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Question

A/ c adapter

by mcabby01 / January 11, 2013 8:36 PM PST

I have a Gateway mt6916 with a a/c adapter of input ac 100-240v 1.2a, output 19v 3.42a that is not working. I have another adapter for an HP with input 100-240 v 1.5a and out put 19v 3.16. It plugs in to my computer fine so hopefully that won't be an issue, but before I connect to electricity, what about the different amp and volt thing. Don't want to fry my computer. Thanks for any help!

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All Answers

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Answer
Adapter
by pgc3 / January 11, 2013 11:56 PM PST
In reply to: A/ c adapter

If it were myself I would not go that route, do OEM only, I have seen too many systems screwed up by doing just what you are attempting to do. It is your call but it takes VERY little to toast a laptop.

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Answer
Re: adapter
by Kees_B Forum moderator / January 12, 2013 12:01 AM PST
In reply to: A/ c adapter

19V is 19V, so that HP one should work fine.

Kees

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Current
by pgc3 / January 12, 2013 12:07 AM PST
In reply to: Re: adapter

It isn't the voltage that kills you it is the current.....= amps..There is also and issue with the input/plug of the adapter to the L/T typically HP and Gateway are different ....IMOP it isn't a good idea..

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Exactly
by Jimmy Greystone / January 12, 2013 9:36 PM PST
In reply to: Current

Exactly. At least someone around here knows their Ohm's Law.

In this case, the output is off by about half an amp on the HP, so who knows if the Gateway unit would even turn on, but even if it did, you'd be hanging a giant neon sign of a bulls eye on the Gateway, tempting the fates to fry the unit.

But so long as you don't live anywhere near me, where I'll be affected by the resulting electrical fire when the AC brick goes up in flames, knock yourself out.

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I do know Ohm's Law
by ChuckT / January 13, 2013 3:01 AM PST
In reply to: Exactly

I do know Ohm's Law, and I have known it since the electrical courses I had taken it back in High School, the two years I went through in Electrical Technology college courses, the nine months of it I went through it in the Navy ET "Class A" School in the Great Lakes, the "Class C" schools I also took, and the 3 years of active service as an ET aboard ship. Then those 30 some years as a computer tester, designer, programmer and writer at Xerox where it was also useful to know about electrical basics and the advanced academics that I had too.

Current is not forced into a device, current is the result of a voltage applied across a resistance. If you have (for example) a 19v source applied across a 10 ohm load the result will be a (19/10) 1.9 amp drain of the source - AS LONG AS the power source can supply that much current. The OP's second power supply is rated at just 3.19A, whereas the original was rated at 3.42A, does not mean that 3.42A was ever drawn from the original power supply. Only that it was rated to reliability deliver that much, if needed.

And just because a power supply is rated at 3.19A does not mean it can't deliver 3.20, or 3.21 or even 3.42. As you get beyond the rated limits of a power supply what generally happens is that more ripple (less steady) may be riding on the DC voltage. Few power supplies have a cutoff point so tightly tied to it rated specs.

More than likely, once the computer is up and running, past the initial surges, the actual requirements of the power supply will be much less than those ratings. So, again I say, if the plug fits, and the voltages are so very close, and the current capability is about there or better, just try it. I'll bet my over 40 years of experience that nothing bad happens.

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Answer
Almost identical ratings
by mjd420nova / January 12, 2013 5:28 AM PST
In reply to: A/ c adapter

The ratings are very similar. The current rating for the new one is just slighky higher. The plug in is a different story. The connector may fit but the connections for power may be different and could indeed turn the laptop into a doorstop. If you have a multimeter, check the voltages and note the position on the connector. If and only it the connections match should you attempt to power things up.. Smart thinking to ask first.

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Adapter
by pgc3 / January 12, 2013 6:07 AM PST

Still not a good idea, all it takes is a couple of milliamps variation and BYE BYE....not to mention physical input differences....but then it ain't my laptop.....

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Answer
As long as it fits and the voltage is the same
by ChuckT / January 12, 2013 6:52 AM PST
In reply to: A/ c adapter

As long as it fits and the voltage is the same (or even just about the same, say within 10%, but that is a guess) it may power the unit, IF the current capability (the number of amps) is adequate.

