Sony Model CDX-L280 User manual

1
Model Name Using Similar Mechanism NEW
CD Drive Mechanism Type MG-393XC-121//K
Optical Pick-up Name KSS-721A
SERVICE MANUAL
AEP Model
UK Model
CDX-L280
FM/AM COMPACT DISC PLAYER
CD player section
Signal-to-noise ratio 90 dB
Frequency response 10 – 20,000 Hz
Wow and flutter Below measurable limit
Tuner section
FM
Tuning range 87.5 – 108 MHz
Aerial terminal External aerial connector
Intermediate frequency 10.7 MHz
Usable sensitivity 11 dBf
Selectivity 75 dB at 400 kHz
Signal-to-noise ratio 65 dB (stereo),
68 dB (mono)
Harmonic distortion at 1 kHz
0.7% (stereo),
0.5% (mono)
Separation 33 dB at 1 kHz
Frequency response 30 – 15,000 Hz
AM
Tuning range 531 – 1,602 kHz
Aerial terminal External aerial connector
Intermediate frequency 10.7 MHz/450 kHz
Sensitivity 30 µV
Power amplifier section
Outputs Speaker outputs
(sure seal connectors)
Speaker impedance 4 – 8 ohms
Maximum power output 45 W ×4 (at 4 ohms)
SPECIFICATIONS
General
Outputs Audio outputs (rear)
Power amplifier control terminal
Power aerial relay control terminal
Tone controls Bass ±9 dB at 100 Hz
Treble ±9 dB at 10 kHz
Power requirements 12 V DC car battery
(negative ground)
Dimensions Approx. 178 ×50 ×176 mm
(w/h/d)
Mounting dimensions Approx. 182 ×53 ×161 mm
(w/h/d)
Mass Approx. 1.2 kg
Supplied accessories Parts for installation and
connections (1 set)
Front panel case (1)
Note
This unit cannot be connected to a digital
preamplifier or an equalizer.
Design and specifications are subject to change without
notice.
Ver 1.0 2002. 11
9-874-228-01
2002K0400-1
© 2002. 11
Sony Corporation
e Vehicle Company
Published by Sony Engineering Corporation

2
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK 0OR DOTTED LINE
WITH MARK 0ON THE SCHEMATIC DIAGRAMS AND IN
THE PARTS LIST ARE CRITICAL TO SAFE OPERATION.
REPLACE THESE COMPONENTS WITH SONY PARTS WHOSE
PART NUMBERS APPEAR AS SHOWN IN THIS MANUAL OR
IN SUPPLEMENTS PUBLISHED BY SONY.
SERVICE NOTES
NOTES ON HANDLING THE OPTICAL PICK-UP BLOCK
OR BASE UNIT
The laser diode in the optical pick-up block may suffer electrostatic
breakdown because of the potential difference generated by the
charged electrostatic load, etc. on clothing and the human body.
During repair, pay attention to electrostatic breakdown and also use
the procedure in the printed matter which is included in the repair
parts.
The flexible board is easily damaged and should be handled with
care.
NOTES ON LASER DIODE EMISSION CHECK
The laser beam on this model is concentrated so as to be focused on
the disc reflective surface by the objective lens in the optical pick-
up block. Therefore, when checking the laser diode emission, ob-
serve from more than 30 cm away from the objective lens.
Notes on Chip Component Replacement
•Never reuse a disconnected chip component.
•Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
CDX-L280
This label is located on the bottom of the
chassis.
This label is located on the drive unit's internal
chassis.
When replacing the chassis (T) of mechanism deck which have
the “CAUTION LABEL” attached, please be sure to put a new
CAUTION LABEL (3-223-913-11) to the chassis (T).
CAUTION–INVISIBLE LASER RADIATION WHEN OPEN
DO NOT STARE INTO BEAM OR
VIEW DIRECTLY WITH OPTICAL INSTRUMENTS

