Quick check PWM waveform
After power is turned on, we could measure 7 channels PWM waveform
at four connectors easily. Any abnormal of PWM waveform may be
caused by PWM IC or power output section (MOSFETs & drive ICs).
RED PIN
PWM at two
end pins on
3connectors
7 channels
(CN521)analog
audio signal.
PWM waveform 4.2V p-p
Master Clock 5V p-pAMP -B
‘AMP –B’+4.2V
FL----FR
SL----SR
SBL--SBR
C
FW323
PIN 4
820 Ohm-
Without AC power the resistance
form ‘AMP_ -B’ to each of 7 CHs.
PWM pin should be 820 Ohms. If
is too low, the drive IC at the next
power amp stage is defective.
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