48
FLOW CHART NO.12 (704-6K2-A618 IO PCB ASS'Y, 704-6K2-A617 : MAIN PCB ASS'Y)
Audio is not output from the Master output.
Are the PH(6pin:CN1), FFC(24pin:CN102), and
FFC(20pin:CN801) correctly connected?
YES
• Set the channel input source switch to "LINE"
• Set the CROSS FADER CONTOUR to "THRU"
• Set the input level volume to "12:00"
• Set the Cannel FADER to "MAX".
• Set the master level volume to "14:30".
Are audio signals output to 18pin(Lch), 15pin(Rch) of U755
when an audio signal of 1kHz 0dBV is input externally to the
LINE input?
Are the audio signals outputted to 7 pin(Lch), 1 pin(Rch) of
U507?
Are the audio signals outputted to 7 pin(Lch), 1 pin(Rch) of
U508?
Check surrounding circuit of JK504, JK505 from 1 pin(Rch), 7
pin(Lch) of U508, and replace any faulty parts.
Is base terminal of Q42(MUTE control signal) +3.3V, and has
been base terminal of Q518~Q521(MUTE drive signal) L
(-12V)?
YES
YES
YES
YES
NO
Connect the connector cable and FFCs correctly.
NO
Check surrounding circuit of U755, and service it if defective.
When the surrounding circuit is correct, replace U755.
NO
Check surrounding circuit of U507, and service it if defective.
When the surrounding circuit is correct, replace U507.
NO
Check surrounding circuit of U508, and service it if defective.
When the surrounding circuit is correct, replace U508.
NO
Check surrounding circuit of Q42, Q518~Q521 and replace
any faulty parts.
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