JBL SG-2020 Service manual

Soundgear Series

SG2020 SG3030

3 CD Changer Hi-Fi System

PRELIMINARY

SERVICE MANUAL

JBL Incorporated, Inc.

250 Crossways Park Dr.

Woodbury, New York 11797

CONTENTS

SERVICING PRECAUTIONS . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . .3

ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . .

SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . .

ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . .

TROUBLESHOOTING GUIDE. . . . . . . . . . . . . . . . .

WAVEFORMS OF MAJOR CHECK POINTS . . . . . .

WIRING DIAGRAM (SG2020). . . . . . . . . . . . . . . . . . . .

WIRING DIAGRAM (SG3030). . . . . . . . . . . . . . . . . . . . .

BLOCK DIAGRAM (SG2020) . . . . . . . . . . . . . . . . . . . . . . .

BLOCK DIAGRAM (SG3030). . . . . . . . . . . . . . . . . . . . . . .

SCHEMATIC DIAGRAMS (SG2020/3030). . . . . . . . . . . . . .

PCB BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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PACKAGE PARTS LIST (SG2020). . . . . . . . . . . . . . . . . . . . . . . . . .40

MECHANICAL PARTS LIST (SG2020). . . . . . . . . . . . . . . . . . . . . . .40

ELECTRICAL PARTS LIST (SG2020). . . . . . . . . . . . . . . . . . . . . . . .43

PACKAGE PARTS LIST (SG3030). . . . . . . . . . . . . . . . . . . . . . . . . .54

MECHANICAL PARTS LIST (SG3030). . . . . . . . . . . . . . . . . . . . . . .54

ELECTRICAL PARTS LIST (SG3030). . . . . . . . . . . . . . . . . . . . . . . .57

-3-

SERVICING PRECAUTIONS

NOTES REGARDING HANDLING OF THE PICK-UP

1. Notes for transport and storage

1) The pick-up should always be left in its conductive bag until immediately prior to use.

2) The pick-up should never be subjected to external pressure or impact.

2. Repair notes

1) The pick-up incorporates a strong magnet, and so should never be brought close to magnetic materials.

2) The pick-up should always be handled correctly and carefully, taking care to avoid external pressure and
impact. If it is subjected to strong pressure or impact, the result may be an operational malfunction
and/or damage to the printed-circuit board.

3) Each and every pick-up is already individually adjusted to a high degree of precision, and for that reason
the adjustment point and installation
screws should absolutely never be touched.

4) Laser beams may damage the eyes!
Absolutely never permit laser beams to enter the eyes!
Also NEVER switch ON the power to the laser output part (lens, etc.) of the pick-up if it is damaged.

5) Cleaning the lens surface
If there is dust on the lens surface, the dust should be cleaned away by using an air bush (such as used
for camera lens). The lens is held by a delicate spring. When cleaning the lens surface, therefore, a cot­ton swab should be used, taking care not to distort this.

6) Never attempt to disassemble the pick-up.
Spring by excess pressure. If the lens is extremely dirty, apply isopropyl alcohol to the cotton swab. (Do
not use any other liquid cleaners, because they will damage the lens.) Take care not to use too much of
this alcohol on the swab, and do not allow the alcohol to get inside the pick-up.

Storage in conductive bag

NEVER look directly at the laser beam, and don’t let contact
fingers or other exposed skin.

Magnet

How to hold the pick-up

Conductive Sheet

Cotton swab

Pressure

Pressure

Drop impact

-4-

NOTES REGARDING COMPACT DISC PLAYER REPAIRS

1. Preparations

1) Compact disc players incorporate a great many ICs as well as the pick-up (laser diode). These compo­nents are sensitive to, and easily affected by, static electricity. If such static electricity is high voltage,
components can be damaged, and for that reason components should be handled with care.

2) The pick-up is composed of many optical components and other high-precision components. Care must
be taken, therefore, to avoid repair or storage where the temperature of humidity is high, where strong

magnetism is present, or where there is excessive dust.

2. Notes for repair

1) Before replacing a component part, first disconnect the power supply lead wire from the unit

2) All equipment, measuring instruments and tools must be grounded.

3) The workbench should be covered with a conductive sheet and grounded.
When removing the laser pick-up from its conductive bag, do not place the pick-up on the bag. (This is
because there is the possibility of damage by static electricity.)

4) To prevent AC leakage, the metal part of the soldering iron should be grounded.

5) Workers should be grounded by an armband (1MΩ)

6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent
static electricity changes in the clothing to escape from the armband.

