Daewoo SD-8100, Service Manual

Page: 6 / 63

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