3
CDX-L280
MAIN BOARD CNP701
SERVO BOARD CN1
TEST DISCS
This set can playback CD-R and CD-ROM discs. The following
test discs should be used to check the capability:
CD-R test disc TCD-R082LMT (Part No. J-2502-063-1)
CD-RW test disc TCD-W082L (Part No. J-2502-063-2)
Notes on CD-R/CD-RW discs
•You can play CD-Rs (recordable CDs)/CD-RWs (rewritable CDs)
designed for audio use on this unit.
Look for these marks to distinguish CD-Rs/CD-RWs for audio
use.
These marks denote that a disc is not for audio use.
•Some CD-Rs/CD-RWs (depending on the equipment used for
its recording or the condition of the disc) may not play on this
unit.
•You cannot play a CD-R/CD-RW that is not finalized*.
*Aprocess necessary for a recorded CD-R/CD-RW disc to be
played on the audio CD player.
EXTENSION CABLE AND SERVICE POSITION
Whenrepairingorservicingthisset,connectthejig(extensioncable)
as shown below.
•Connect the MAIN board (CNP701) and the SERVO board
(CN1) with the extension cable (Part No. J-2502-062-1).

4
TABLE OF CONTENTS
1. GENERAL
Location of controls................................................................. 5
Connections ............................................................................. 6
2. DISASSEMBLY
2-1. Sub Panel Assy .................................................................... 7
2-2. CD Mechanism Block ......................................................... 8
2-3. Main Board ......................................................................... 8
2-4. Heat Sink ............................................................................. 9
2-5. Chassis (T) Sub Assy .......................................................... 9
2-6. Lever Section..................................................................... 10
2-7. Servo Board....................................................................... 10
2-8. Shaft Roller Assy .............................................................. 11
2-9. Floating Block Assy .......................................................... 11
2-10. Optical Pick-up Block ....................................................... 12
3. DIAGRAMS
3-1. IC Pin Description............................................................. 13
3-2. Block Diagram –CD Section–........................................... 15
3-3. Block Diagram –Tuner Section– ....................................... 16
3-4. Block Diagram –Display Section–.................................... 17
3-5. Circuit Boards Location .................................................... 17
3-6. Printed Wiring Boards –CD Mechanism Section–............ 18
3-7. Schematic Diagram –CD Mechanism Section– ................ 20
3-8. Printed Wiring Board –Main Section– .............................. 21
3-9. Schematic Diagram –Main Section (1/2)– ........................ 22
3-10. Schematic Diagram –Main Section (2/2)– ........................ 23
3-11. Printed Wiring Board –Display Section– .......................... 24
3-12. Schematic Diagram –Display Section–............................. 25
4. EXPLODED VIEWS
4-1. Chassis Section ................................................................. 28
4-2. Front Panel Section ........................................................... 29
4-3. CD Mechanism Section (1) ............................................... 30
4-4. CD Mechanism Section (2) ............................................... 31
4-5. CD Mechanism Section (3) ............................................... 32
5. ELECTRICAL PARTS LIST ........................................ 33
CDX-L280

55
CDX-L280
SECTION 1
GENERAL This section is extracted
from instruction manual.

66
CDX-L280

7
CDX-L280
SECTION 2
DISASSEMBLY
Note : This set can be disassemble according to the following sequence.
Note : Follow the disassembly procedure in the numerical order given.
2-1. SUB PANEL ASSY
2-1. SUB PANEL ASSY
(Page 7)
2-5. CHASSIS (T) SUB ASSY
(Page 9)
2-6. LEVER SECTION
(Page 10)
SET
2-7. SERVO BOARD
(Page 10)
2-2. CD MECHANISM BLOCK
(Page 8)
2-3. MAIN BOARD
(Page 8)
2-4. HEAT SINK
(Page 9)
2-8. SHAFT ROLLER ASSY
(Page 11)
2-9. FLOATING BLOCK ASSY
(Page 11)
2-10. OPTICAL PICK-UP BLOCK
(Page 12)
1 PTT 2.6x6
2 PTT 2.6x6
3 claw
5 sub panel assy
4 claws
three claws

8
CDX-L280
3 screw (+BTT)
4 screws (+BTT)
1 PTT 2.6x8
5 MAIN board
2 PTT 2.6x
8
1 PTT 2.6x6
6 PTT 2.6x
6
7 bracket (CD)
2 PTT 2.6x6
5 CD mechanism block
4 CNP701
3
2-3. MAIN BOARD
2-2. CD MECHANISM BLOCK

