Harman Kardon FL8550 Service Manual page 33

FL8550
While the focus search is operating, the FS4 switch is ON and then focus error signal is isolated,
accordingly it is outputted by FSEO Pin (Pin48). When the FS2 switch is ON, the focus servo Loop is on
and then focus error is outputted through the focus servo Loop.
2. TRACKING AND SLED SERVO LOOP
The capacitor across RTG (Pin16) and TGSW (Pin15) reduces high frequency gain when the TG2 switch
is OFF. The Peak frequency of the tracking phase compensation is at about 1.2KHz when the resistor
connected to PFSET (Pin7) is 510KΩ. It is inversely proportional to the resistor connected to the Pin 7.
The tracking error signal is switched into low pass filter route formed by connecting a capacitor between
the built-in resistor at DFCT (470KΩ) and TDFCT (Pin54) as for tracking error signal.
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