39
VC-A415U/H815U
VC-H817U/H818U
7.
TR
OUBLESHOO
TING
FLOW CHART NO.1
No power
The fuse blows out even when it is
replaced with new one.
See
FLOW CHART NO.2
<Fuse blown out.>.
YES
YES
YES
YES
NO
NO
NO
NO
NO
Is the fuse good?
Is the normal state restored when
once unplugged power cord is
plugged again after several
seconds?
Check for leak or short-circuiting
of primary circuit part.
(L901, D901~904, T901, C906,
R904, Q901~902, etc.)
Are AT 5V voltage line normal?
Are AT 44V, AT 23V, AT 12V,
AT –24V and filament voltage lines
normal?
Check each rectifier circuits and
short-circuit of secondary circuit.
Is "H" level applied at pin(1) of
IC701?
Check the power failure circuit.
(Q705)
FLOW CHART NO.3
When the output voltage fluctuates.
Check whether the secondary side
photocoupler circuit operates
normally.
Check the circuit and replace parts.
(IC901, IC903, etc.)
NO
YES
Check whether the primary side
photocoupler output control
functions normally.
Check the circuit and replace parts.
(IC901, IC903, Q902, T901, etc.)
NO
YES
Replace IC901.
FLOW CHART NO.2
Fuse blown out.
Case (1)
Case (2)
Check for leak or short-circuiting of
primary circuit part.
(L901, D901~904, T901, C906,
R904, Q901~902, etc.)
Check for short-circuiting of
rectifying diode and circuit in each
rectifying circuit of secondary circuit.
(D921~928)
FLOW CHART NO.4
When buzz is heard from the vicinity of power circuit.
Check for short-circuiting of circuit and rectifying diode of each rectifying circuit of secondary
circuit and check for failure of shunt regulator circuit. (D921~928, IC903, C932, C933)
FLOW CHART NO.5
The flourescent display tube fails light up.
Is the supply voltage of 5V feed to
pin(8) of IC801?
Check AT 5V line.
Check AT –24V line.
Is the supply voltage of –24V
feed to pin(1) of IC801?
Are grid and segment signals
supplied to the indication tube
(DG801) from the indication
tube driver IC (IC801)?
Replace IC801.
Is supply filament voltage feed
between pin(1)/(2) and (31)/(32)
of the flourescent display tube?
Check power circuit and D952.
Check the periphery of fluorescent
indication tube and main block.
Check that the fluorescent indication
tube is free from damages such as
crack.
YES
YES
YES
YES
NO
NO
NO
Is it possible to confirm signals
FIP CS, FIP OE, FIP DATA, and
FIP CLK on the pins(2), (3), (5) and
(6) of IC801?
Check signal line between IC701
and IC801.
YES
NO
NO
NO
Содержание VC-A415U
Страница 48: ...VC A415U H815U VC H817U H818U VC A415U H815U VC H817U H818U 50 51 8 BLOCK DIAGRAM SYSTEM SERVO BLOCK DIAGRAM ...
Страница 51: ...56 VC A415U H815U VC H817U H818U POWER CIRCUIT BLOCK DIAGRAM ...
Страница 61: ...72 VC A415U H815U VC H817U H818U M E M O ...
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