7) The laser beam from the pick-up should NEVER be directly facing the eyes or bare skin.

CLEARING MALFUNCTION

You can reset your unit to initial status if malfunction occur(button malfunction, display, etc.).
Using a pointed good conductor(such as driver), simply short the RESET jump wire on the inside of the
volume knob for more than 3 seconds.
If you reset your unit, you must reenter all its settings(stations, clock, timer)

NOTE: 1. To operate the RESET jump wire, pull the volume rotary knob and release it.

2. If you wish to operate the RESET jump wire, it is necessary to unplug the power cord.

Resistor
(1 Mohm)

VOLUME

UP

DOWN

VOLUME KNOB

RESET jump wire

Conductive
Sheet

Resistor
(1 Mohm)

Armband

-5-

ESD PRECAUTIONS

Electrostatically Sensitive Devices (ESD)

Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components com­monly are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated cir­cuits and some field-effect transistors and semiconductor chip components. The following techniques should
be used to help reduce the incidence of component damage caused by static electricity.

1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off
any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a
commercially available discharging wrist strap device, which should be removed for potential shock reasons
prior to applying power to the unit under test.

2. After removing an electrical assembly equipped with ESD devices, place the assembly on a conductive sur­face such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.

3. Use only a grounded-tip soldering iron to solder or unsolder ESD devices.

4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static"
can generate electrical charges sufficient to damage ESD devices.

5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ESD
devices.

6. Do not remove a replacement ESD device from its protective package until immediately before you are
ready to install it. (Most replacement ESD devices are packaged with leads electrically shorted together by
conductive foam, aluminum foil or comparable conductive materials).

7. Immediately before removing the protective material from the leads of a replacement ESD device, touch the
protective material to the chassis or circuit assembly into which the device will by installed.

CAUTION : BE SURE NO POWER IS APPLIED TO THE CHASSIS OR CIRCUIT, AND OBSERVE ALL

OTHER SAFETY PRECAUTIONS.

8. Minimize bodily motions when handing unpackaged replacement ESD devices. (Otherwise harmless motion
such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can gen­erate static electricity sufficient to damage an ESD device).

-6-

SPECIFICATIONS

SECTION SG2020 SG3030

AMP

Output Power 65W+65W (6Ω, 2ch, T.H.D 10%) 30W+30W (6Ω, 2ch, T.H.D 10%)
Woofer 60W+60W (6Ω, 2ch, T.H.D 10%)
Frequency Response(MAIN) 40~25,000 Hz 200~25,000 Hz
Frequency Response(Woofer) 45~120 Hz
Signal-to-Noise Ratio 83dB 83dB

Tuner

FM

Tuning Range(OPTICAL) 87.5 ~ 108 MHz 87.5 ~ 108 MHz
Intermediate Frequency 10.7 MHz 10.7 MHz
Signal-to-Noise Ratio 61/58 dBA 61/58 dBA
(Mono/Stereo, 98MHz)
Frequency Response 60~10,000 Hz 200~10,000 Hz

AM(MW)

Range(OPTICAL) 522~1,611 kHz or 530~1,720 kHz 522~1,611 kHz or 530~1,720 kHz
Intermediate Frequency 450 kHz 450 kHz
Frequency Response 100~2,000 Hz 200~2,000 Hz

SW(OPTICAL)

Tuning Range 5.8~18.0 MHz 5.8~18.0 MHz
Intermediate Frequency 450 kHz 450 kHz
Signal-to-Noise Ratio(11MHz) 35 dB 35 dB 3

LW(OPTICAL)

Tuning Range 153~281 kHz 153~281 kHz
Intermediate Frequency 450 kHz 450 kHz
Signal-to-Noise Ratio(11MHz) 28 dB 28 dB

CASSETTE DECK

FF, REW Time (C-60) 120 sec. 120 sec.
Frequency Response 125~8,000 Hz 250~18,000 Hz
Signal-to-Noise Ratio 43dB(P/B), 43dB(R/P) 43dB(P/B), 43dB(R/P)
Channel Separation 50dB(P/B), 45dB(R/P) 50dB(P/B), 45dB(R/P)

CD

Frequency Response 40~18,000 Hz 200~8,000 Hz
Signal-to-Noise Ratio 70 dB 70 dB

GENERAL

Power Requirements Refer to the back panel of the unit. Refer to the back panel of the unit.
Net Dimensions(WxHxD) 273 x 326 x 344 mm 273 x 326 x 344 mm
Net Weight ? kg ? kg

