Vfd Is Not Displayed When Power On The Set - LG CMS9540F Service Manual

3. VFD IS NOT DISPLAYED WHEN POWER ON THE SET

When power on the set, any icons or characters on VFD are not displayed.
3-1. VFD (DIG300)
3-1-1. Solution
Please check and replace DIG300 on FRONT board.
3-1-2. How to troubleshoot (Countermeasure)
1) Check if 39V, FL+ and FL-are output from SMPS to VFD via the main board.
2) Check if the IC101 outputs VFD_RST, VFD_CLK, VFD_STB, and VFD_STB to the front board.
3) Check if the VFD grid current amplifier circuit (Q301, Q303) on the front board.
Check the drive signal to the transistor's base.
If the control signals from VFD (DGND_2, VH, VDD) isn't output, replace VFD with a new one.
If the transistor doesn't work, replace it.
3-1-3. Service hint (Any picture / Remark)
ONE POINT REPAIR GUIDE
< MAIN board top view >
3-5