LG WM3987H Series Service Manual page 23

If it still has severe vibration and noise, regulate a specific spin speed that generates excessive vibration and
noise as follows:
1) Put an unbalance part (rubber) inside of the drum.
2) Start the QC test mode (Refer to section 7-2).
3) Press Delay Wash button, then '
4) Press the Spin Speed button repeatedly to select Extra High.
5) Press the Quick Cycle button, the spin speed is displayed.
6) Press the Start/Pause button.
7) Press the Beeper button repeatedly to set spin speed (600, 800, 1000, 1200 rpm) and check if there is vibration
and noise.
8) If there is no vibration and noise, increase the spin speed by pressing Beeper button.
9) If there is vibration and noise, rotate the Cycle selector knob clockwise to reduce the Spin Speed (reduce by 50
and 100 rpm). In case of 600 rpm, it can not reduce the spin speed.
10) If vibration and noise are reduced, press the Quick Cycle button to store (2 beep sounds).
* If you want to return to factory default spin speed setting, repeat above steps except step 9).
' is displayed.
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