Low voltage mystery

[Radman2020]

I have undercabinet lights that are low voltage. They work xenon pucks just fine. I want to convert to low voltage LEDS. Supposedly these are 12V DC but when I hook 12V DC LED pucks up, they don't work.

There is a switch to turn these on that is 120 volts. Somewhere buried behind the wall is a 120 to 12VDC converter. I can't access it. I am assuming there is too much current to the lights so the LEDs won't work... maybe more than the 12V. I bought a multimeter but it doesn't show any voltage. I put the wires together and I get a spark so I know there is power. Maybe I am using the multimeter wrong? I put the probes to each end of the wire. I also put it to one end of the wire and to a ground. Nothing.

In the end, I want the LED's to light up but they don't seem to want to respond to the power getting to them. Is there anything I can do??

 

[AC Power]

As electricians, we would determine this differently, but I am giving advice to a homeowner.

Try connecting just one (1) of your LED's to that 12vdc supply your saying is arcing. Does it light the one (1) LED?

If so, add a second LED to it, does it too come on?

Do they ALL fail OFF when you add a third LED?

This way you can verify if the VA of the 12VDC converter is sufficient.

 

[Radman2020]

First, there is a label on the connector box that says 12V DC but honestly, I have no idea if it is truly DC or if it is low volt AC. The multimeter isn't helping me there.

When I hook a low voltage AC/DC LED to it, it flashes for an instant. It seems to be burnt out at that point.

Any advice would be useful. The xenon/halogen low voltage bulb works just fine.

 

[AC Power]

Well, you would need to set your multimeter to VOLTS, and ensure it is DC volts.....not AC. Touch the two leads of your tester to the two leads coming from the 12VDC converter (that wires that sparked, that is). If you get a reading +12VDC or -12VDC, then your converter is emitting 12vdc. Check that first.

 

[AC Power]

And remember too, LED are polarity sensitive. You must have the + of the supply going to the + of the LED. Same is true for the negative.

If your unsure, connect one LED to the converter one way, observe. Flip the two wires around, observe.

 

[Radman2020]

honestly, I am not sure which is the DC and which is the AC... however, here are the pictures of what I get.

 

[AC Power]

Your second picture is correct for dial placement.

However, unplug your RED test lead from the meter and move it one space to the right (directly above "10ADC"). Then show me again.

 

[AC Power]

And move your black test lead to the right (center) hole, leaving the left hand hole vacant,

 

[Radman2020]

It registers as 0.00 but the wires all get very hot very quickly.

 

[Radman2020]

oops. I didn't see the second post about the black test lead. let me try that

 

[AC Power]

Actually, my bad about the last comment.....I see your meter is actually IEI.......leave the black lead in the leftmost hole, and put the red lead in the rightmost hole. Mu bad..sorry.

 

[Radman2020]

When I do what you say, it registers as 0 and the wires all get hot quickly.

Not sure what IEI is. When I did move the black to the middle, I got the following

 

[AC Power]

Take a picture of the wires coming from the 12vdc converter, and take a picture of your meter with it's leads....in one picture if possible. Post it, and I will PhotoShop draw the connection for you. I'll do this as soon as I can, but I might need some sleep. So I will "draw" in HOW you need to connect this....just post a few pics of BOTH the meter, AND the wiring from the 12VDC converter. I will respond in the next 24hrs.

 

[Radman2020]

So here is the problem.....

If I could get to the converter, I would have replaced it with a dedicated LED converter. It is buried somewhere in the wall or the basement ceiling behind drywall... and I don't know where it is to uncover it. All I have is a wall switch which I think is the 120 AC power.

All I have is the wires coming out of my cabinet. Silly me. I thought I could just hook a multimeter up and it would tell me the voltage and whether it was AC or DC. Whatever it is, it runs low voltage halogens but immediately burns out leds.

 

[AC Power]

Alright, now I understand better.

Now, one principle of electrical theory is such that heat is produced when AC or DC are touched together.

Having said that, if the wall switch is ON, and you touched the two leads from your converter together, they would begin to heat up very quickly....bad news....let them apart (open) right away. That is called a dead-short (AKA "short circuit"). This is true of AC or DC, and also true regardless of voltage.

Do you still have the old zenon pucks? If you do, take a picture of the them; particularly the cat # on the back. Ensure you include the pictures of the two wires coming off the back of the puck housing/chassis.

 

[AC Power]

Failing this, I will offer you my cell number for a mutually agreeable time call......it would be easier that way. It's up to you.

 

[Radman2020]

Here is one that is still hooked up.

 

[AC Power]

That is an AC supply, at 12volts.

So, being DC, your new LED lights won't work from that in-wall converter. If you refeed the new LED lights from another source, your likely going to want to dim them anyways. So be sure to insulate (put wire nuts and/or black tape) each of the two wires independently coming from the old converter so the wires CANNOT touch each other. This is a back-up safety. Push them into the wall and ignore them. If you want a suggestion on how to refeed the lights, take a few pictures of your kitchen and post them.....I'll see if I can offer any help.

Otherwise, Sorry about that.....we've tried.

 

[Radman2020]

confused. The bulbs I have are supposed to work on AC or DC. They flash when I hook them up and are then dead. Also, can't you tell what the voltage is by the multimeter? What is the multimeter telling you?

 

[Radman2020]

as for a whole new system, I have a new system but I can't really fish the lights to all the places I want them. I would want one place to plug in the transformer/converter (so I could control it by alexa)....but I have to get behind tile etc... If the unit I sent the picture of is AC, isn't there an LED that will work with it if these AC/DC lights won't?