LED won't turn off

Thread Starter

nyjumpee

Joined Mar 19, 2019
10
Hi! I replaced my over the range Microwave down-light with an LED. . .looks great but won't turn off. . .apparently there's still just a little bit of current running through when the switch is off and it's enough to keep the LED on. .while not full bright, it's bright enough to see light on the stove during the day. I don't know much about resistors, etc. but is there something I can put inline on one of the supply wires to suck up enough juice so the light goes out? Again, I don't know resistor specs, etc. so if one could be so kind as to specify exactly what I'd need and how and where to install it that would be most helpful. . .thanks in advance!
 

ci139

Joined Jul 11, 2016
1,464
(-1-) LED-s do not like heat — the more heat the less service life . . . besides they have a "half-life" - is - they loose brightness over time
(-2-) You won't be affecting nor the climate warming not your energy bill continuing using the incandescent light — ovens take over 1kW the light too illuminate these takes 15W or 25W -e.g.- below 2%
 

Thread Starter

nyjumpee

Joined Mar 19, 2019
10
Is this a dimmer switch or a simple on-off switch?
Hey AlbertHall! Thanks for the reply. The "switch" is just a button marked "light" on the front of the Microwave. Push it once, the light comes on, 2nd push dims it a bit. .3rd push turns it off. . it used to anyway with an incandescent bulb in there. . just wanted a higher temperature color so figured this 6000k LED would do it. . same bulb worked fine in my last microwave. . just replaced the microwave with a new stainless model and discovered this issue. . .apparently it's now unusual. . .right in the description on Amazon if you read the fine print, it says "bulb may stay on very dimly when off". . .gotta be a way to cut power completely, right? Thanks!
 

Thread Starter

nyjumpee

Joined Mar 19, 2019
10
(-1-) LED-s do not like heat — the more heat the less service life . . . besides they have a "half-life" - is - they loose brightness over time
(-2-) You won't be affecting nor the climate warming not your energy bill continuing using the incandescent light — ovens take over 1kW the light too illuminate these takes 15W or 25W -e.g.- below 2%
Hey ci139! Thanks. Not really concerned about the power usage or bulb life. . .just the color temperature. . .can't find an incandescent E17 base bulb that doesn't look "warm" or "yellow". . .For now I guess it's an always on Night-Light. . .but again, gotta be a relatively simple way to soak up that little bit of constant juice that's enough to make that sucker glow. . .thanks again.
 

Thread Starter

nyjumpee

Joined Mar 19, 2019
10
If it was easy the manufacturer would have done it as they know about this effect.
Hey AH. . I'm gonna guess that there's still a relatively easy solution but in the interest of selling bulbs, they didn't include a resistor to solder inline which would complicate things. . .when I was researching it online, I came across a guy doing LED's in his car. . .same issue. . .it was a double-ended bulb (contacts on each end). His solution was to pull the bulb out and clamp one end of a resistor to each end of the bulb and snap it back into place and apparently his problem was solved. . . I just don't know squat about resistors, voltages, ohms, etc. . .can't imagine there's not something that'll go inline to soak up that little bit of power that dimly lights the bulb. . .especially since with the exact same bulb didn't do this in my last microwave. . .
 

Dodgydave

Joined Jun 22, 2012
9,162
I would put a load resistor across the bulb socket, sounds like the led is higher in resistance than the incandescant bulb, and the Triac is leaking small current,.

Try a 15W bulb and see if it stops.
 

Thread Starter

nyjumpee

Joined Mar 19, 2019
10
I would put a load resistor across the bulb socket, sounds like the led is higher in resistance than the incandescant bulb, and the Triac is leaking small current,.

Try a 15W bulb and see if it stops.
Hi Dodgydave! Thanks for your reply. I found this video on Youtube
. Can't say I understand it or if I can do anything about it. .I don't know what a "load resistor" is or a "Triac" but I'm willing to learn. Is that "load resistor" something that I can splice inline in one of the feed wires? Also, regarding trying a 15 watt bulb. . ."currently" using this bulb https://www.amazon.com/dp/B074RGCPK1. It's a 4 watt LED. If I could find an incandescent bulb that delivers the same color temperature I'd do that. . .LED is all I can find in the 5000-6000k spectrum that fits this e17 appliance bulb socket. Thanks again!
 

dl324

Joined Mar 30, 2015
10,751
I don't know what a "load resistor"
Don't be fooled into thinking this is an easy hack. If it's a line voltage LED that we're talking about, a resistor across the LED is probably a bad idea. You need to consider the resistor working voltage and wattage. Putting a resistor inline won't help.
 

