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Author Topic: LG Dishwasher lost all power - no error codes, no LEDs. Main PCB? Help identify?  (Read 23920 times)

Offline Justin311

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Hello,

I have a roughly 2 year old LG d/w (LDF7932) which just up and lost all power right after running a cycle.  I have 120V coming in but pressing the power button yeilds NOTHING (or any other button), no LEDs will power on.  The diagnosis flowchart states that after checking the circuit breaker, check "The power switch or the circuit is OK?  Check Controller (Power Circuit)."

I have pulled the front of the d/w off and the PCBs are easily available, however I cannot find any diagrams labeling what is what.  The diagram shows 3 PCBs - Main, Cycle and Option/Display.  I am assuming the largest one just below the button "bar" is the main PCB.

I need to determine the correct failed part so that LG will send me a replacement.  But the diagrams are not really helping me and the flowchart doesn't tell me how/what to check for "controller (power circuit)".

Can anybody assist me?

Offline Justin311

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I should note that the largest board has a PN stamped into it as follows: eax37902902.  Also has some other characters below that.  I am trying to determine if this is the main PCB, and also how to test it for incoming power.  I can post pictures if it helps....

Offline bigbuck

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found some info. @ lg database, hopefully it will help

Offline bigbuck

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the wire diagram is to large, trying to make it smaller to send
« Last Edit: December 27, 2011, 06:47:14 PM by bigbuck »

Offline AJ

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Let see how this works...

Here is the wiring diagram.


Offline bigbuck

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check the door switch, have replaced a few for this problem.

Offline Justin311

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Thanks for the help guys...I have that diagram but have been unable to identify those plugs on the PCB...I suppose I need to post a picture of it.

As far as the diagnostics system I can't use it - I've tried to press the 3 buttons but the display never powers up.

Bigbuck, as far as the door switch I don't think that can be it.  This particular model has all buttons on the top surface of the door, you actually open the door slightly to press the buttons, once you have powered it on and set your cycle then you close it.  So the door switch couldn't cause it not to power up, would it?  Or am I misunderstanding?

Offline bigbuck

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 check power @ filter , if no power from filter to main board, replace filter # 6201ec1006l. if power to main control, but no power out, replaced main control # ebr381006l.

Offline Justin311

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check power @ filter , if no power from filter to main board, replace filter # 6201ec1006l. if power to main control, but no power out, replaced main control # ebr381006l.

Again, I appreciate the help.  I'm hoping for some hand-holding here as I am far from an electrician.  Studying the diagram I see that plug WH3 is power IN to the filter and plug RD3 is power OUT of the filter.  I am not sure where the filter is located...however....I found a plug labeled "RD3" on the main PCB.  As pictured below (and zoomed in) RD3 has 3 wires coming in (Blue/Lt Blue/White) and these wires do NOT have power at them.  The three wires disappear into the wiring loom and everything is taped up and in a plastic sheath as it passes under the door. 

Therefore I am assuming the power is disrupted BEFORE the filter (hopefully at).  Can you help me located WH3 plug (filter power IN)?  Or if I am on the wrong path here point me in the right one please?   Thanks again for your help! :)




Offline Justin311

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I should add I have a "drawing" of the filter assembly based off the PN you gave me (from the service manual posted), I believe, labeled A-160 below.  However, it really doesn't help me much as it looks like an ambiguous box :(


Offline Justin311

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Found it!  And indeed the power filter has 120V coming in and nothing coming out.  The weirdest part is it has a small fuse (glass cylinder) that is soldered to the board and then epoxy'd over.  I guess its a fail safe but still odd, why isn't it replaceable.  If they dont make me send it back (still under parts warranty) I'm going to dissect it and see if it blew.

Ordering the part from LG now....keeping fingers crossed!

Offline bigbuck

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way to go, nice diagrams!!! O0

Offline haole07

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check power @ filter , if no power from filter to main board, replace filter # 6201ec1006l. if power to main control, but no power out, replaced main control # ebr381006l.

I have similar issue with my  LDF 7810 but output from filter is reading 60 volts (Probing Ground / Hot). 

When I probe Hot / Neutral I get 120 volts is this normal?

Offline rpaull

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check power @ filter , if no power from filter to main board, replace filter # 6201ec1006l. if power to main control, but no power out, replaced main control # ebr381006l.

I know that this post is quite old, and it has been rather helpful in trying to diagnose my problem but I'm not getting any farther. The display will not come on.
I too have a LG LDF7932st with very similar symptoms however I do have power coming out of the noise filter, the door switch contacts are working properly and I have just replaced the main PC board - and still no luck. I've run the system test and all I get is the 2 front panel display lights flashing together and a "Ding Dong","Ding Dong","Ding Dong" 3 consecutive times. While the front display continue to flash, I can press each button and each responds with a "Ding Dong", so I believe I can safely say the buttons work.
what would you suggest I check next or replace next?

Thanks for your help!

Offline rpaull

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 :tickedoff: HELLO?? Is there anybody out there??  :tickedoff: