LG CM9540 Schematic

Mini Hi-Fi System

SERVICE MANUAL

MODEL:

CM9540

(CM9540, CMS9540F/W)

CAUTION

BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”

IN THIS MANUAL.

MODEL: CM9540 (CM9540, CMS9540F/W)SERVICE MANUAL

4102 ,MARCH76592129NFA : ON/P

Website http://biz.lgservice.com

Internal Use Only

CONTENTS

SECTION 1 ........ GENERAL

SECTION 2 ........ CABINET & MAIN CHASSIS

SECTION 3 ........ ELECTRICAL

SECTION 4 ........ REPLACEMENT PARTS LIST

1-1

SECTION 1

SUMMARY

CONTENTS

SERVICING PRECAUTIONS ................................................................................................................... 1-3

ESD PRECAUTIONS .................................................................................................................................. 1-5

HIDDEN KEY MODE................................................................................................................................... 1-6

SERVICE INFORMATION FOR EEPROM .......................................................................................... 1-7

PROGRAM DOWNLOAD & UPDATE GUIDE ................................................................................... 1-8

SPECIFICATIONS ..................................................................................................................................... 1-12

1-2

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 lens.

6) Never attempt to disassemble the pick-up.

Spring has 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

Drop impact

NEVER look directly at the laser beam, and don’t allow

contact with fingers or other exposed skin.

Magnet

How to hold the pick-up

Conductive Sheet

Cotton swab

Pressure

1-3

SERVICING PRECAUTIONS

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 or humidity is high, where strong magnet-

ism 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 (1 MΩ)

6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent stat-

ic 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.

Resistor

(1 MΩ)

Conductive

Sheet

Resistor

(1 MΩ)

Armband

1-4

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).

CAUTION. GRAPHIC SYMBOLS

THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS

INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED

“DANGEROUS VOLTAGE” THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF

ELECTRIC SHOCK.

THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE

SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE

LITERATURE.

1-5

ESD PRECAUTIONS

1-6

Push both Front key and RCU key to activate it for 5 seconds.

1. Disc Lock On/Off (CD Function Only Active)

 Front Key : STOP

 RCU Key : STOP

2. Check Version and Option code

 Front Key : STOP

 RCU Key : PLAY/PAUSE

 You can change [Audio MCU Version <-> CD Controller Version <-> EEPROM Option] by SKIP+/-.

3. Clear EEPROM

 Front Key : STOP

 RCU Key : SKIP-

4. Edit EEPROM

 Front Key : STOP

 RCU Key : SKIP+

 You can change the digit of option by SKIP+/-.

 You can edit 0~f by REPEAT or PLAY/PAUSE key.

5. Bluetooth DUT

 Front Key : STOP

 RCU Key : PROGRAM

 Bluetooth model only

6. Power Disc Lock On/Off (CD Function Only Active)

 Front Key : STOP

 RCU Key : EQ

7. Amp Clip On/Off

 Front Key : STOP

 RCU Key : Mute

Amp Clip Mode Change (Amp Clip On --> Amp Clip Off --> Level Down display)

HIDDEN KEY MODE

POWER ON

FLD “NO DISC” status

It is possible at any function.

(ex. It is possible at FLD “NO USB” status, too.)

This is an example.

Remote control ‘ ’ + Front ‘STOP’

push same timing during 5 seconds.

FLD “op0-…..”

Move to appropriate position and

make changes with remote control.

( , , /■ , REPEAT )

Press STOP key

FLD “WRITE OK”

Remote control ‘ ’ +

Front ‘STOP’ push same timing.

FLD “e2p clr”

Completed

NAME

OP0

OP1

OP2

OP3

OP4

OP5

OP6

OP7

OP8

OP9

DETECT NEW EEPROM

(OPTION EDIT SCREEN)

HEX

1-7

SERVICE INFORMATION FOR EEPROM

1. AUDIO PROGRAM

Download program file name must be MICOM_CM9540_YYMMDDX.HEX

If security program (Water Wall) is activated on your PC, you must save the file to the USB storage device and

disable the security software, then download the file to your set. Downloading file proceeds in the same way at

USB1 function and USB2 function.