There are several things to meet here:
[*]The plug fits
[*] The polarity is correct! VERY IMPORTANT, however most plugs now do match the polarity anyway.
[*] The voltage is correct. Having a voltage a bit lower may still work. And having a voltage a bit higher may not be too bad either, since most power circuits have a tolerant zone. I would not expect more or less than the expected range within 10% margin.
[*] Finally the current capability. If your supply is more than the needed current there is NO PROBLEM. That is only the maximum the power supply can deliver. The computer will only take as much as needed to meet its requirement. As long as the power supply can deliver. Think of a 12v car battery. It can deliver 100 to 300 amps! (perhaps more) but if you connect a 12v 1 amp light bulb to it, it will work fine. It does not blow up. The lamp will only consume the needed 1 amp.

If the power supply is short on being able to deliver the expected current (the amps) then MAYBE it might not work. Usually the number you see on the side of the computer, as to how much current is needed is a bit on the high side. That might be when/if all the plugged in devices are connected at one time, or the surge needed at turn on time.

As for the number on the side of the power supply, that may be a bit on the high side, as well. The company that put the number on the side wanted to positively promote the actual capabilities of the power supply it made.

All I am saying is, if the plug fits, the polarity is correct, and voltage is about right, just try it. Even if the power capability of the power supply is a bit low, you might be surprised. If it can't deliver the current then usually all that happens is your computer will not come up.

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Answer
19 Volts = 19 Volts.
by R. Proffitt Forum moderator / January 12, 2013 10:20 AM PST
In reply to: A/ c adapter

But you know because of the LAPTOP BATTERY FIRE issue that occurred a few years ago that makers had to introduce some smarts into the detection of both battery and charger.

Just because it's the right voltage and Amperes does not mean it should work anymore. While it should be fine and if the polarity is the same it should be fine does not mean it will work.

Before you reply, be sure to read about the LAPTOP BATTERY FIRES and about the lawsuits that meant the end of simple designs.
Bob

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Laptop fires
by pgc3 / January 12, 2013 2:06 PM PST
In reply to: 19 Volts = 19 Volts.

Yes Bob, Sony had an issue with that a few years back and there were some lawsuits.

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The chargers don't cause the Li batt fires
by ChuckT / January 12, 2013 3:58 PM PST
In reply to: 19 Volts = 19 Volts.

The majority of the Li (Lithium Ion) battery fires was because of the faulty construction of the battery itself, not because of the battery charger. Sure you can construct a charger that might be able to detect the battery starting to fail (abnormal heat, abnormal current draw) but the real fix was to better the batteries.

When Dell recalled my batteries they let me keep my charger. When my Palm Pre battery started to malfunction the battery started to expand. I just removed and replaced the Li battery.

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True. And it still resulted in
by R. Proffitt Forum moderator / January 12, 2013 11:24 PM PST

And the issue caused the makers to put ID chips in the batteries and also on chargers. Gone are the days when you would just match up the Volts and Amperes and you would be fine.
Bob

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That ID chip
by ChuckT / January 13, 2013 2:13 AM PST

That ID chip is there more so for the benefit, the profit margin, of the manufacturer. They want you to replace only with their known quantity. Not that it is better than any others, but they can't otherwise know where or what you use.

I have one customer who has a Dell laptop that was reporting an incorrect battery, even though it was the correct Dell battery. The fix was to update the BIOS, which then correctly identified the battery. I could have just gone into the BIOS and disabled the checking of the battery, but the new BIOS either did that for me, or relaxed some parameters.

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That's a common view of this.
by R. Proffitt Forum moderator / January 13, 2013 2:17 AM PST
In reply to: That ID chip

But the fact that litigation happened meant the makers had to implement ways to lock out non-maker batteries and chargers.

It's very simple. If you allowed 3rd party chargers and batteries then the lawyer extends that to mean the maker sanctioned such use.

Take this back to our legal system. The makers did not do this for their bottom line. They don't want to increase the cost of the products.
Bob

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