9
CDX-L280
4 chassis (T) sub assy
3 P 2x3
2 P 2x3
1 Unsolder the
lead wires.
black
red
white
6 heat sink
1 PTT 2.6x8
2 PTT 2.6x8
4 PTT 2.6x8
3 PTT 2.6x12
5 PTT 2.6x8
2-5. CHASSIS (T) SUB ASSY
2-4. HEAT SINK

10
CDX-L280
4 claws
2 IN SELF SW board
7 lever (L)
3 tension spring (LR)
6 lever (R)
5 guide (disc)
1 special screw
2-6. LEVER SECTION
2-7. SERVO BOARD
6 special screws
1 CN3
2 Removal the solders.
4 P 2x3
5 loading motor assy
8 SERVO board
7 special screw
9 connector
optical pick-up block
3 Unsolder the
lead wires.
black
yellow

11
CDX-L280
1 tension spring (KF1)
7 compression spring (FL)
6 floating block assy
8 compression spring (FL)
4 Fit lever (D) in the
direction of the arrow.
2 damper (T)
3 damper (T)
5 Turn loading ring in the
direction of the arrow.
Fig. 1
1 tension spring (RA)
2 arm (roller)
3 retaing ring (RA)
4 shaft retainer (roller)
5 shaft roller assy
6 special screw
7 LOAD-SW board
retaing ring
(RA) arm arm
washer washer shaft retainer
(roller)
shaft retainer (roller)
2-9. FLOATING BLOCK ASSY
2-8. SHAFT ROLLER ASSY
• When installing, take note of the positions
arm (roller) and washers. (Fig. 1)

12
CDX-L280
2-10. OPTICAL PICK-UP BLOCK
1 P 2x3
4 screw
5 plate spring (feed)
6 shaft (feed) assy
2 sled motor assy
3 optical pick-up block

13
CDX-L280
3-1. IC PIN DESCRIPTION
• IC801 µPD780024AGK-C08-9ET (SYSTEM CONTROLLER)
Pin No. Pin Name I/O Pin Description
1DSW I Down switch detection input
2IN SW I Disc in switch detection input
3PH3 I PH3 detection input (Not used in this set)
4 LM LD O Loading motor drive output (Loading)
5 LM EJ O Loading motor drive output (Eject)
6AATTOPower amplifier mute control output
7ATT O Line out mute control output
8BEEP O BEEP output
9VSSO — Ground
10 VDDO — Power supply pin (+5 V)
11 VOL CLK O Electric volume clock output
12 VOL DO O Electric volume data out output
13 VOL CE O Electric volume chip enable output
14 AM ON O Tuner AM power supply control output
15 FM ON O Tuner FM power supply control output
16 NOSE I Front panel attachment detection input
17 PLL DI I PLL IC data input
18 LCD DO O LCD data output
19 LCD CE O LCD chip enable output
20 LCD CLK O LCD clock output
21 PLL CLK O PLL IC clock output
22 PLL DO O PLL IC data output
23 PLL CE O PLL IC chip enable output
24 VDD1 — Power supply pin (+5 V)
25 AVSS — Ground
26 ST IND I FM STEREO detection input
27 FUN SEL I Function select input
28 S METER I S meter signal input
29, 30 KEY0, 1 I A/D key input 0, 1
31 TEL ATT I Attenuator signal input (Connect to ground in this set)
32 DST SEL I Destination select input (Fixed at “L” in this set)
33 TEST I Force test mode input
34 AVREF — A/D converter power supply pin (+5 V)
35 AVDD — A/D converter power supply pin (+5 V)
36 RESET I Reset input
37 XT2 O Sub clock output (32.768 kHz)
38 XT1 I Sub clock input (32.768 kHz)
39 IC — Connect to Ground in this set.
40 X2 O Master clock output (8.38 MHz)
41 X1 I Master clock input (8.38 MHz)
42 VSS1 — Ground
43 KEY ACK I Key acknowledge detection input
44 SIRCS I SIRCS input
45 SELF SW I Self switch detection input
46 BU IN I Backup power supply detection input
47 AD ON O Key power supply control output
48 ILL ON O Illumination power supply control output
49 AMP ON O Amplifier remote power supply control output
50 CDM ON O CD mechanism deck power supply control output
51 XCD ON O CD DSP IC 16 MHz X’tal ON/OFF control output
52 TU ON O Tuner power supply control output
SECTION 3
DIAGRAMS