Speaker System

Type Bass Reflex 2 Way Bi AMP

3 Speaker System (Main Speaker, Super Woofer)

3 Speaker System
Impendance 6Ω 6Ω
Frequency Response(MAIN) 60~20,000 Hz 140~20,000 Hz
Sound Pressure Level(MAIN) 85 dB/W(1m) 90 dB/W(1m)
Rated Input Power(MAIN) 65 W 30 W
Rated Input Power(SUPER WOOFER) 60 W
Max. Input Power(MAIN) 130W 60 W
Max. Input Power(SUPER WOOFER) 120 W
Net Dimensions(WxHxD) 220 x 326 x 252 mm 220 x 372 x 252 mm
Net Weight ? kg ? kg

: EUROPE : UL

NOTE: Designs and specification are subject to change without notice for improvement.

-7-

ADJUSTMENTS

This set has been aligned at the factory and normally will not require further adjustment. As a result, it is not
recommended that any attempt is made to modificate any circuit. If any parts are replaced or if anyone tam­pers with the adjustment, realignment may be necessary.

IMPORTANT

1. Check Power-source voltage.

2. Set the function switch to band being aligned.

3. Turn volume control to minimum unless otherwise noted.

4. Connect low side of signal source and output indicator to chassis ground unless otherwise specified.

5. Keep the signal input as low as possible to avoid AGC and AC action.

TAPE DECK ADJUSTMENT

1. AZIMUTH ADJUSTMENT

2. NORMAL SPEED ADJUSTMENT

Deck Mode

A Deck Playback MTT-114 Speaker Out

DECK Screw

Azimuth Screw

Maximum

B Deck Playback MTT-114 Speaker Out Azimuth Screw Maximum

Test Tape Test Point Adjustment Adjust for

Deck Mode

Normal Speed MTT-111 Speaker Out VR201 3kHz ± 1%

Hi-Speed MTT-111 Speaker Out more than 5.4kHz

A Deck

Hi-Speed

Dubbing Mode

Test Tape Test Point Adjustment Adjust for Remark

CH1 CH2

Speaker Out

Playback Mode

Head

Test Tape
MTT-114

L ch

R ch

GND

Dual-trace
synchroscope

Electronic
Voltmeter

L out

R out

Unit

Figure 1. Azimuth Adjustment Connection Diagram

Head

Playback Mode

Unit

Speaker Out

GND

L out

R out

Record/Playback
head

Test Tape
MTT-111

Frequency Counter

Figure 2. Normal Speed Adjustment Connection Diagram

3. RECORD BIAS ADJUSTMENT

4. TUNER ADJUSTMENT

-8-

Deck Mode

Rec/Pause MTT-5511

ERASE HEAD

WIRE(PN402)

L201

60kHz±5kHz (Auto-stop)

85kHz±5kHz (Auto-Reverse)

Test Tape Test Point Adjustment Adjust for

Item

DC Voltage Checker Pin TP101, 102 0V±50mV

Test Point Adjustment Adjust for

Head

Unit

PN402

GND

Record/Playback
head

Test Tape
MTT-5511

Record/Playback
and Pause Mode

Frequency Counter

Figure 3. Record Bias Adjustment Connection Diagram

Unit

Signal Generator

GND

Electronic
OSCILLOSCOPE

FM Antenna
Terminal

Speake

Figure 4. Tuner(S curve) Adjustment Connection Diagram

-9-

TROUBLESHOOTING GUIDE

Turn power on.

Is power on?

Does initial read work?

Does it play?

Does it output audio?

Check power supply circuit.

(Check PN 807)

Check laser circuit.

Check focus circuit.

Check disc.

Check tracking servo circuit.

Check audio circuit.

OK

YES

YES

YES

YES

NO

NO

NO

NO

Fails to initial read

-10-

1.3V

A
B

YES

YES

YES

YES

YES

YES

YES

YES

NO

NO

NO NO NONO

NO

NO

NO

NO

Does laser light?

Disc motor turns.

Does RF
waveform
appear?

TP 801(RF)

Does tracking
servo work?
Lower envelope
of TP801(RF)
waveform is flat.

Does signal
appear at
TP801(TEO)?

Does signal appear at IC 803
Pin and Pin ?

Does GFS (IC802 pin )
show as below?

Is rotation normal?

Is there no dropout of RF
signal?

Does TE2 signal
appear at pin

53

of IC801?

Defective IC
801, pick up
and/or open
wire.

Detective pattern.

Defective IC 801
and/or IC 803

Defective pick-up
and/or connector.

Defective IC 801.

Scratch in disc
initial read area.