Thread Starter

nyjumpee

Joined Mar 19, 2019
10
Don't be fooled into thinking this is an easy hack. If it's a line voltage LED that we're talking about, a resistor across the LED is probably a bad idea. You need to consider the resistor working voltage and wattage. Putting a resistor inline won't help.
Thanks Dennis. . .I'm beginning to see that. . . just for ha-ha's, here's a response that I got in another forum "The problem is caused by capacity coupling between the live feed and the switched wire to the lamp. A resistor in parallel with the lamp would solve the problem but would consume power when the light was switched on. I have used a capacitor in parallel with the lamp. This has current passing through it when the lamp is on but it is 90 degrees out of phase with the voltage so it does not consume any power so it does not get hot. I use a contact suppressor (which is a capacitor with a low value series resistor.) rather than just a capacitor. The reason I use these is that they are available with flexible lead connections so I can just connect it to the lamp holder connections. This is the sort of thing I am talking about. " Also found this video that explains at least WHY it happens. . .https://www.youtube.com/watch?v=_bgUy6zA0ts . Maybe wiring another light inline with it will suck the extra juice? Maybe I should just give up? Thanks again ;-)
 

ebeowulf17

Joined Aug 12, 2014
3,274
You've mentioned wiring things inline with it several times, which I assume means putting in serial with the LED. That won't help, because that still means that the only path to complete a circuit is through the LED, and if current is going through the LED, it will light.

What you need to do is put something in parallel with the LED. The contact suppressor (snubber is the term I'm used to) linked in your last post looks like a pretty good choice.

You can also use a high value resistor, but you have to get a high-wattage resistor, even if you wouldn't otherwise need the wattage rating, in order to make sure it has a suitable voltage rating. The link below is for a 2W resistor, rated for 500V. It will only be dissipating roughly 1/4W when fully powered, and presumably much less when serving as a bypass path for leakage current.

https://cpc.farnell.com/multicomp-pro/mcf-2w-220k/res-220k-5-2w-axial-carbon-film/dp/RE07862

I think either solution is likely to work well - the key is putting it in parallel with the LED, and being very careful making your connections to keep everything safe.
 

MisterBill2

Joined Jan 23, 2018
6,072
Hey AlbertHall! Thanks for the reply. The "switch" is just a button marked "light" on the front of the Microwave. Push it once, the light comes on, 2nd push dims it a bit. .3rd push turns it off. . it used to anyway with an incandescent bulb in there. . just wanted a higher temperature color so figured this 6000k LED would do it. . same bulb worked fine in my last microwave. . just replaced the microwave with a new stainless model and discovered this issue. . .apparently it's now unusual. . .right in the description on Amazon if you read the fine print, it says "bulb may stay on very dimly when off". . .gotta be a way to cut power completely, right? Thanks!
Why do you think that it is so important to switch the low powered LED bulb off? Consider that the control circuit was delivering the same current to the incandescent bulb, but it was not illuminating. So your circuit is not using any more power than it would use with any other light.
 

Thread Starter

nyjumpee

Joined Mar 19, 2019
10
Why do you think that it is so important to switch the low powered LED bulb off? Consider that the control circuit was delivering the same current to the incandescent bulb, but it was not illuminating. So your circuit is not using any more power than it would use with any other light.
Hey MisterBill ~ Thanks for the reply. Really not concerned about the power it's using. . . just would like the option to turn the freaking thing off. . ya know, like any other light? You're not the only one that's responded with "just leave it on" and yes I completely understand that the electricity usage is next to nothing, the LED will last forever, etc. Love the color of the light. . just would like the simple option of being able to turn it off. If this is more difficult than I thought then I'll just go back to an incandescent. . thanks ;-)
 

Thread Starter

nyjumpee

Joined Mar 19, 2019
10
You've mentioned wiring things inline with it several times, which I assume means putting in serial with the LED. That won't help, because that still means that the only path to complete a circuit is through the LED, and if current is going through the LED, it will light.

