Harman Kardon FL8385 Service Manual page 17

FL8385
Focus System
E
A B
C D
F
PDIC
The focus error output of A, B, C and D are given to Pin 27. C4 is required for oscillation-
proof. R7 is set such that FEOUT of Pin 27 becomes 1.46 Vp-p.
During alignment procedure, the DSP IC (MN662790) will adjust the focus balance voltage
V from Pin 30. V
FBAL
±0.5 V.
The focus gain will change according to the type of disc. For normal disc or CDR disc,
V is set to V
GCTRL REF2
tracking gain is changed too.
36
35
34
33
varies with reference to the center voltage V
FBAL
; for CDRW disc V
GCTRL
C47 R27
R21
R20
C35
3 5
GCTRL
28
V
GCTRL
C2
is set to V - 0.75 V. At the same time, the
REF2
17
harman/kardon
FL8380
Subtraction
FBAL
FEN
29 27 26
R7
C3
R6
C4
V
FEOUT
FBAL
(=1.65 V) within
REF2