Kenwood DP 2000 Service Manual

Page 2

DISASSEMBLY FOR REPAIR . . . . . . ........... 4
BLOCK DIAGRAM ....................... . 6
CIRCUIT DESCRIPTION

1. Description of components . . . . . . ..... . . . . . 7
1-1. CONTROL (X29-1632071) ............ 7
1-2. PROCESSOR (X32-1040~00) ........ . . 7
2. Circuit operation description ............. . 9
2-1. EFM Signal inputs inhibiting circuit ...... 9

2-2. Remote control/Key data
switching circuit ...... . ...... . . . . . 9
2-3. Dropout control circuit ............. 10

2-4. Digital filter

(Doubled oversampling digital filter) . . . . 10
2-5. Invert switch ............ . ....... 11
Principle and operation of 3-beam laser pickup . . 12
3-1. Method for focus error detection

(astigmastism method) .............. 12
3-2. Tracking error detect circuit
(3-beam method) ................. 13
Key operations and displays .............. 14
4-1. Front panel component names
(DP-2000/1000) .................. 14
4-2. Displays ....................... 14
0 Display panel .................. 14
O Displayed data . . . . . ............ 15
0 Displays in DP-2000/1000 states . . . . . 15
4-3. Keys and their functions ............ 18
0 Normal mode .................. 18
o Testmode ............... 20
0 Key effective in test mode and their
functions .................... 21
0 Control flow from power on TOC read . 21
0 Control flow since power on until 01 is
displayed below the TRACK No. indicator
in test mode ........ . ......... 22
0 Control flow after the PLAY key is pushed
in STOP state .................. 22
Main microprocessor (uPD7516HCW-230) ..... 23
5-1. Connection diagram ............... 23
5-2. Block diagram ................... 23

5-3. Terminals and their functions . . . . . . . . . 24

5-4. DP-ZOOO microprocessor peripheral circuit
block diagram ................... 26

5-5. DP-1000 microprocessor peripheral circuit
block diagram ................... 26

CONTENS

6. RF Amplifier IC1 (CXZO109) ............. 27
6-1. Terminal connection diagram ......... 27
6-2. Block diagram ................... 27
6-3. Explanation of functions of components . . 28
6-4. Explanation of operation . . ....... . . . 29

IRFamplifier............. ..... 29
0 Focus error amplifier ............. 29
0 Tracking error amplifier ........... 29
0 Focus OK circuit ............... 29
0 Mirror circuit .................. 30
o EFM comparator . . . . . .......... 30

7. Servo signal processor (CX20108) .......... 31
7-1. Terminal connection diagram . . . . ..... 31
7-2. Block diagram ............. . ..... 31
7-3. Explanation of terminals . . . . . . . . . . . . 32
7-4. Systemcontrol ....... 33
7-5. Serial data truth value table .......... 34
7-6. Explanation of functions ............ 35

o Sox ( ® SENSE is FZC) ....... 35
1) F81, F82 and focus search ....... 35
2) Explanation of F84 ............ 36
3) Focusing procedure ............ 36
4) SENSE ® terminal ........... 37
o $1X(®8ENSEis"A8") 38
1) T61. T62 .................. 38
2) Brake circuit . ............... 39
0 sex ( (5) SENSE is "sz ....... 4o
1) DIRC ® terminal and signal
track jump ................. 40
2) 100 track jump .............. 41
3) 10 track jump ............... 41
4) Access by making joint use of 100, 10
and 1 track jumps ............. 42
o How to use high speed access and
Count Out @ . ................ 42

8. DP-ZOOO Dropout control (I013) ........... 43
8-1. Function ....................... 43
8-2. System control flow ............... 43

8-3. Dropout control microprocessor
(HD447008A39) and peripheral circuits . . 43

8-4. HD447008A39 Signals ............. 44

8-5. HD447008A39 Signal timing ......... 44

Page 36

36

CIRCUIT DESCRIPTION

2) Explanation of F84

This switch is a voltage follower (but the gain is 1.2
times) at the time of 1 and the output is open at the time
of 0, like F82 described earlier. This switCh bears focus
servo ON/OF F as located between focus error input 20
and input of 0P1 described earlier.

$00 $08
Focus OFF +- Focus ON

->

3) Focusing procedure
The polarity is specified as follows for explanation.
0The lens searches in the direction of far -> near to the
disc.
OOutput voltage ® changes as negative -) positive at
this time.
OFurther, the S curve of focus changes as shown in

Fig. 7-6.

Fig. 7-6 8 curve

(29m?) (200ms)

($02)

($00) I
l

, $03
.1

I

|

Drive voltage

Focus error

SENSE

Focus servo is applied with point ® shown in Fig. 7-6
as the actuation point. In general, the time when focus
search is made and the focus servo switch is ON during
passage through point ® . Furthermore, ANDing is made
with focus OK signal (FOK) in order to prevent malopera-
tion.

This IC is of such a design that what is obtained by
comparing the focus error with 0V is output out of SENSE
® terminal as the signal passing through point ® and is
named as FZC (Focus Zero Cross).

Focus OK means a signal that indicates that focus is
applied (may be applied, in this case), and it is output
out of ® terminal of head amplifier ic1 (cx20109) in
X29-1632~71 .

When the above description is summarized, focus is
applied in accordance with a timing chart is as shown in
Fig. 7-7.

*Broken lines in the figure are of
the occasion where focus is not
applied is assumed.

terminal (FZC) l

I Moment when

focus is applied.

l
|
Focus OK '-

(CX20109)

Fig. 7-7 Timing chart of focus OK