What you need to do is put something in parallel with the LED. The contact suppressor (snubber is the term I'm used to) linked in your last post looks like a pretty good choice.

You can also use a high value resistor, but you have to get a high-wattage resistor, even if you wouldn't otherwise need the wattage rating, in order to make sure it has a suitable voltage rating. The link below is for a 2W resistor, rated for 500V. It will only be dissipating roughly 1/4W when fully powered, and presumably much less when serving as a bypass path for leakage current.

https://cpc.farnell.com/multicomp-pro/mcf-2w-220k/res-220k-5-2w-axial-carbon-film/dp/RE07862

I think either solution is likely to work well - the key is putting it in parallel with the LED, and being very careful making your connections to keep everything safe.
Hey Ebeowulf17! Thanks so much for that helpful reply and for explaining why, with my extremely limited electronics knowledge, that putting something "in line" won't work. So, by "in parallel" that means that one end of the resistor/snubber needs to be connected to one wire/terminal going to the light and the other end of the snubber needs to be connected to the other wire/terminal? What values (?) or exact part number snubber should I be using for a 120v 4w LED?
I have built a Cmoy amp before but that was by following explicit directions online with practically no idea why it worked so I have the mechanical ability to solder, wire, connect, etc. Thanks again for your help!
 

MisterBill2

Joined Jan 23, 2018
6,072
Hey MisterBill ~ Thanks for the reply. Really not concerned about the power it's using. . . just would like the option to turn the freaking thing off. . ya know, like any other light? You're not the only one that's responded with "just leave it on" and yes I completely understand that the electricity usage is next to nothing, the LED will last forever, etc. Love the color of the light. . just would like the simple option of being able to turn it off. If this is more difficult than I thought then I'll just go back to an incandescent. . thanks ;-)
One simple way that may allow it to switch off completely is to add a series diode to the LED feed. That will drop the voltage a bit and it may be enough to stop the glow. LEDs are very non-linear and so reducing the voltage just a bit may be all that you need.
I am guessing that the lights are 120 VAC powered, and so the polarity of the series diode may matter. The diode would need to be something like a 1N4002 or higher voltage rated.
 

Tonyr1084

Joined Sep 24, 2015
4,538
I would put a load resistor across the bulb socket, sounds like the led is higher in resistance than the incandescant bulb, and the Triac is leaking small current,.

Try a 15W bulb and see if it stops.
Would not recommend a resistor, but this is exactly what's happening. If you've ever opened a microwave oven (not recommended for good reason) the board that controls the oven also controls the fan speed and the light intensity. When "OFF", as Dave said, there is leakage. That's why the LED bulb stays on either partially or may flicker. I've had similar issues with a standard motion detector light switch and LED's on the circuit. When I upgraded my basement lighting I put a motion detector light switch (MDLS) in. When you entered the laundry room the lights would come on and stay on as long as motion was detected. Five minutes later, after all motion detection ended the lights would shut off. Later I upgraded the bulbs to LEDs. As soon as I removed the last incandescent bulb the LEDs began to flicker. I had to leave at least one incandescent bulb in the circuit in order to make the LEDs go fully off. All because there was a small leakage current going on. And the inc' bulb didn't have to be high wattage either.

In my bedroom I have table lamps aside the bed. I built a box with light dimmer touch controls. The ran a small wire up the back side of the bed post. All you had to do was touch the wire and you turn the lamp on low. Touch again, medium. Then high. Then off. You could plug any lamp into it. But you couldn't use LED bulbs because they'd flicker or glow constantly. The solution was to have a single inc' bulb. Since the lamps there now have a small night light in them as well as the standard bulbs, replacing the standard bulbs with LED and the inc' night light, the lamps work perfectly. Fully dimmable and fully off when off.
 

MrChips

Joined Oct 2, 2009
21,129
That sounds like the best solution, i.e. put a low wattage incandescent light bulb in parallel with the LED lamp.
However, this would require getting at the wiring.
 
Top