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FIXED LG Electric Range LSB5682SW does not keep heat

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AndyLisson1987

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Joined
Mar 13, 2021
Messages
9
Location
Ontario, Canada
Model Number
LSB5682SW
Brand
LG
Age
6-10 years
Hi guys, been looking at a few similar threads to try and diagnose the problem. If I set the bake temperature to 375, it takes forever to get to temp. If and when it does, it doesn’t keep the temperature for long. The broil element works fine and is how we have been heating everything lately.

Based on other posts, I checked the temperature sensor and it tested fine. I also tested the bake (and broil) elements and both had continuity. That leaves me I think with either the relay board or the PCB assembly.

My question is around how I would test the relay board. Other posts have said to test the voltage with the oven set at 350, but I’m not sure how to do that and don’t want to electrocute myself lol. Any help you could provide to narrow it down to whether it is the relay board or PCB assembly would be much appreciated. Trying to avoid replacing both as they are pretty expensive. Thanks so much!
 

rickgburton

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It's most likely the relay board. Set the oven to bake and check for 220 VAC across BAKE and L2 or DLB-OUT. The terminals are marked on the board. L1 is voltage into the board. then, depending on what's selected, bake or broil, it comes out through the relay and to one side of the element. The L2 voltage goes into the board and comes out the Double Line Break relay OUT and is common for both elements.
lg-pwb-pcb-assembly-6871w1n012b-ap4441283_01_l.jpg
 

AndyLisson1987

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Location
Ontario, Canada
Thanks Rick. So step one, plug the oven in and set to bake, correct? And then below is a picture of my multimeter. Any idea what setting I should be on and what terminals I should touch the black and red wires to? Apologies if these are dumb questions but I’m pretty green on this subject. Thanks again!

image.jpg
 

rickgburton

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I got you covered this time but learn how to use your meter. It comes in handy for a lot of things. DC Volts is voltage from a battery. Electronic symbol=
DC.jpg
AC Volts is the voltage in your home. Electronic symbol=
AC.jpg


Turn your meter one click clockwise to 750V. When measuring VAC, red and black doesn't matter. Take the back panel off so you can access the relay board and plug in the range . Set it to bake, any temperature.
LG Range.jpg


Touch one meter lead to BAKE and touch the other to L2 then BAKE. Your meter should indicate 220 VAC for both measurements.
LG relay board.jpg
 

AndyLisson1987

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Ontario, Canada
Rick, I can’t begin to thank you enough. You made that testing idiot proof for me. Both readings tested at 240V. I assume since both tested at 240, that means it is the relay board that needs to be replaced?
 

rickgburton

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that means it is the relay board that needs to be replaced?
No, that tells you there's 240V going out to the bake element. So the bake element turns on?
I also tested the bake (and broil) elements
Recheck the bake element again. Check for the 240V across the bake element terminals in bake mode.
 

AndyLisson1987

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Location
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So when I check the bake element for voltage, I get a reading of 0. Sorry, when I tested them earlier, I tested ohms for continuity.

So to summarize, broil at about 17 ohms and 240V. Bake at 17 ohms and 0V. However, both relay board tests you had me test tested at 240V. Any ideas?
 

rickgburton

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So when I check the bake element for voltage, I get a reading of 0.
OK, so when you set it to bake about 350° you have 0V @ the bake element. Is that correct? The wire from the relay board on the bake terminal goes to one side of the bake element and the wire on the other bake terminal on the relay board goes to the other side of the bake element. So you're saying you have 240 V at the relay board but not the bake element? Then one of the two wires must be broken .
 

AndyLisson1987

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Yes that is exactly correct. I will triple check tonight and then order some new wires. Any idea where to order them or what they would be called?
 

rickgburton

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You don't need to replace any wires. You need to find the break in the wire and repair it. I have a funny feeling someone is missing something and it might be me. I don't have a wiring diagram for that machine. I'm going by a wiring diagram for a similar machine and experience. LG usually keeps the same wiring layout across models but it may have changed with your model so do this; Unplug the range and physically trace the wires from the relay board to the bake element. Lets make sure it's the same wires. If the wires are correct, all you need to do is check those wires, one at a time, for continuity to find the broken one. I'll make you a diagram:
wires.jpg
 

AndyLisson1987

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Okay Rick, I tested everything again. Your diagram was helpful, slight change in that A connected to D and B connected to C. Running all the tests again and noticed the bake to bake test was getting zero V. However, the bake to L2 test was getting 242V. I ran every test I could think of and have posted the results below.
 

rickgburton

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rickgburton

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This might help for future reference:
 

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  • How to use Test Equipment.pdf
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AndyLisson1987

Premium Member
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Mar 13, 2021
Messages
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Location
Ontario, Canada
Installed the relay board, tested this morning and works like a charm. My wife has been baking all day and zero issues. She is very happy. Thanks Rick for all of your advice!! Much appreciated!!
 
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