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TROUBLESHOOTING
2. SYSTEM CIRCUIT
A. VFD DISPLAY
No VFD display.
Is 5V obtained at IC701 pin#1?
YES
Is -26V obtained at IC701
pin#16~17?
YES
Oscillation at IC701 pin #2?
YES
Is -22V, -18V obtained at F
F+?
YES
Specific GRID/SEG doesn't
function.
YES
GRID output at PORT of
IC701?
YES
SEG output at PORT of IC701?
NO
Check D701.
NO
Check POWER circuit at -26V.
NO
Check C704, IC701.
NO
Check POWER circuit at F-, F+.
NO
Check IC 701 pin #18~27.
NO
Check IC 701 pin #28~43.
Exchange IC601.
6
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