14
CDX-L280
Pin No. Pin Name I/O Pin Description
53 P.ON O System power supply control output
54 X SO O CD DSP IC serial data output
55 X SI I CD DSP IC serial data input
56 X SCK O CD DSP IC serial clock output
57 RFOK I CD servo IC RFOK signal input
58 X RST O CD DSP IC reset control output
59 ACC IN I Accessory power supply detection input
60 AO O CD servo IC command/pallameter discrimination signal output
61 STB O CD servo IC data strobe signal output
62 XEN O CD DSP IC X’tal control output
63 L SW I Limit switch detection input
64 PH1 I PH1 detection input (Not used in this set)

15 15
CDX-L280
82
83
84
85
16
12
D/A
CONV
TRACKING
ERROR
FORCUS
ERROR
9
1
OSC
EFM
DEMOD
SERVO
CTL
RF
EQ
52
56
54
55
DSUB CODE
PROCESS
8
7
6
5
4
3
2
62
1
45
2
63
50
51
54
55
56
61
60
58
57
I/F
87
86
97
98
LD
DRIVE
Q1
FOCUS
COIL
DRIVE
TRACKING
COIL
DRIVE
SLED
MOTOR
DRIVE
SPINDLE
MOTOR
DRIVE
LOADING
MOTOR
DRIVE
6
5
23
2
15
16
17
18
13
14
11
12
9
10
26
62 63 64 65
5
4
36
POWER
CONTROL
Q905,906
POWER
CONTROL
Q921
REG
Q907,D908
REG
Q910,D910
M902
(SLED)
M901
(SPINDLE)
M903
(LOADING)
SW3
(DISC IN)
SW2
(SELF)
SW4
(LIMIT)
SW5
(DOWN)
X1
16.9344MHz
OPTICAL PICK-UP
KSS-721A
I-V
CONV.
CDL
STB
A0
X_SO
X_SI
X_SCK
X_RST
RFOK
XEN
D_SW
IN_SW
SELF_SW
L_SW
LM _LO
LM_ EJ
CDM ON
XCD_ON
R-CH
MAIN
SECTION
A
23 24
M
M
M
1RESET
S901
RESET
2
IC902
U_COM+5V
BATT
D909
LOUT
ROUT
PACK
TSTB
TSI
TSCK
SI
RFOK
SO
SCK
STB
AO
XTALEN
RST
RESET
A
C
B
D
E
F
PD
LD
A
C
B
D
E
F
PD
LD
APC
FCS-
FCS+
TRK+
TRK-
SL-
SL+
SP+
SP-
LD-
LD+
FOCUS
COIL
TRACKING
COIL
FD
TD
SD
MD
LOAD
EJECT
SYSTEM CONTROL
IC801(1/3)
RF AMP,DIGITAL SERVO
DIGITAL SIGNAL PROCESSOR
IC1
FOCUS/TRACKING COIL DRIVE
SLED/SPINDLE/LOADING MOTOR DRIVE
IC2
FD TD SD MD
• Signal path
:CD
A_5V
AU_5V
D_5V
DR_6V
3-2. BLOCK DIAGRAM — CD SECTION —
(Page 16)

