Okay to supply more amps? Use a 14V 4A 56W power adapter on a 14V 3.21A (45W) monitor?

Question

I have a Samsung 4K monitor, LU28E510DS/ZA (Costco exclusive variant), with a back panel describing DC14V 3.21A.

I cannot find an exact replacement power supply. I found one that is close at 14V 3A for 42W rather than 45, but not sure if that is enough power.

I found another at 14V 4A (56W).

➟Is okay to use a power supply at the appropriate voltage but with a higher amperage?

If not, is the 14V 3A close enough to use for a 14V 3.21 monitor?

This Humanities-major is at the limit of his electrical engineering knowledge.

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According to this fellow, Voltage must match between monitor and power supply, and Amperage on the power supply can be higher than is required.

• Voltage is pushed to the device by the power supply, so must match.
• Amperage is pulled by the device from the power supply.

So excess amperage capability by the power supply is a good thing, not a problem.

Is that correct?

Solution

TL; DR: Your / Leo Notenboom's assumption ("Voltage is pushed, Amperage is pulled") is correct, but there are more things to take into consideration than just Volts and Amperes: polarity and connector-compatibility.

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The more current your PSU can handle, the better (if we are leaving efficiency aside). The monitor will only draw as much current out of it as it needs, so even a 1A monitor would be okay with a 10A PSU. If it was the other way round (PSU-current < monitor-current), it would be more of a problem, because the PSU probably would not be able to supply enough current to the monitor. The 3A PSU should be fine with the monitor, but in my opinion, it is better to have some reserves than to run the system on full power. The PSU could get very hot, and as a worst case scenario, it could burn (internally) and damage other components (such as the monitor) and/or your home.

The voltage, however, must match - though of course, most of the time, there's a tolerance, so usually it's no problem to e.g. supply a 5V device with 5.5V.

This is not only true for monitors, but all devices (DC as well as AC).

Think of it this way: If more delivered Ampere were ever a problem, your home's circuit breakers would have to be adjustable to whatever devices you have plugged in in that moment. For example, my notebook's PSU has an input-rating of 230V~ 0.5A, while the circuit breaker for my room is rated for 230V~ 16A. The same goes for my LED lamps, my oven,... or, to complete my list of examples, consider (custom-built) computers: While my tower usually idles at ~50W, its PSU is rated for 750W. If more Ampere on the supply-side were harming anything, I wouldn't be able to write this answer, as Watt = Volt * Ampere _{(simplified, of yourse)} and therefore, my computer would have long ago blown up in a michael-bayesque way.

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As mentioned in the comments, when dealing with direct current (DC), it is very important to consider polarity.

To find out about the needed polarity of the connector (your monitor uses the popular barrel connector), you can look at:

• The inscription beneath the DC-IN-Port of your monitor,
• The label of the monitor's original PSU,
• The monitor's manual (if such a thing exists), or
• Measuring the monitor's original PSU connector with a voltmeter

What you're looking for is one of these polarity symbols: _{(By Three-quarter-ten - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3037885)}

There's not much to add to Wikipedia's explanation of this picture:

Diagram showing positive tip polarity on the left and negative tip polarity on the right. To read diagram: The center positive drawing on the left indicates that the center (tip) of the output plug is positive (+) and the barrel (ring) of the output plug is negative (-). Some multi-adaptors use "tip" to indicate the center, but include no explanation that tip is used to mean center.

Your new PSU must match the polarity of your monitor. If it does not and you have sufficient soldering skills, you could simply reverse the connection. (Only do this if you know what you are doing and if you are qualified to do so! Otherwise it could damage the PSU and/or your monitor - or, if you are really messing things up, even electrocute you or put your house and/or cat on fire.)

Note that there could be other (atypical) symbols on your PSUs, including explanatory texts of the polarity. Most of the time, it is very difficult to read them; that's why we have polarity symbols. If you can't decipher those, the safest option is to take a multimeter/voltmeter (a 5€ one will do) and measure the polarity. If e.g. you take the COM-wire (typically the black one) to the outer connection and stick the V-wire (typically the red one) into the center connection, a positive value (e.g. 14.02V) on the display will tell you that the connector delivers a polarity matching the left symbol in the picture above; if the value is negative (e.g. -13.98V), then the right symbol would be the one to go with. This is because the COM-wire is used as Mass, and typically, Mass = -.

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Also mentioned in the comments: Your new plug has to be compatible with the monitor's socket: There are several sizes of barrel connectors, including (but of course not limited to): 5.5mm/2.1mm, 5.5mm/2.5mm, 3.4mm/1.3mm (each outer diameter/outer diameter). So you have to be aware about that, too.

Comments

[Ramhound]

This answer is correct

[flolilo]

I wouldn't say so - 1) Which power supply should work? 2) More current is never a problem (not considering efficiency), but the answer is very vague on this, sounding more like "On monitors, it's okay, but elsewhere (I'm thinking about mobile phones) it could be a problem."

[DrMoishe Pippik]

The only possible issue might be if the power supply is not well filtered. If there is a "ripple" effect in the display, it needs a filter capacitor across the output of the supply. This does not seem likely, though.