Harman Kardon FL8550 Service Manual page 31

FL8550
The bottom hold has had two time constant of long and short, after than the RFI signal inverted. The
short time constant of bottom hold is generated shorter than 0.1m sec of disc mirror defect, and long time
constant is generated by previous mirror level. Mirror defect detection signals are generated by
differentiation on Capacitor Coupling, and then transfer level.
7. EFM COMPARATOR
The EFM Comparator converts a RF signal into a binary signal. A processing of disc production is
occurred disproportion because of modification of disc. That is not reduced by only AC coupling. The
reference voltage of EFM comparator is controlled utilizing the fact that the generation-probability 1, 0 is
50% (duty) in the binary EFM signal.
8. APC (AUTOMATIC POWER CONTROL) CIRCUIT
As the Laser diode has had large negative temperature characteristic when it does something for
regularly supply current on laser diode. Therefore, the output on processing monitor photo diode must be
controlled current for getting regularly output power.
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