1616
CDX-L280
CNJ601
(ANTENNA) 2 16
1
FM_ANT L-CH
17
R-CH
CDL
24
DET_OUT
11
FM/AM_OSC
14
AM_VT
6
FM_VT
20
IF_CONT
19
OSC-IN
21
12
9
S_METER
TU+B
22
SD/ST_IND
FM_VCC
AM_VCC
PLL VCC
AM_ANT
TUNER UNIT
TU601
11
12
13
2
1
36
17
21
18
14
5
SYSTEM CONTROL
IC801 (2/3)
PLL
IC601
ELECTRONIC VOLUME
IC401
LF OUT
4
33
34
LR OUT
RF OUT R-CH
RR OUT
8
BEEP
ATT
53
7
P.ON
6
A_ATT
31
TEL ATT
59
ACC IN
L5
L1
L2
R2
CE
DI
CL
VOL_CLK
VOL_DO
VOL_CE
17
22
21
PLL_DI
PLL_DO
PLL_CLK
23 PLL_CE
LCL
DST_SEL
S_METER
FM POWER
CONTROL
Q605,606
SD_IND
AUDIO OUT REAR
CD
SECTION
A
MUTE
CONT
Q401,402
Q102
MUTE
R-CH
DELAY BATT
BATT
Q909
BATT
D402
Q101
MUTE
22 MUTE
4STBY
16 AUX-IN
11
12 5
3
9
7
POWER AMP
IC101
1
9
2
10
CNP501
R-CH
PJ401
FL+
FL-
RL+
RL-
4
12
FR+
FR-
3
11
RR+
RR-
16 +B (BATT)
5AMP REM
6
8
19
ANT REM
GND
R-CH
F901
10A
7ACC
15 TEST
33
TEST
AMP_ON
ACC
CHECK
Q902
32
26
28
17
18
L
R
• Signal path
:FM
:AM
:CD
ANT REMOTE
CONTROL
Q911,917
BACK-UP CHECK
Q903,904,D906,907
TUNER+8V REG
Q912,913,D913
COM+8V REG
Q918,919,929,D923
U_COM+5 V REG
Q920,D930,D999
U_COM+5V
COM+8V
TU+B
R-CH
8
FM_VCO
15
AM_VCO
16
FM_CP
18
VT
19
AM_CP
20
OSC
2
SEEK XO
XI
10
IFC
13
MONO
11 24
1
CE 3
CK 5
D_IN 4
D_OUT 6
X601
10.25MHz
4
3
AM_DX/LCL
FM_DX/LCL
52
TU_ON
46
BU_IN
15
FM_ON
14
AM_ON
49
AM POWER
CONTROL
Q603,604
• R-ch is omitted due to same as L-ch.
3-3. BLOCK DIAGRAM — TUNER SECTION —
(Page 15)

17 17
CDX-L280
3-4. BLOCK DIAGRAM — DISPLAY SECTION — 3-5. CIRCUIT BOARDS LOCATION
KEY MATRIX
S501-511,
S512-521
KEY
ACTIVE
Q916
IR
RECEIVER
IC552
X802
32.768kHz
37
38
40
41
29 18
20
1930
43
47
44
SYSTEM CONTROL
IC801 (3/3)
LCD DRIVE
IC551
KEY 0 DATA
CLK
CE
LCD DO
LCD CLK
LCD CE
ILL POWER
CONTROLLER
Q914
INITIAL
RESET
D552
SWITCH
Q915
ILL + B
KEY 1
KEY 1
KEY 0
KEY ACK
AD ON
SIRCS
XT2
XT1
X2
48
ILL ON
BATT
X1
X801
8.38MHz PL551,552
D561-581
LCD BACK
LIGHT
62
61
60
COM1
COM2
LCD
LCD501
D914
()
KEY
ILLUMINATION
()
64
•
63
1
|
23
•
25
|
53
•
SEG1
SEG52
|
DATA
CLK
CE
ILL+B
57
INH
MAIN board
tuner unit
(TU601)
DISPLAY board
SPEAKER board
IN SELF SW board
SW board
LOAD-SW board
SL SW board
• Waveforms
— Servo Board —
(MODE: CD PLAY)
1
2
3
IC1 ts (PACK)
IC1 uj (RFO)
1.2Vp-p
4
Approx. 1Vp-p
IC1 oa (FEO)
0V
5
Approx. 400mVp-p
IC1 od (TEO)
4.4Vp-p
16.9344MHz
IC1 wd (XTAL)
3Vp-p
0V
22.7µsec
— Main Board —
1
2
32.768kHz
IC801 ej (XT2)
3.8Vp-p
5Vp-p
8.38MHz
IC801 r; (X2)