Caution: When downloading the file, you should neither unplug the USB device, change to the other function,

nor power off the device. USB device must be unplugged when the downloading process is completed.

ON VFD DISPLAY SCREEN

NO USB

↓← Insert USB device at USB function.

↓

MICOM UP

↓

FINISH

↓

Auto POWER OFF

1-8

PROGRAM DOWNLOAD & UPDATE GUIDE

2. CD PROGRAM

Download program file name must be HG480_CM9540_YYMMDDX.bin

If security program (Water Wall) is activated on your PC, you must save the file to the USB storage device and

disable the security software, then download the file to your set. Downloading file proceeds in the same way at

USB1 function and USB2 function.

Caution: When downloading the file, you should neither unplug the USB device, change to the other function,

nor power off the device. USB device must be unplugged when the downloading process is completed.

ON VFD DISPLAY SCREEN

NO USB

↓← Insert USB device at USB function.

↓

MCS UP

↓

SMJ UP

↓

FINISH

↓

Auto POWER OFF

1-9

3. DEMO PROGRAM

Download program file name must be DEMO_DAT.bin

If security program (Water Wall) is activated on your PC, you must save the file to the USB storage device and

disable the security software, then download the file to your set. Downloading file proceeds in the same way at

USB1 function and USB2 function.

Caution: When downloading the file, you should neither unplug the USB device, change to the other function,

nor power off the device. USB device must be unplugged when the downloading process is completed.

ON VFD DISPLAY SCREEN

NO USB

↓← Insert USB device at USB function.

↓

DEMO UP

↓

FINISH

↓

Auto POWER OFF

1-10

4. EQ PROGRAM

Download program file name must be EQ_PRG.BIN

If security program (Water Wall) is activated on your PC, you must save the file to the USB storage device and

disable the security software, then download the file to your set. Downloading file proceeds in the same way at

USB1 function and USB2 function.

Caution: When downloading the file, you should neither unplug the USB device, change to the other function,

nor power off the device. USB device must be unplugged when the downloading process is completed.

ON VFD DISPLAY SCREEN

NO USB

↓← Insert USB device at USB function.

↓

EQ UP

↓

FINISH

↓

Auto POWER OFF

1-11

SPECIFICATIONS

1-12

• GENERAL

Power requirements Refer to the main label.

Power consumption Refer to the main label.

Dimensions (W x H x D) (290 x 349 x 370) mm

Net Weight (Approx.) 5.9 kg

Operating temperature 5 °C to 35 °C (41 °F to 95 °F)

Operating humidity 60 %

Bus Power Supply 5 V 500 mA

• INPUTS

AUX IN 2.0 Vrms (1 kHz, 0 dB), 600 Ω, RCA jack (L, R)

PORT. IN 1.2 Vrms (3.5 mm stereo jack)

MIC 20 mV

• TUNER

FM Tuning Range 87.5 to 108.0 MHz or 87.50 to 108.00 MHz

AM Tuning Range 522 to 1 620 kHz, 520 to 1 710 kHz or 522 to 1 710 kHz

• CD

Frequency Response 40 to 20 000 Hz

Signal-to-noise ratio 75 dB

Dynamic range 80 dB

• AMPLIFIER

Stereo mode 385 W x 2 (THD 20 %)

Surround mode

Front 385 W x 2 (THD 20 %)

Surround 385 W x 2 (THD 20 %)

Subwoofer 385 W x 2 (THD 20 %)

• FRONT SPEAKER

Type 2 Way 2 Speaker

Impedance 6 Ω

Rated Input Power 385 W

Max. Input power 770 W

• SURROUND SPEAKER

Type 1 Way 1 speaker

Impedance 6 Ω

Rated Input Power 385 W

Max. Input power 770 W

Net Dimensions (W x H x D) (425 x 505 x 351) mm

Net Weight 13.2 kg

• SUBWOOFER

Type 1 Way 1 speaker

Impedance 6 Ω

Rated Input Power 385 W

Max. Input power 770 W

Net Dimensions (W x H x D) (425 x 505 x 354) mm

Net Weight 12.7 kg

• Design and specifications are subject to change without notice.

