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Topic: removal of barrel socket (Read 461 times) previous topic - next topic


Probably a really simple answer, but would like to just check.... before I blow my board.

I have a mega 2560, and would like to remove the power socket from the board, and replace with a wire from the power supply, directly soldered to the board, with a double pole switch in between. However, on the mega it seems there are 2 ground points from the socket to the board. would I need to connect a ground to both points, or just the 1?



Why don't you just connect to the Vin pin?

Either one of the GND pins is fine.



Dec 08, 2019, 07:10 pm Last Edit: Dec 08, 2019, 07:11 pm by araab
thanks for putting my mind at ease. I already have a tft screen connected to Vin, so didn't want to interfere



The multiple grounds on the socket are for mechanical strength, commonly seen with pcb mounted connectors.
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The multiple grounds on the socket are for mechanical strength, commonly seen with pcb mounted connectors.
You learn something new every day. Have just disconnected all the leads which doesn't have a label next to the pin on the screen, and still works perfectly. Thanks for the info MarkT! so now I can put 7-9volts directly to VIN - Thanks Slipstick!


Dec 09, 2019, 12:15 am Last Edit: Dec 09, 2019, 12:16 am by larryd
Just leave the jack in place, tack solder your wires to the jack terminals on the under side of the PCB.

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thanks for putting my mind at ease. I already have a tft screen connected to Vin, so didn't want to interfere
That doesn't make sense.

A TFT screen is not a power supply; and the Vin pin is to supply power TO the Mega, not to draw FROM the mega. Not sure what you're actually doing but you're probably doing something wrong.

Do you know you can connect multiple wires to the same pin? Just solder them together...
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Dec 09, 2019, 03:47 pm Last Edit: Dec 09, 2019, 09:02 pm by ballscrewbob
I assume by the time you read this your display will probably have released its smoke unless it is rated for maybe 10 volts, depending on what is put on Vin.  Vin is the voltage at the barrel jack.  

Also the Arduino is not a power supply. You need to get the Arduino cookbook and read it, this will give you a basic understanding of what you have and can do. There are a lot of on line tutorials that will explain this as well. Use the resources on this web site they are great!

This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!


The tft screen is designed to sit directly on top of the Arduino, and has been working perfectly for a good couple of months. All I'm doing is now incorporating it into a bigger project.



Dec 09, 2019, 09:12 pm Last Edit: Dec 09, 2019, 09:17 pm by DrAzzy
If the display is packaged as a shield (a board sized to fit on top of the arduino with a pin going into all the holes on the board) there's nothing surprising about it connecting to the Vin pin; it is quite possible that the pin isn't even connected to anything on the tft screen shield - shields generally have a pin for every hole, even ones that aren't used (this provides mechanical strength, and simplifies manufacturing, as fewer pieces of pin header need to be placed. Also if they didn't put the unused pins there, newbies would be thinking that their shield was defective because it was "missing a pin").

The barrel jacks typically have three pins - center, outside (these are almost always positive and ground, respectively) and an "insert detect" pin - this pin makes contact with the pin for the outside only when a barrel jack is inserted in the connector. Some devices make use of this as a means of detecting when something is plugged into it (for example, to switch the power source to an external supply if one is connected). It additionally provides improved mechanical strength as noted above, which is particularly important for a connector that could be subjected to mechanical stress if the device is dropped or moved while something is plugged into the connector. If it is not used in a design, it is generally connected to the "outside" pin - this is the case on the Arduino board, which uses a different mechanism to detect whether external power is being supplied.

As suggested above, it's easy to tack wires onto the bottom of these pins without removing the connector. If you need to remove it (maybe for mechanical reasons, or because you're scared that someone who doesn't know what they're doing will try to plug another supply into it while it's powered from the wires), it's not that hard to do - I would try to position the soldering iron so it made contact with all the pins, add some extra solder to make sure there was a good thermal connection, and use an (unpowered) barrel jack in the socket to make it easier to pull out the connector once the solder is melted.
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