1818
CDX-L280
3-6. PRINTED WIRING BOARDS — CD MECHANISM SECTION — • Refer to page 17 for Circuit Boards Location.
1
A
B
C
D
E
F
G
H
I
J
234567891011
CN2
THIS NOTE IS COMMON FOR PRINTED WIRING
BOARDS AND SCHEMATIC DIAGRAMS.
(In addition to this, the necessary note is
printed in each block.)
for schematic diagram:
•All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
•All resistors are in Ωand 1/4W or less unless otherwise
specified.
•%: indicates tolerance.
•f: internal component.
•C: panel designation.
•A: B+ Line.
•Powervoltage is dc14.4Vand fedwithregulated dc power
supply from ACC and BATT cords.
•Voltagesare takenwitha VOM(Inputimpedance 10MΩ).
Voltage variations may be noted due to normal produc-
tion tolerances.
•Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal produc-
tion tolerances.
•Circled numbers refer to waveforms.
•Signal path.
F: FM
f: AM
J: CD
for printed wiring boards:
•X: parts extracted from the component side.
•Y: parts extracted from the conductor side.
•x: parts mounted on the conductor side.
•a: Through hole.
•: Pattern from the side which enables seeing.
(The other layer’s patterns are not indicated.)
Caution:
Pattern face side: Parts onthe patternfaceside seenfrom the
(Side B) pattern face are indicated.
Parts face side: Parts on the parts face side seen from the
(Side A) parts face are indicated.
Note: The components identified by mark 0or dotted line
with mark 0are critical for safety.
Replace only with part number specified.

19 19
CDX-L280
1
A
B
C
D
E
F
G
H
I
J
234567891011121314
SW3
SW2
SW4
SW5
TP8
C45
C4
C26
C37
TP6
TP1
TP2
TP4
TP5
TP87
TP86
TP57
TP77
TP11
TP79
TP83
TP70
TP9
TP27
TP12
TP78
TP10
TP81
TP84
TP54
TP25
TP24
TP37
TP39
TP36
TP38
TP40
TP45
TP22
TP88
TP41
TP46
TP21
TP17
TP20
TP42
TP19
TP28
TP90
C41
TP29
C44
TP73 TP32
TP48
TP71
TP51
TP49
TP52
TP55
TP75
TP53
M903
TP56
TP43
TP58
TP61
TP74
TP68
TP80
TP7
TP62
TP91
TP63
C40
TP66
TP64
TP69
TP72
TP50
TP26
TP3
TP59
TP76
TP18
TP89
TP30
R8
R9
R5
R7
R12
R14
R15
R10
R17
R18
R19
R20
R22
FB1
TP92
C3
C5
C6
C8
C9 C10
C11
C13
C14
C16
C18
C19
C24
C25
C29
C34
C36
C38
C35
C21
C22
C30
C23
C1
C27
R21
TP47
C15
C20
TP35
TP23
C17
TP82
TP44
Q1
R26
TP34
R3
TP16
TP85
IC1
IC2
C43
R30
R29
X1
TP60
CN3
CN1
M901
M902
CN13
(Page 21)

2020
CDX-L280
IC B/D
IC B/D
TP77
TP78
R29
R30
C43
TP79
TP80
TP81
TP82
TP83
TP84
CN2
CN3
TP85
M902
M901
SW2 TP4
TP2
TP3
M903
TP87
TP86
TP9 TP8
R3 R26
C4
TP10
C13
R5
C11
C10
C8
TP7
TP92
TP17
TP20
TP16
TP19
TP21
TP18
R7
TP6
C17
FB1
TP11
TP12 C9
C14
TP89
C19
C20 C23
R9
R8
TP22
TP23
TP24
TP25
TP88
C26
TP32
R14
R15
TP30
R12
R10
TP91 C37
TP90
TP29
TP28
TP26
TP27
R21
R22
TP34
TP35
TP36
TP46
TP37
TP38
TP39
TP40
TP41
TP42
TP43
TP44
TP45
CN1
R18
R19
R20
R17
TP66
TP62
TP47
TP63
TP48
TP49
TP64
TP50
TP51
TP52
TP68
TP53
TP69
TP54
TP70
TP55
TP71
TP56
TP72
TP57
TP73
TP58
TP74
TP59
TP75
TP60
TP76
TP61
X1
SW3
SW4
CN13
Q1
C18
IC2
IC1
TP1
TP5
C44
C40
C1 C5 C3 C6
C15
C16
C41
C27
C45
C34
C29
C25
C36
C38
C35
C24
C30
C22
C21
SW5
• Refer to page 17 for Waveforms.
3-7. SCHEMATIC DIAGRAM — CD MECHANISM SECTION — • Refer to page 26 for IC Block Diagrams.
(Page 23)
Note:
•Voltage and waveforms are dc with respect to ground
under no-signal (detuned) conditions.
no mark : CD PLAY