Read Sharp VC-MH742HM (serv.man19) Service Manual online
50
VC-M332HM
VC-MH742HM
VC-MH742HM
FLOW CHART NO.29 GAMMA TROUBLESHOOTING
NO
NO
NO
YES
YES
Is the luminance signal output to
the pin(7) of slice, impedance
conversion circuit IC4401?
Is the luminance signal output to
the GAMMA input Q211 emitter?
Is the luminance signal output to
the pin(1) of impedance conversion
circuit IC4401?
NO
YES
Is the luminance signal output to the
pin(5) of slice, low impedance part
amplification IC4403?
NO
YES
Is the luminance signal output to the
pin(7) of impedance conversion,
slice circuit IC4402?
NO
YES
Is the video signal input into the
pin(1) of video level adjusting circuit
IC4403?
NO
YES
Is the video signal input into the
pin(3) ofluminance signal selection
circuit IC4407?
NO
NO
YES
Is the video signal output to the
pin(7) of luminance signal selection
circuit IC4407?
YES
The GAMMA corrrection circuit does no function.
Check the line between the pin(52)
of IC201 and Q211.
Check the line between the pin(1)
of IC211 and Q211 emitter.
Check the line between the pin(1)
of IC4401 and the pin(7) of IC4401.
Check the line between the pin(1)
of IC4401 and the pin(5) of IC4403.
Check the line between the pin(5)
of IC4403 and the pin(7) of IC4402.
Check the peripheral circuit of
Q4405, Q4406, R4414, R4415,
R4416, R4431 and R4433.
Check the video level adjustment
(IC4403) circuit and video amplifi-
cation(IC4402) circuit.
Check or replace the periphery of
IC4407.
Is the pin(2) of IC4407 in "H" level
state?
Check the GAMMA(H) line.
Check the line between the pin(2) of
IC4407 and the pin(30) of IC801.
FLOW CHART NO.30 DECODER TROUBLESHOOTING (VC-MH742HM)
<Hi-Fi Audio Double scart>
MODE
SIG.
DECODER CIRCUIT
SELECT
INPUT SIGNAL
FLOW
SIG.
FLOW
INPUT
(switch)
OUTPUT
OUTPUT SIGNAL
(A)
Pin47 of IC701(Y/C video output)
E2(L2) video input
→
pin19
pin18
pin20
→
E1(L1) video output
21PIN CONNECTOR
(B)
→
(A)
Pin20 of IC6401(Audio output L-ch)
E2(L2) audio input(L-ch)
→
pin36
pin1
pin35
→
E1(L1) audio output(L-ch)
21PIN CONNECTOR
(B)
→
(A)
Pin19 of IC6401(Audio output R-ch)
E2(L2) audio input(R-ch)
→
pin33
pin3
pin32
→
E1(L1) audio output(R-ch)
21PIN CONNECTOR
(B)
→
(A)
Tuner video output
E1(L1) video input
Pin47 of IC701(Y/C video output)
→
pin16
pin14
pin19
pin23
→
E2(L2) video output
21PIN CONNECTOR
(B)
→
(C)
→
(A)
MPX. output(L-ch)
E1(L1) audio input(L-ch)
Pin20 of IC6401(Audio output L-ch)
→
pin9
pin5
pin36
pin29
→
E2(L2) audio output(L-ch)
21PIN CONNECTOR
(B)
→
(C)
→
(A)
MPX. output(R-ch)
E1(L ) audio input(R-ch)
Pin19 of IC6401(Audio output R-ch)
→
pin11
pin7
pin33
pin28
→
E2(L2) audio output(R-ch)
21PIN CONNECTOR
(B)
→
(C)
→
(A)
E2(L2) video input
E1(L1) video input
Tuner video output
→
pin18
pin14
pin16
pin21
→
Pin31 of IC201
Y/C video input
(Tuner/Aux. input)
(B)
→
(C)
→
(A)
E2(L2) audio input(L-ch)
E1(L1) audio input(L-ch)
MPX. output(L-ch)
→
pin1
pin5
pin9
pin31
→
Pin15 of IC6651
Audio input(L-ch)
(B)
→
(C)
→
(A)
E2(L2) audio input(R-ch)
E1(L1) audio input(R-ch)
MPX. output(R-ch)
→
pin3
pin7
pin11
pin30
→
Pin10of IC6651
Audio input(R-ch)
(B)
→
(C)
→
NO
NO
NO
YES
YES
YES
Check STBY 5V line.
Check STBY 11V line.
Check line between pins(25), (26)
of IC2501 and pins(27), (28) of
IC701.
Is voltage 5V applied to the video
section power terminal at pins(15),
(17) of IC2501?
Is voltage 11V applied to the
audio section power terminal at
pins(8), (10) of IC2501?
Check signal line from video and
audio function logic table as shown
below.
Not output from 21pin connector in video and audio signal.
Is there SDA and SCL signal
applied to pins(25) and (26) of
IC2501?
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