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Author Topic: Help modifying LG washer for project with kids (WT7200CW)  (Read 1132 times)

Offline Sykoken

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Help modifying LG washer for project with kids (WT7200CW)
« on: August 07, 2021, 02:25:10 PM »

Hey guys! I just signed up to this forum after downloading the service manual for the washer I'm working with.

Unfortunately I wasn't able to get the washer to do what I needed it to do via the control board/service mode and ended up blowing the board in the process anyway.

I know this isn't exactly a repair but I'm hoping the pros here can help me still.

What I'm trying to accomplish is hard wiring the motor to spin at full RPM so I can use it as a centrifuge. Its a direct drive motor with only 4 wires (red, blue, yellow, green). I couldn't find a run capacitor anywhere near the motor for the life of me, but I'm wondering if it was built into the board.

So far this is what I've discovered.

4 wires are
Red - power?
Blue - common?
Yellow - signal (130v top spin speed)
Green - ground

I tried connecting the red and yellow wires together, because while I was testing the voltages during the spin cycle the red was constantly at 120v and the yellow ramped up from 0 to 130v. I was hoping I could send power to the motor and initiate a spin at the 120v RPM via the signal wire.

All I got was a hum from the motor.

So what I'm guessing is the run capacitors were built into the board, which is now shot.

My question I suppose is, can I wire in a different run capacitor directly to the hot wire, then to the motor? I've seen a bunch of YouTube videos doing this, but not with an LG direct drive motor. It seems simple but I'm stuck.

Any help is much appreciated!

Thanks in advance

Ken

Offline Sykoken

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #1 on: August 10, 2021, 02:20:36 PM »
Any ideas? I'm willing to try anything haha 😄

Offline 100 td

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #2 on: August 11, 2021, 05:00:28 AM »
I don't know your washer, but since you have the service manual I expect you be able to ascertain if this machine is a variable speed drive motor (most likely theses days depending on how old it is and type of washer), if it is, I expect you'll need a controller to run it.

Offline Sykoken

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #3 on: August 11, 2021, 08:23:03 AM »
Thank you for the info!!! So are you saying this may not even have a run or start capacitor? I just need a voltage controller to ramp from 0-130v? I found something on Amazon I think would work, what do you think?

https://www.amazon.com/dp/B07CB4LKB3/ref=cm_sw_r_cp_apa_glt_fabc_8DC1S7JMNB54NK27VSVX

I don't know your washer, but since you have the service manual I expect you be able to ascertain if this machine is a variable speed drive motor (most likely theses days depending on how old it is and type of washer), if it is, I expect you'll need a controller to run it.

Offline Sykoken

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #4 on: August 11, 2021, 08:27:46 AM »
Here is the service manual, if anyone can help decipher it. I uploaded it to my Samsung cloud because it was too large to upload directly.

https://linksharing.samsungcloud.com/qqTWZu7YxNIR

Offline 100 td

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #5 on: August 11, 2021, 08:21:13 PM »
You need a VFD or 3 phase supply(possibly voltage and/or frequency limited depending on motor specification)

Offline 100 td

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #6 on: August 11, 2021, 09:09:41 PM »
Remember we are talking lethal voltages here, not ideal for untrained/DIY folks or kids. There are no second chances.

Offline Sykoken

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #7 on: August 12, 2021, 10:28:45 AM »
Thanks for the follow up info! I'm looking into this now.

I should add that I'm definitely not a novice when it comes to working with power. Also the students aren't the ones using the centrifuge, I will be, however it is a component to the project we're working on.

Would you be available via direct message to help out a bit more?

Remember we are talking lethal voltages here, not ideal for untrained/DIY folks or kids. There are no second chances.

Offline 100 td

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #8 on: August 12, 2021, 07:41:11 PM »
...
« Last Edit: August 12, 2021, 07:46:32 PM by 100 td »

Offline 100 td

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #9 on: August 12, 2021, 07:45:35 PM »
 
Quote from: Sykoken
I'm definitely not a novice when it comes to working with power.
This tells me you aren't licensed
Quote from: Sykoken

Also the students aren't the ones using the centrifuge
This tells me you are putting other folks at risk.
DANGER
Get it sorted by a licensed electrician to code.

Offline tcarmen

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Re: Help modifying LG washer for project with kids (WT7200CW)
« Reply #10 on: August 17, 2021, 08:05:22 PM »
It's a variable speed/variable frequency 3 phase motor controlled by an inverter on the board. There is no start or run winding.

There is no "hack" I'm aware of to make the motor run at full speed, and even if there was you could easily kill people because the various support points for the tub are not rated for Ludicrous Speed, and it's entirely likely that the entire thing would self destruct sending chunks of metal and plastic everywhere, not to mention a giant spinning stainless steel tub that will fly off and destroy or kill whatever it hits.

There's a youtube video of this done on a different brand/model and all I can say is that I wouldn't want to be anywhere near it.

In case there's any question, this falls squarely into "It's a really bad idea and you should not do it" territory.