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  Using a power supply a bit bigger then the original? (Laptop power) 
 
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Michael Schiele Oct 13, 2010, 11:42am EDT Reply - Quote - Report Abuse
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Hey guys. recently i was given a Sony Vaio VGN-SZ750N that was "bad". turns out, the power supply was shot. easy fix! i ordered a new VGN-AC19V19 off eBay for $14 total. when i received my power supply it was a VGN-AC19V10 instead.

Specs:

AC19V19 (Original)
Input: 100-240V ~ 1.3A(1.3A)
Output: 19.5V(19.5V) = 3.9A(3.9A)

AC19V10 (Amazon)
Input: 100-240V ~ 1.3A(1.3A)
Output: 19.5V(19.5V) = 4.74A(4.74A)


my question is, what would happen if i use the newer supply with the higher amperage? I haven't tried it yet because i don't want to burn anything out.

thanks for any help!


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Oct 13, 2010, 01:33pm EDT Reply - Quote - Report Abuse
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Edited: Oct 13, 2010, 01:34pm EDT

 
>> Re: Using a power supply a bit bigger then the original? (Laptop power)
That should be fine. Your laptop will only draw as much current as it needs, so going higher shouldn't hurt anything (going lower could be bad). The voltage, however, should be the same.

john albrich Oct 13, 2010, 01:47pm EDT Reply - Quote - Report Abuse
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Edited: Oct 13, 2010, 02:05pm EDT

 
>> Re: Using a power supply a bit bigger then the original? (Laptop power)

The higher Amps rating on the output simply means that it is capable of supplying more current to the computer. In general, this is a good thing as it means the new power supply is more robust than the one it replaces.

As long as the output voltage is the same, it fits where it needs to, and the heat generated and distribution of that heat is similar you'll be fine. However, if they changed the heat sinks to allow more heat to be dissipated by the power supply that does mean it could contribute to over-heating in general, and localized over-heating of adjacent components.

If the power supply is the same form factor, and any heat sinks and shielding look to be the same and in the same places, this likely won't be a problem, but you do have to take into consideration that there is a remote chance that IF the new power supply generates more heat in an enclosed space, it might cause overheating inside the case.


edit to add:
I see McFly posted while I was entering my reply...today's being one of those days...
Another observation about the higher output amps rated unit, is that it also means that for a heavy electrical load, the output voltage(s) will tend to be more stable than the lower-rated unit. Which is also a good thing.

Michael Schiele Oct 13, 2010, 01:51pm EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)
@john albrich are you referring to a desktop power supply? I'm talking about a laptop power supply specifically for a Sony Vaio VGN-SZ750N notebook. is heat really still an issue?

Oct 13, 2010, 01:57pm EDT Reply - Quote - Report Abuse
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Edited: Oct 13, 2010, 01:58pm EDT

 
>> Re: Using a power supply a bit bigger then the original? (Laptop power)
Michael,

It does look like John is talking about a desktop PSU. However, the points about amperage and voltage remain valid for any kind of power supply. :_) Your replacement should be fine.

Michael Schiele Oct 13, 2010, 02:00pm EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)
thats awesome! thanks so much for your help!

john albrich Oct 13, 2010, 02:08pm EDT Reply - Quote - Report Abuse
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Edited: Oct 13, 2010, 02:16pm EDT

 
>> Re: Using a power supply a bit bigger then the original? (Laptop power)
No. I am not talking about a desktop power supply. I am talking about a notebook power supply. Even a minor design change such as I described can make a significant difference in how and where the heat is dissipated, especially in the unique configurations found in notebooks. In general, he will likely be ok, but it's something that can't be ruled out entirely.

However, I was talking about the INTERNAL power supply, not an EXTERNAL brick. If you were talking about a brick than the internal design changes of a brick obviously would have no impact on internal notebook case heat distribution.

Oct 13, 2010, 02:13pm EDT Reply - Quote - Report Abuse
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Edited: Oct 13, 2010, 02:16pm EDT

 
>> Re: Using a power supply a bit bigger then the original? (Laptop power)
John,

My apologies for assuming. You're clearly a lot more knowledgeable than I when it comes to electricity. I just know that it hurts when I lick it.

It sounded like you were saying that if the PSU generated extra heat, then it would cause the laptop to overheat as well -- which I think is why both Michael and I thought you were referencing a desktop PSU.

john albrich Oct 13, 2010, 02:18pm EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)

It's just because I thought he was talking about the internal power supply and not an external brick. I edited my post to clarify.

Apparently it is an external power brick that's involved, right?

Oct 13, 2010, 02:23pm EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)
Wait ... I thought that a laptop power "brick" was the power supply? :blush:

Michael Schiele Oct 13, 2010, 02:27pm EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)
I am talking about a laptop brick power supply. I'm in the same boat with McFly, i thought the brick WAS the power supply?

john albrich Oct 13, 2010, 02:49pm EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)

There are also power supplies inside the notebook. Here's one block diagram. This one shows a laptop that uses an external brick (upper right) to convert the AC mains to a lower DC level which is then input to the various power supply subsections within the notebook
http://focus.ti.com/docs/solution/folders/print/342.html to provide power for various parts of the computer.

I was thrown by his use of part numbers in the original post and I over-thought it. I should have asked up front if he was referring to a brick rather than an internal power module.

Oct 13, 2010, 02:56pm EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)
Ah. Thanks for that, John.

Meats_Of_Evil Oct 13, 2010, 04:53pm EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)
Yeah John's the man. He's like Gandalf sometimes though and speak in riddles.

I didn't even know laptops had internal PSU's lol.

-------------------------------------------------------------------------------------------------------------------------
Everything I write is Sarcasm.
Dr. Peaceful Oct 14, 2010, 12:25am EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)
I learned something new, too. Thanks John, nice diagram.

Come to think of it, it's not easy to visualize a laptop has an internal PSU board, in addition to an AC adapter (brick). But for ITX desktop boards, this can be seen obviously. I have a mini-ITX box I built myself, it has a separate 60 Watts PSU circuit board supplying power to the main board via a 20pins connector. It's the same concept for laptops, only the PSU board is on the same board as the main board. In fact, many newer mini-ITX boards are doing the same thing, combining the PSU onto the board, no more 20 / 24 pins power connector.

Oct 14, 2010, 01:34am EDT Reply - Quote - Report Abuse
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>> Re: Using a power supply a bit bigger then the original? (Laptop power)
What exactly is the internal "PSU" doing in a laptop?

I had always assumed that the power "brick" on a laptop was "the" PSU, since that's what converts from AC to DC. But only having one output (to the laptop), that differs from a desktop PSU, where most components plug into the PSU.


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