I'm working on a DIY Mirror Touch frame and am on the final stages connecting everything.

I have the issue where I was unable to find a deep enough aluminum frame and therefor have the issue where the power cable would protrude from the backside (see first image below and red line).

I've managed to disassemble the DVI connector and reduce the protrusion there.

For the power connector, I would appreciate support with soldering the Power adapter wires to the PCB - as I have no idea which solder point on the PCB should be associated with which wire (DC Live, Ground or DC neutral). I would de-solder and remove the power connector on the PCB and solder the wires directly (and then add a good amount of hot-glue).

Red line shows power connector protrusion

enter image description here

enter image description here

enter image description here

  • 1
    Sorry, but electronics repair doesn't fall under "home improvement" as defined by this site. You might try electronics.stackexchange.com. – isherwood Feb 19 '19 at 17:45
  • 2
    You plan to hook mains power to those connector locations? Can you promise to post a video of the initial powerup, no matter what happens?? – Harper - Reinstate Monica Feb 19 '19 at 18:26
  • Thanks. My question might need improvement as it seem so many are focusing on the power adapter... that's not my concern as the power adapter is what came with the LCD (19V adapter). I looked for other Exchange sites and thought that this site (diy.stackexchange.com) would fit at I am doing a touch screen mirror by myself. I checked electronics but seemed far more technical than just "what wire goes where". Still appreciate the feedback. – Skuli Axelson Feb 19 '19 at 18:58

I doubt that cable is carrying household voltage. It's probably DC voltage in the 12-24 volt range from a power supply brick.

Use your multimeter to figure out which part of the connector on the cable is positive and negative. Then you can desolder the socket from the board, cut the connector off the cord, use the multimeter to identify positive/negative in the cable and solder it to the circuit board.

If I had to guess, the two pins sharing a trace are probably positive, and the third pin looks to be attached to the ground plane and therefore probably negative.

enter image description here

| improve this answer | |
  • Thank you @longneck. It is DC voltage and power adapter for LCD screen (19V). I'm not concerned about the power cord end. I'm able to measure what which wire is. it's the PCB side I'm not sure where the wires go once I remove the power connector from the PCB. – Skuli Axelson Feb 19 '19 at 16:41
  • 1
    They go in to the holes left behind by the connector when you desolder it. – longneck Feb 19 '19 at 17:09
  • I guess what I could do is connect the power adapter as it is (stock) and then measure with a multi meter under the PCB (carefully). Didn´t think of that until I read your reply. Thank you again. – Skuli Axelson Feb 19 '19 at 19:01

Mains electricity is not a toy!! Low voltage DC is a toy, which is how you got misled.

Mains will steal your girlfriend, wreck your car, cancel your fire insurance, burn down your house and kill you. It is a completely different beast. (It's a very slightly less psychotic version of mid-voltage DC, which made a serious college try to kill 3 astronauts the last time it was trifled with. AC, at least, has a zero crossing that will often snuff arcs).

Anytime you get an urge to do something with mains electrical, put down the soldering iron (you'll never use it), come here and talk about what you want to do. We'll run you through it the right way, that meets Code, will save your fire insurance, and will be safe. Humanity's best-practices at handling mains power safety (Code) are so refined that it looks easy, and that makes mains AC seem harmless. As such, Code can seem stupid. It's not.

I'm sorry to give you the finger-wag, but you specifically asked how to connect AC live, AC neutral and ground.

But you're in luck

That's a Barrel connector. Mains power would never be on that because it wouldn't have the dielectric strength. The weird lump in the power cord is not merely to annoy you, it's to knock AC mains power down to low voltage DC.

By the way, the reason so many manufacturers do that, the thing with the wall-wart, is it allows them to sidestep the bulk of the UL listing process. They only need to clear the low hurdle for low-voltage DC machines, then they toss in a commodity off-the-shelf wall-wart that somebody else already got UL listed. That's why wall-warts almost never have any labeling to say which equipment they go with.

The Electrical Code has sweeping exemptions for low voltage devices under 30V (talking to you, NASA) that are also under 55 watts. Your device probably falls under that exemption.

You only need to figure out how to convert mains to the correct low voltage safely (e.g. By simply using the power block that came with the machine), how to site the power supply (plugged into a nearby receptacle is pretty safe), and how to connect the wires.

| improve this answer | |
  • Shows how much I know about electricity and the correct terms :) I am NOT going to connect wall outlet/power AC to the PCB. I'm only planning to cut of the LCD screens included power adapter (19V) plug/jack off and solder those wires to the correct locations on the PCB. I was just unsure which wire from the power adapter should be soldered to which pin on the PCB. – Skuli Axelson Feb 19 '19 at 21:59

First off as pointed out in another answer none of those pins are for AC mains, they are all for the outputs of a power brick.

What I would do is first check if the cable is visible asymmetric, if not use something (tippex may work nicely) to mark one side of it so you can tell which wire is which after cuttin cut the connector off the power brick, then use the multimeter on continuity to work out which wire in the cable connects to which solder pad on the board.

| improve this answer | |

Not the answer you're looking for? Browse other questions tagged or ask your own question.