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9.9.
TROUBLESHOOTING HINTS
CM Advance Section
HOW TO CONFIRM IF CM ADVANCE CIRCUIT IS WORKING.
Record any broadcast including commercial over 30 seconds. Then, as recording continues, proceed with all troubleshooting
of CM Advance Circuit.
START
Confirm if control pulse at Pin 5 of P1541 on A/C Head unit changes
as shown in Fig.1 when the black portion(No video & No audio) at
both the beginning and end of a commercial appears on TV.
OK
CM Advance circuit works OK.
Control Pulse at Pin 5 of P1541 on AC Head Unit
33.3msec
approx. 4V
approx. 1.5V
60%
40%
(DUTY)
NG
Perform the "TROUBLESHOOTING OF CM ADVANCE."
33.3msec
approx.4V
approx. 1.5V
27.5%
72.5%
(DUTY)
Fig.1
TROUBLESHOOTING OF CM ADVANCE
Confirmation of Audio signal
Confirm if the signal at TP3801
Check IC3801 and parts
becomes LOW when the black
NG
surrounding Pin 3, 4, 5, 7 and 8
portion (no audio) at both the
of IC3801.Replace if necessary.
beginning and end of a
commercial appears on TV.
OK
Confirm if the signal at Pin 44 of
Check signal line between Pin 44
IC6001 becomes LOW when the
NG
of IC6001 and Pin 11 of IC3801.
black portion (no audio) at both
he beginning and end of a
commercial appears on TV.
OK
Confirmation of E/V Mask pulse
Is E/V Mask pulse at TP3803
Is there the video signal at Pin
NG
correct as shown in Fig.2?
33 of IC3801?
NG
OK
Check signal line between Pin
25 of IC3001 and Pin 33 of
IC3801.
Is E/V Mask pulse at Pin 2 of
Check signal line between
NG
IC6001 correct as shown in
Pin2 of IC6001 and Pin 13 of
Fig.2?
IC3801.
OK
TP3805
(V pulse)
approx. 5msec approx. 12.5msec
TP3803
/Pin 2 of IC6001
(E/V Mask pulse)
79
Confirmation of Video signal
Confirm if the signal at TP3802
Check IC3801 and parts
becomes LOW when the black
surrounding Pin 28 and 30 of
NG
portion (no video) at both the
IC3801.Replace if necessary.
beginning and end of a
commercial appears on TV.
OK
Confirm if the signal at Pin 43 of
Check signal line between Pin 43
IC6001 becomes LOW when the
of IC6001 and Pin 25 of IC3801.
NG
black portion (no video) at both
the beginning and end of a
commercial appears on TV.
OK
Check IC6001.
Replace if necessary.
Check IC3801 and parts
OK
surrounding Pin 21, 22, 31, 32,
and 33 of IC3801.Replace if
necessary.
approx.5V
approx.0V
approx.5V
approx.0V
V rate
Fig.2
PV-9661 / PV-9662
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