Kenwood DP-3010 Service Manual page 15

DP-3010
26
CIRCUIT DESCRIPTION
Diagram 5-7 shows the timing of each part.
"H™ Level
eo HiZ Crossover Point
#500ms = #9500ms |
t
FCS! — aa mr Hiz
(f = 1 Hz Operation) | I
|
( |
|
Vosc | |
|
if |
i
FE! a |" J
| Focus Search |. Play
4 Focus Servo ON
l. Focus Search Processing Start
SW1|SW2| System Mode
H Vrer ON | Socus Search
HiZ | FEI! OFF | Normal Play
FEI 'OFF i Search
About +0.2 V
(0.4Vp~p) Diagram 5-2 Switch Position
About t0.4V
(0.8Vp-p)
Diagram 5-7 Each Timing of the Focus Servo Signals
A simple explaination of each part is as follows.
1) Triangle Wave Emitting Circuit
The Triangle Wave is emitted in the Oscillator Circuit
(Cosc) into charge and discharge which is then adjusted in
RSI. : .
From this the reference is set by Cosc and Rcsi during
Focus Search.
Rosc is to keep the reference point stable during Focus
Search Start where it is the discharge resistor for Cosc.
Each current Vosc can be calculated as follows:
Vcc 1
losc = +ICSi,
ICS'= Rest Ox 108" q
Rosc
Vosc = lcsc-
1+jwCOsc -ROSC
Furthermore, dur:ng Focus Search, the Vosc Focus Lense
should be set at a level where there is ample space to
move vertically
FCs!
Oscillator
Circuit
2) FSO AMP
Set the Focus Actuator Gain Characteristics, the Gain
together with the Phase Characteristics and the Gain Com-
pensation Reference.
3) Control Circuit
This circuit switches the input to the Focus Error Output
AMP between Focus Servo and Focus Search signals. The
Switch Position is set as in Diagram 5-2.
The Switch Position is set with SEL and can correspond to
three system modes.
The Focus Search Processing Mode is done after Focus
Gain Adjustment as shown in Diagram 5-1 (Page 18). FKIC
signal is used during Focus Gain Adjustmeent and FCSI
and FBRK signals are used during Focus Search.
Normally, FKIC, FCSI and FBRK signals are HiZ.
+21V
Cosc
Diagram 5-8 TriangleWave Producing Circuit
DP-3010
CIRCUIT DESCRIPTION
@ Tracking Error Output AMP
By inputing the Tracking Error Signal just explained, the
Tracking Servo Signal is emitted in reference with Veer. it
is designed so that the gain upto the TSO including the TE
AMP will have any insertion joss of 540 kO (Feedback
Resistance: RNF3 = RQ = R10 + VR3 = 270k. RNF4 =
R20 + R21 = 20 Kohm). (Note: RNF4 does not included
R22 and R23)
The level of the TSO amount is set by using the analog
switches TEL? and TEL2 of TC9201BF to do Tracking Gain
Adjustment. The TSO output voltage is about 8 Vp-p at
this time.
TESH TEOF
VREF
Sample Hold Circuit a
Futhermore, the Pick-up Tracking Actuator Gain Charac-
teristics and the Phase Characteristics are to be used
together for each reference of the Phase Compensation
Circuit.
For detailed information of the operation of TESH, TEOF,
TGUL. TGUH and DFCT pins, refer to the TC9201 BF techni-
cal information.
The insertion loss from TS1 or TS2 to TSO can be calculat-
ed as follows:
RNF3 X RNFS
RT (TS) = 10x 108
| DFCT
Tracking Coil Driver
Phase Compensation Circuit
T : TGUL
Vv
Diagram 5-9 Tracking Error Output AMP Construction
27