Doubts about: working laptop without a soldered ram/vga/battery

[DoOm86]

I'm new to elettronic, so perhaps my question has no sense.
Can a laptop still work without one of the soldered ram?
I was wondering if a laptop (or any other device actually) can still works if removing a faulty soldered ram without soldering back a good replacement. Of course considering the mainboard has other ram chip perfectly functional.
I tried on a MacBook Air and also an Asus laptop and it seems no possible without a replacement. At least, not just removing the faulty one.
Sometimes for the seek of data recovery on a flash soldered drive on the mainboard, could be a useful thing to not look for a ram replacement which sometimes it can't be found.

What about without a dedicated but soldered vga (if not in the same bga of the cpu)? If the cpu has integrated vga also, desoldering the dedicated vga would not make the laptop works. But is there a way?

And there are cases where without the lithium battery connected a laptop can't work at all even if plugged in with its original charger?
For example, I read that few laptops have a new hybrid charging topology circuit which can work with a supplement battery+charger mode to provide additional power.

Thanks to everyone.

[piernov]

Re: Doubts about: working laptop without a soldered ram/vga/battery

Can a laptop still work without one of the soldered ram?

No, only if the entire rank is disabled (which is not always possible) and there is another working one (soldered or on a SODIMM module). Reason is that memory bus is always 64-bit on a given channel and several ICs of 4, 8, or 16 bits are used to make 64 bits so you can't remove one 16-bit IC and get a bus width of like 48 bits. (sometimes there can be only one IC of 64 bits but it's not that common)

What about without a dedicated but soldered vga (if not in the same bga of the cpu)? If the cpu has integrated vga also, desoldering the dedicated vga would not make the laptop works. But is there a way?

That's generally called "dis-to-UMA conversion".

And there are cases where without the lithium battery connected a laptop can't work at all even if plugged in with its original charger?

Yes but very rare, mainly some ARM laptops or very low-end Atom laptops that are more alike to a tablet.
But some other laptops require a battery to work properly. (MacBooks for example)

[RethoricalCheese]

Re: Doubts about: working laptop without a soldered ram/vga/battery

Workstations also might require a working battery to turn on. ZBook comes in mind.

There's a workaround tho.

And some models might require a working battery to boot into OS. Like T480s.. Sometimes..

[DoOm86]

Re: Doubts about: working laptop without a soldered ram/vga/battery

No, only if the entire rank is disabled (which is not always possible) and there is another working one (soldered or on a SODIMM module). Reason is that memory bus is always 64-bit on a given channel and several ICs of 4, 8, or 16 bits are used to make 64 bits so you can't remove one 16-bit IC and get a bus width of like 48 bits. (sometimes there can be only one IC of 64 bits but it's not that common)


That's generally called "dis-to-UMA conversion".


Yes but very rare, mainly some ARM laptops or very low-end Atom laptops that are more alike to a tablet.
But some other laptops require a battery to work properly. (MacBooks for example)

First of all, thank you for the reply. I wasn't sure to get one.

RAM related:
Your explenation makes perfect sense and it helps me a lot to understand better the topic. If i find a corrupted RAM then, most of the time i'll have to look for a replacement. I guess, like it is for the Graphic Cards, i can just replace the defected one and not necessarily the whole rank, right? I just got a Macbook Air in my lab with a dead RAM chip (16 total) and it's the perfcet occasion to learn more about this matter.
VGA related:
this "dis-to-UMA conversion" is something completely new for me and i'll study it, thanks.
BATTERY related:
As i imagined, since i have never encounter a similar circuit on a laptop, but i read somewhere it was starting to be a bit more frequent nowdays on very base laptops or very high demanding power laptops.
Unfortunally i did not check this in recent apple macbook, in old ones yes and they were working just fine without it, of course with all the cons on not having a battery connected.

[DoOm86]

Re: Doubts about: working laptop without a soldered ram/vga/battery

Workstations also might require a working battery to turn on. ZBook comes in mind.

There's a workaround tho.

And some models might require a working battery to boot into OS. Like T480s.. Sometimes..

Thanks for your reply.
There is always a workaround, it's the beauty of electronics as i am starting to understand since i'm not an expert
That's interisting, looking forward to put my hands on one and try to learn something new.

[piernov]

Re: Doubts about: working laptop without a soldered ram/vga/battery

I guess, like it is for the Graphic Cards, i can just replace the defected one and not necessarily the whole rank, right?

If you are able to figure out which IC is bad, yes.
If the failure is a partial or full short to ground, very often several (or all) ICs are a damaged.

I just got a Macbook Air in my lab with a dead RAM chip (16 total) and it's the perfcet occasion to learn more about this matter.

Note that if it is an 820-3023 board (2011 13"), replacing RAM ICs won't fix it permanently, it may come back to life for a short while but will fail again.

[DoOm86]

Re: Doubts about: working laptop without a soldered ram/vga/battery

I wanted to thank you again for the informations you provided.
I successfully changed the faulty chip ram and now the Mac air is working well (it has been a week or so). It was a Mac air 2010. I informed my client about the risk of having the same issue again regardless what you mention about a similar but not smae motherboard, but he accepted the job anyway.

I also studied about the "dis to Uma" and so far it's out of my league to be honest, since the only way to do it is to study the schematic and find a way to do it. My knowledge in electronics is not that good yet even though I can read schematic, I can't play with it.
If someone has general documentation about it (whatever it is) and the willing to share it, I would like to study it.
What I found so far online are information about specific cases and not about general knowledge to learn how it really works or have more info about it.