Defective pick-up

adjustment focus offset.

26 27

25

-11-

A

NO

NO

NO

NO

NO

NO

Laser does not light.

Is “3.5V” applied to pin of IC 801?

Is power supplied to laser Q801?

(Q 801 collector: about 1.8V)

Does laser current flow?

1.0V across R801

Is data transferred from
MICOM IC ?

Does voltage appear at IC
803 pin , ?

Defective MICOM.

Defective MICOM.

Defective connector.

Defective IC 801, 803

Defective slide motor and/or
connector.

Defective LMT SW and/or
connector.

Defective Q 801 and/or laser.

Defective laser and/or
connector.

Did pickup return to

innermost circular?

Does it stop at inner pick
circular after shift?

Is defect output from LM
SW applied to pin of

PN803?

R801 1.0V

R801 1.0V

YES

YES

YES

YES

OPEN

CLOSE

YES

YES

YES

YES

YES

YES

70

11 12

2

-12-

B

C

Does lens move up/down?

Does IC 801 out focus
search signal?

IC 801 pin (FEO)

Is focus search signal
applied to pin , of
CN801?

Laser lights.

Confirm

initial

read with

disc

Defective IC801

Defective IC803

Defective IC 801.

Open activator and/or
connector.

Open connector and/or
defective IC 801.

Incorrect turntable height.
Degraded laser diode.

Does TP 801 RF signal appear even in
low level?

Is laser output adjustment correct?

Does FOK(focus ok) signal appear?

YES

YES

YES

YES

YES

YES

TP801
(RF)

IC801 pin
(FOK)

NO NO

NO

NO

NO

NO

48

13 16

40

-13-

FER

ISTAT(SENSE)

C

Start mode

Does FE1 signal appear? IC 801 pin

Does FZC signal (focus zero cross signal)
appear at pin of IC 801, ISTAT (SENSE)
terminal?

Does SMON signal appear
at pin of IC 802?

Does SMPO signal appear
at pin of IC 802?

Is drive voltage applied to disk motor?

Defective IC 801.

Open pick diode

Defective IC 801.

Defective Pattern between IC 801 and
IC 802.

Defective IC 801, 803 and/or
peripheral circuit.

Defective disk motor and/or insulation.

(Focus servo turns
ON by FZC signal
of FOK mod.)

NO

NO

NO

NO

YES

YES

YES

YES

YES

59

31

73

75

-14-

WAVEFORMS OF MAJOR CHECK POINT

1. HF signal (RF signal ) waveform
(Test Point TP801) during normal play

2. EFM signal (pin IC 801)waveform
during Normal Play

0V

0V

3. Focus coil drive waveform(Pin NO 1, 2 of IC 803)

• When focus search failed or there is no disc on
the tray

3. Focus coil drive waveform(Pin NO , of IC 803)

• Focus coil drive waveform(pin NO 1, 2 of
IC803) and FOK (pin NO 40 of IC 801) when
focus search is accomplished

0V

CH1 : FOCUS COIL DRIVE

SIGNAL 2V/Div.

CH2 : FOAK

(

CH1 : TEO(TP801) 1V/Div.
CH2 : TRACKING COIL DRIVE

SIGNAL 2V/Div.

(

CH1 : TEO(TP801) 1V/Div.
CH2 : TRACK COIL DRIVE

SIGNAL 2V/Div.

(

CH1 : TEO(TP801) 1V/Div.
CH2 : TRACK COIL DRIVE

SIGNAL 2V/Div.

(

0V
(CH1)

0V
(CH2)

4. Tracking coil drive waveform (pin NO 26, 27
of IC 803) and TEO during track traverse
(1) When time division is 20nS/div

4. Tracking coil drive waveform (pin NO 26, 27 of IC

803) and TEO during track traverse

(2) When time division 0.5nS/div.

(During forward track traverse)

0V
(CH1)

0V
(CH2)

0V
(CH1)

0V
(CH2)

(3) When time division is 0.5nS/div.

(During backward Track Traverse)

5. Feed motor drive waveform(pin NO 11, 12
of IC 803) During normal play

0V

0V
(CH2)

0.5V/Div.
500nS/Div.

(

2V/Div.
500nS/Div.

(

0.5V/Div.
500nS/Div.

(

0V

WIRING DIAGRAM

(MODEL : SG2020)

-15-

-16-

WIRING DIAGRAM

(MODEL : SG3030)

BLOCK DIAGRAM

(MODEL : SG2020)

-17-

BLOCK DIAGRAM

(MODEL : SG3030)

-18-

22