73
TROUBLESHOOTING
SYSTEM CIRCUIT
No VFD display.
Is 5V obtained at IC701 pin#13?
Is -24V obtained at IC701
pin#30?
Oscillation at IC701 pin #8?
Is -24V, -20V obtained at
F-, F+?
Specific GRID/SEG doesn’t
function.
Check D721.
Check POWER circuit at -24V.
Check IC701.
Check IC 701 pin #31~42.
Check IC 701 pin #14~29.
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
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Summary of Contents for DR-C912B
Page 13: ...11 INSTRUMENT DISASSEMBLY All manuals and user guides at all guides com...
Page 39: ...37 EXPLODED VIEW 6 3 EXPLODED VIEW OF FL ASS Y All manuals and user guides at all guides com...
Page 44: ...42 WAVEFORMS VIDEO WAVEFORMS 480 4 6 20 34 All manuals and user guides at all guides com...
Page 114: ...NORMAL AUDIO BLOCK DIAGRAM 112 BLOCK DIAGRAM All manuals and user guides at all guides com...
Page 117: ...AMP BLOCK DIAGRAM 115 BLOCK DIAGRAM All manuals and user guides at all guides com...
