Sharpie marks on Laptop Motherboard

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thenine

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#289652 20-Sep-2021 14:42

Hi all,

I've bought a 2nd hand laptop, when i opened it up i found sharpie 'x' marks all over it. I've never seen it so I was wondering if anyone knew what the purpose of it is. My plan was to take out the motherboard and place it in an old AMD E1 version of the laptop. It's a toshiba L850 (yes I know it's old).

xpd

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#2781165 20-Sep-2021 14:52

I've seen marks before, but not to that extreme - I always just figured it was from some random QA check.

XPD / Gavin

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Oblivian

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#2781167 20-Sep-2021 14:54

Either going to be the stuffed bits.

Or the bits checked to see they aren't stuffed and marked accordingly

mentalinc

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#2781168 20-Sep-2021 14:55

Also, try not work with the insides of a PC, with socks on standing on carpet.

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xpd

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#2781176 20-Sep-2021 15:06

mentalinc:

Also, try not work with the insides of a PC, with socks on standing on carpet.

LOL, see so many pics like that selling video cards for $400+ - sitting bare on carpet.

XPD / Gavin

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thenine

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#2781180 20-Sep-2021 15:13

Oblivian:

Either going to be the stuffed bits.

Or the bits checked to see they aren't stuffed and marked accordingly

Yeah that was my thinking. Hopefully it's the latter.

mentalinc:

Also, try not work with the insides of a PC, with socks on standing on carpet.

Hahahaha, I knew someone would say that. I ran out of room on my work station so I put it on the floor to take the photo. But I will not stop working in my socks😅.

1101

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#2782072 22-Sep-2021 11:46

socks & carpet = real word :-)

I bet most of those making those sort of comments.....
dont ( with a few exceptions) have a dedicated properly setup Anti Static workstation
And I bet they wear clothes made of synthetic fibres . And sit on a chair seat made of synthetic fibres .

The assembled boards arnt that susceptible , generally.
SOME bare parts are , but we arnt removing or installing chips . Just moving a assembled board .

Theres a few Youtube vids where they try & see what it actually takes to damage assembled board with static .
If it was such a big issue, Techs would never be able to do any onsite repairs or upgrades, ever .

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thenine

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#2782107 22-Sep-2021 12:27

1101:

socks & carpet = real word :-)

I bet most of those making those sort of comments.....
dont ( with a few exceptions) have a dedicated properly setup Anti Static workstation
And I bet they wear clothes made of synthetic fibres . And sit on a chair seat made of synthetic fibres .

The assembled boards arnt that susceptible , generally.
SOME bare parts are , but we arnt removing or installing chips . Just moving a assembled board .

Theres a few Youtube vids where they try & see what it actually takes to damage assembled board with static .
If it was such a big issue, Techs would never be able to do any onsite repairs or upgrades, ever .

Yeah I get best practice and all of that, but I've put some boards in some not ideal conditions and never had issues. There's a few channels where they've tried to fry PC components and it takes a lot more than you'd expect.

Anywho, threw the board in and it worked. So thanks all for your help. I can continue playing in my socks with the confidence that the parts will not melt through the floor (touch wood......and a PCB).

fe31nz

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#2782391 23-Sep-2021 01:10

I have not watched any of the YouTube videos about trying to cause static damage, but having worked in the electronics manufacturing industry for some time at the start of my career, the first thing that comes to mind when people are trying "to fry PC components" is that static damage is rarely immediately obvious - you are unlikely to see damage that will make something just stop working (although that can happen). Usually, the damage is cumulative and subtle. For example, I had one old CPU (a 6802 I think), where all the short instructions worked fine but long instructions (such as ones using an index register) frequently failed. The software I was trying to run on that CPU was mostly short instructions, so it was quite a while before I caught on that it was damaged. Translate that into a modern CPU where a small bit of the die takes damage, and all that is affected is one of the vector type instructions that are only used in certain specific types of software. So the PC that has that CPU installed may only ever be running software that never uses the affected instruction, until it gets passed on to a new user who has a different job. Then they suddenly find that the software they use that uses lots of vector instructions is doing strange things, but only sometimes.

That sort of problem is serious as it uses up lots of time and effort trying to track down what the problem is. It is much better to avoid problems like that by using proper anti-static precautions whenever possible, and it is generally much cheaper to do that than to deal with the problems that get created by static damage. There is a general principle of making things that applies equally to manufacturing and writing software. Preventing a problem has cost 1. Fixing a problem before it leaves the designer/developer's hands has much higher cost, say 5. Fixing a problem that gets into an end product and is discovered by end of production line testing is more expensive again, say cost 10-20. If the problem gets to a customer, the cost is really bad, typically 100 or more. And it can break your company if it happens too often.

Do remember that there are two types of static damage that happens - the most obvious one is where there is a static discharge that causes damage. The discharge does not have to be big enough to be seen or felt, and usually is not. But the second type of damage is caused by potential differences, where something with a high static voltage on it comes near to a vulnerable piece of hardware. Then there can be big voltage applied to bits of silicon, but virtually no current. This can cause very subtle damage as ions migrate around junctions and similar effects, and can take a long time to show up. So you may have mishandled a hard drive when you installed it, and it fails after 8 years of use when it would, without that damage, have kept on going for 10 or more years.

In the home environment, you do not actually need to have industrial level anti-static gear. It does help to have and use a wrist strap, as that makes it easier to work on a PC. Wrist straps are pretty cheap and easy to get. For example:

https://www.pbtech.co.nz/product/SEVOEM0064/OEM-Posh-Anti-Static-Wrist-Strap-Blue

Having an anti-static mat is not really necessary, especially as most people do not know how to use one properly. I actually do not have one - I use our stainless steel kitchen bench as all metal benches are required by law to be earthed (and I checked ours was). To work on a PC without a mat you need to keep the PC power supply plugged into the mains, but the mains switched off. The power supply's metal case is in contact with the PC case and earths it. Then when you are taking things out of anti-static bags, or out of the PC, you first touch the PC case to earth yourself, or preferably connect your wrist strap to the case. Things that are not in bags should be put down only on the earthed PC chassis or on top on an anti-static bag. It does pay to check with a meter that the chassis earth is present, and locate a good spot to connect your wrist strap. All that is not very difficult to do and avoids a very large part of the static damage problems.