3-5
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ONE POINT REPAIR GUIDE
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 (VFD801)
3-1-1. Solution
Replace TOP board.
3-1-2. How to troubleshoot (Countermeasure)
1) Check if VFD_12V, DVCC_3.3V and DV_5V are output from MAIN to VFD via the TOP board.
2) Check if the IC501 outputs VFD_CLK, VFD_STB, and VFD_DO to the TOP board(CNT804 pin6~8).
3) Check if the VFD grid current amplifier circuit on the TOP board.
Check the drive signal to the transistor’s(CNT804 pin6~8) base.
If the control signals from VFD (SW) isn’t output, replace VFD with a new one.
VFD heat rays is RED : DVCC_5V(IC201 check) Voltage will be high than 5.5 V.
No VFD : VH(VFD801 pin27) will be not supply about 30 V.
No VFD : VFD 12 V will be not supply (Check Q205).
3-1-3. Service hint (Any picture / Remark)
about
12Vp- p
< CN804 >
CN804 Base
< Waveform of the grid current driver>
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