interface materials) because contrary to what many believe, it does not need to be regularly replaced and will last 10, 15 years or longer AS LONG AS the cured bond is never broken. But since this is a used system and you may not know what the previous owner did, I would pull the processor (assuming it is socket mounted), clean the mating surfaces and apply a fresh new, thin layer of TIM. It only takes a few clock cycles to go from cool to overheated and a 3.4GHz processor (in turbo mode), that's over 3 billion clock cycles per second.
 

Tekno Venus

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Hey Bill,

By custom, I mean Novatech buy generic laptop bodies (probably Clevo or similar), and then put components inside them. When you buy one, you can choose which processor model, how much RAM, the screen resolution etc etc. They're only a small company, so use generic components they can buy off the shelf -

I had the same issue with their site :( This is the best info I could find about the model: Novatech N1535, i7-3630QM, 8GB RAM, 750GB HSSD, GT650 2GB | Dealizon

Interestingly, the laptop is currently on and has been running fine for the last 30 mins. I ran the stress test for an hour and a half and it had no problems. Yet when I got it, it shut off when trying to spin the HDD up. Only after removing the HDD, booting into BIOS (which it did first time after removing the HDD) and reinstalling the HDD would it boot into Windows.

Interestingly, despite being on for 30 minutes, the battery still shows 0%.

I'll crack open the laptop, give it a clean, and see if I can dig my multimeter out the cupboard :p

Thanks!
 

Digerati

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Do you know how long it had been sitting unused before you got it? I ask because the lubricant in some motors can pool and harden up a little when unused for a long time. Then, once they spin up and warm up, the lubricant gets evenly distributed again. Not saying that's what happened here, but it is possible.

30 minutes may not be long enough for a deeply discharged battery to "move the meter". I would give it several hours. But check the charger every so often to make sure it is not getting too warm. If very warm and still no charge indication, the battery (or charging circuit) probably has a short in it somewhere. Not good.
 

Tekno Venus

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The last event viewer entries are Oct 2016, so it's been sat around a while.

I popped it open, and cleaned out the dust (there wasn't much). Unfortunately I couldn't get the case fully open - there's a clip or screw or something I just can't find holding one corner down!

It had been running all day, no issues. Managed to re-install Windows 10 and everything. But it just shut off again. The battery is now fully charged - and was at 100% when it shut off. If it was an issue with the DC jack or something, I'd expect it to revert to battery power if it lost power from the DC jack, not just turn off completely since the battery does work now.
 

Digerati

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If it was an issue with the DC jack or something, I'd expect it to revert to battery power if it lost power from the DC jack, not just turn off completely since the battery does work now.
It depends on the exact problem. A short in the charging circuit could easily direct all power to ground since the battery is in the charging circuit too.

Fans spinning? This could be bad caps too.
 
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