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LRE3083ST LG Range - Bake element no good?

Patrick1

Premium Member
Joined
Dec 1, 2021
Messages
8
Location
New York
Model Number
LRE3083ST
Brand
LG
Age
6-10 years
I have an LG LRE3083ST electric oven that's not getting to preheat temp, seems like the bottom bake element is the problem. It's located under the cavity floor and out of sight so I can't see that it's NOT working but that surface doesn't get very hot - so the assumption is that it is not working. FYI, the broil element works just fine.

I've checked voltage at the receptacle and across both bake element terminals, while on and in "bake" mode, and there's no problem there - it's getting 120V at both terminals. Also, checked the bake element for continuity and that was okay too - so can the bake element have good continuity and still be no good?

Once I get voltage at the element terminals it should heat up, right? It's been my experience that continuity usually implies that the problem lies elsewhere but in this case I'm a bit confused as to what to do next.
Appreciate any advice you can offer, thank you.
 

Dan O.

Appliance Tech
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Oct 9, 2004
Messages
6,324
Location
Ontario, Canada
Patrick1 said:
I've checked voltage at the receptacle and across both bake element terminals, while on and in "bake" mode, and there's no problem there - it's getting 120V at both terminals.

You can't check for power like that. Remove at least one wire from the element and check for 240 volts between the two wires going to the element.

You can also test the element for continuity (with at least one wire disconnected). If the element is defective it will measure infinite resistance.

These links are pertinent to your message. They were supplied by this message author. Please view them.


LINK > Appliance411 FAQ : How do I test for continuity?

LINK > LG LRE3083ST Bake Element



Dan O.
 

Patrick1

Premium Member
Joined
Dec 1, 2021
Messages
8
Location
New York
I should clarify that when I checked for voltage at the bake element terminals I checked the disconnected wires and not the element itself - and there was 120V at each wire. But you're saying I should check for 240V across both wires, with at least one wire disconnected from the bake element, right?

As for the continuity test, it was done with no wires attached and directly to the element ends. It showed that it has continuity, can the bake element still be no good or is that a definitive test that it's good?
Thanks again.
 

Dan O.

Appliance Tech
Staff member
Joined
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Messages
6,324
Location
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If you test for 120 volts with the element still attached you may be reading the same 120 volts on each side of the element.

Yes, at least one of the wires needs to be removed first. However the proper test is checking for a full 240 volts going to the element wires when turned on. That is what the element operates on, 240 volts.

it has continuity. can the bake element still be no good or is that a definitive test that it's good?

IF the element was responsible for NO heat, it would have to have infinite resistance.


Either your voltage readings are wrong or your continuity test is wrong.

Dan O.
 

Patrick1

Premium Member
Joined
Dec 1, 2021
Messages
8
Location
New York
Thanks Dan O! Okay, went back and performed the voltage test the correct way this time - I hope. There is NOT 240V across the wires to the bake element. Separately, one has 120V, the other has 0V and across both wires they read 0V, is that right? Bake element, with both wires removed, has continuity and read 16.4 ohms of resistance, is that within normal range? Also checked the heat sensor and it checked at 1080 ohms. Thermal fuse had continuity as well. Did a thorough search for loose, burned, frayed wires or loose connectors and found nothing. Is my next stop the oven relay board and how would I test that?
 

Dan O.

Appliance Tech
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Joined
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Messages
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Is my next stop the oven relay board

That would be my assumption.

This link is pertinent to your message. It is supplied by this message author.

LINK > LG LRE3083ST Relay PCB Assembly EBR74164805 / AP5785752



and how would I test that?

I do not know that. It might be possible to determine the bake element connection on the relay board and then try to test if the board is powering that circuit when the bake element should be on?


Dan O.
 

Patrick1

Premium Member
Joined
Dec 1, 2021
Messages
8
Location
New York
I'm going to try that today but I'm not sure that it would be a definitive test. I assume the main control board sends a signal to the relay board when a function, such as "bake", is requested. If there's a breakdown in that process, how do I tell if it's the relay board that is not doing it's job by sending the correct voltage to the element OR that it's just not getting the "message" from the main control board? Let me ask this first, am I assuming the proper chain of events between control board and relay board - is that the way it works? Second, is there some way to test THAT process?
Something tells me the only way to find out is to start replacing these parts and the relay board is the likely culprit, right? Obviously not my first choice but unless someone has a way to test these components, it may be my only choice. Well, that or a new oven I guess.
 

Dan O.

Appliance Tech
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Messages
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assuming the proper chain of events between control board and relay board - is that the way it works?

Such a function usually works like that. I can't say for certain on that exact model.

Second, is there some way to test THAT process?

Maybe but I am not familiar with that exact model. Most appliances have a 'tech sheet' with its wiring diagram that often describes various functions and test procedures. Look for the one in the range.

the relay board is the likely culprit, right?

It's the part that actually does the power switching and has mechanical relays that frequently fail from wear and tear and from power fluctuations.

Something tells me the only way to find out is to start replacing these parts

If you can determine the relay involved, it might be possible to test if its contact stays closed even when unpowered. That would preclude the control being responsible for activating it, thereby isolating the relay board itself to being the likely cause.

JMO

Dan O.
 

Patrick1

Premium Member
Joined
Dec 1, 2021
Messages
8
Location
New York
Thanks for the info and suggestions. I referred to the tech spec sheet already and it wasn't much help with diagnosis. I'm trying to operate with a scalpel and they use the sledgehammer approach just replacing parts sequentially until they find the problem. I was able to isolate the bake switch on the relay board and it has 120V going in but nothing comes out when the "bake" function is engaged. I checked all the wires from the control board to the relay board just in case it was something silly like a bad wire, but they are all fine. Since everything else on that relay board works I'm going to try and change the bake relay switch rather than buy a whole new board. If that doesn't fix the problem then it has to be the main control board but at least I'm not out $150, or more, for the relay board.

If anyone has any experience changing out one of these switches on a circuit board, I'd appreciate any tips or suggestions. Also, the switch is a "Song Chuan 888HN-1AC-F-C" and it's not very easy to find outside of China. Does anyone know of cross reference part that can be used instead?

It's the switch just to the right of the pink(?) connector:

IMG_20221112_122621307_HDR.jpg
 

Dan O.

Appliance Tech
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Messages
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Location
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Sorry but I've never done electronics repair. I have no idea where you can get replacement components for it.


Dan O.
 

Patrick1

Premium Member
Joined
Dec 1, 2021
Messages
8
Location
New York
First time for me too. I'll probably end up ordering it from China, not many other options available so far. Fortunately, the oven is not DOA so, for now, I have the luxury of pushing the repair for 2-3 weeks until the part arrives. Thanks again for your help, I'll let you know how this turns out.
 
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