My friend just ordered a new power supply on eBay for her Gateway M275. The adapter that shipped with the laptop has these numbers: 19V and 3160 mA.
The adapter she got from eBay is: 19V and 4740 mA.
Is the difference in mA enough to cause problems? The eBay auction did say it was a replacement for the M275, but better safe than sorry.
Thanks,
Jeff
The replacement adapter has more capacity than the original. Excess capacity isn’t a bad thing.
A difference in voltage or polarity is a problem. (Some voltage difference is usually ok, but I’d prefer to be exact on something as expensive as a laptop).
So long as the adapter has the ability to provide sufficient amperage, it’ll be fine. If, on the other hand, you were to connect, say, an inkjet printer drawing 1A (1000mA) to your variable voltage power supply (500mA), then your power supply will rather quickly and permanently cease to provide any current at all. 
I’m not qualified to give a real answer, but I can relate a story that occured in the last week.
I had an IBM T23 laptop with power supply that was rated 16V and 4.5A. When I had it upgraded to a T42 I had forgotten to bring the extra PSU and was warned not to use it even if it did fit.
I had the old T23 power unit sitting around and a co-worker spotted it and decided to use it as a spare for her T42. The T42 power supply is rated 7.5A. She hooked her laptop to it overnight and the laptop no longer functions. Fortunately it has been replaced and she was able to salvage her hard drive so she didn’t lose anything.
I’m not sure what effect the lower amperage power supply did to the laptop, but it wasn’t good. Please check with Gateway to verify the part number is compatible with her computer…especially if she doesn’t have a corporate maintenance contract to replace the machine if it goes belly up.
Based purely on the volatage & amp electrical specs it should have worked just fine, and in fact there are IBM adapters that are spec’d to work on both units. What was the basis of the “don’t do it” warning?
I asked the same question a while back, and Crafter_Man gave a great answer, as he usually does to these electrical quandries.
In general, it is not a problem to use a different power supply (of the same output voltage) that has a higher “maximum current capability.” I say “in general”, because there are times when it may not be desirable to do this:
1. If the OEM power supply is - and is susposed to be - regulated, you simply need to swap in another regulated power supply that has the same maximum current capability as the old supply, or higher. Now you may be wondering… is there any advantages or disadvantages to swapping in a new power supply with a much greater maximum current capability? Yes to both:
Advantages to swapping in a new power supply with a much greater maximum current capability:
Series regulation components in new power supply will have bigger heat sinks, thus the reliability of these components will be better.
Overall better reliability.
Disadvantages to swapping in a new power supply with a much greater maximum current capability:
Less efficient from an electrical power standpoint
Bigger
Heavier
More expensive
2. If the OEM power supply is - and is susposed to be - unregulated, then you had better be careful about swapping in a different power supply. There are two scenarios of why this might be the case:
a. If the device is a variable load, and it uses a specific power supply that is unregulated, it *might * mean that the device *wants * the voltage to decrease as the load impedance decreases. One example is a high voltage power supply for an ion vacuum pump. The ion pump requires an unregulated power supply because the ion pump wants the voltage to decrease as the load impedance decreases.
b. If the device is a *constant * load, and it requires a specific power supply that is unregulated, it *might * mean that the device wants to operate at a constant voltage, and an unregulated supply was used simply for cost and/or efficiency reasons. (All else being equal, an unregulated supply will be cheaper and more efficient than a regulated supply.) If this is the case, be careful about swapping in a different power supply. You can swap in a regulated supply, but make sure you pick one with the right output voltage! To find out what the voltage should be, do not use the voltage output specification of the unregulated power supply. You’ll need to measure what voltage the unregulated power supply is putting out when it is connected to the load, or you’ll have to find out what voltage the load needs through documentation. You also need to be careful about swapping in an unregulated power supply… if the new unregulated power supply has a different source impendence vs. the old one, you may have problems.