LG CJS98F - Vfd Is Not Displayed When Power on the Set

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ONE POINT REPAIR GUIDE
10. VFD IS NOT DISPLAYED WHEN POWER ON THE SET
When power on the set, any icons or characters on VFD are not displayed.
10-1. VFD (VFD301)
10-1-1. Solution
Please check and replace VFD301 on FRONT board.
10-1-2. How to troubleshoot (Countermeasure)
1) Check if VH, F+ and F-, DVCC_3.3V are output from SMPS to VFD via the MAIN board.
2) Check if the IC501 outputs VFD_CLK, VFD_STB, and VFD_DO to the FRONT board.
3) Check if the VH, FRONT_12V, SW on the FRONT board.
 If the VH from VFD(DGND, VDD) isn’t output, replace VFD with a new one.
10-1-3. Service hint (Any picture/ Remark)
< FRONT circuit > < FRONT circuit >
VFD_STB,
VFD_STB,
VFD_CLK,
VFD_CLK,
VFD_DO
VFD_DO