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.
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.
As mentioned in the comments, This is not only true for monitorswhen dealing with direct current (DC), but all devices.it is very important to consider polarity Think.
To find out about the needed polarity of itthe connector (your monitor uses the popular barrel connector), you can look at:
DC-IN-Port of your monitor, 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 waypicture:
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 more delivered Ampere were ever a problemit does not and you have sufficient soldering skills, you could simply reverse the connection. (Only do this if you know what you're doing and if you are qualified to do them! Otherwise it could damage the PSU and/or your monitor - or, if you're really messing things up, even electrocute you or put your house or cat on fire.)
Note that there could be other (atypical) symbols on your home's circuit breakers wouldPSUs, 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 be adjustabletake 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 whatever devicesthe 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 have pluggedthat 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 = -.
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 moment, too.
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.
This is not only true for monitors, but all devices. 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.
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.
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.
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:
DC-IN-Port of your monitor, 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're doing and if you are qualified to do them! Otherwise it could damage the PSU and/or your monitor - or, if you're really messing things up, even electrocute you or put your house 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 = -.
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.