SECTION 2

CABINET & MAIN CHASSIS

CONTENTS

EXPLODED VIEWS ..................................................................................................................................... 2-3

1. CABINET AND MAIN FRAME SECTION (CM9540) ................................................................................ 2-3

2. MECHANISM DECK SECTION (DP17TM2) ............................................................................................ 2-5

3. PACKING ACCESSORY SECTION ......................................................................................................... 2-7

4. SPEAKER SECTION ................................................................................................................................ 2-8

2-1

MEMO

2-2

EXPLODED VIEWS

1. CABINET AND MAIN FRAME SECTION (CM9540)

300

MAIN

SMPS

266

A46

267

443

252

251

252

253

A42

A47

443

268

270

269

272

271

443

B/T

A52

CABLE4

A44

259

MIC & PTB

443

CABLE3

443

CABLE1

FRONT

CABLE2

291

NFC Tag

A43

A56

NOTES) THE EXCLAMATION POINT WITHIN AN

EQUILATERAL TRIANGLE IS INTENDED

TO ALERT THE SERVICE PERSONNEL

TO THE PRESENCE OF IMPORTANT

SAFETY INFORMATION IN SERVICE

LITERATURE.

2. MECHANISM DECK SECTION (DP17TM2)

1026

1439

A001

1002

1005

1001

1049

1437

1024

1030

1024

1043

1045

A005

A006

1016

1013

1015

1020

1024

1003

1439

1018

1019

1011

1012

1437

1004

801 Owner’s Manual

804 Bag

802 Box

808 Battery

900 Remote Control

825 FM Wire Antenna

803 Packing

826 Filter, Ferrite Core

3. PACKING ACCESSORY SECTION

LED

SUB

LED

MAIN

A60L

A61

A62

651

652

4. SPEAKER SECTION

4-1. FRONT SPEAKER (CMS9540F)

• LEFT SPEAKER

LED

SUB

LED

MAIN

A60R

A61

A62

651

652

FRONT SPEAKER (CMS9540F)

• RIGHT SPEAKER

LED

SUB

LED

MAIN

A91

A90

952

A92

951

836A Rubber Foot (Rear)

836L Rubber Foot (Left)

836R Rubber Foot (Right)

4-2. SUBWOOFER SPEAKER (CMS9540W)

SECTION 3

ELECTRICAL

CONTENTS

ONE POINT REPAIR GUIDE ............................................................................................................................ 3-2

1. NO POWER ............................................................................................................................................ 3-2

2. NO BOOTING WHEN POWER ON THE SET ....................................................................................... 3-4

3. VFD IS NOT DISPLAYED WHEN POWER ON THE SET ..................................................................... 3-5

4. NO BOOTING IN CD/USB FUNCTION .................................................................................................. 3-6

5. NO OPERATION OF MD (DRIVING THE SERVO MOTORS) ............................................................ 3-11

6. NO SOUND .......................................................................................................................................... 3-16

7. AUDIO OUTPUT IS SMALL OR NO AUDIO OUTPUT ........................................................................ 3-22

8. NO POWER ON (STANDBY LED IS BLINKING) ................................................................................ 3-23

9. SPEAKER NO AUDIO .......................................................................................................................... 3-24

ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................ 3-25

1. POWER SUPPLY ON SMPS BOARD ................................................................................................. 3-25

2. SYSTEM PART .................................................................................................................................... 3-29

3. NO AUDIO PART ................................................................................................................................. 3-30

4. NO LIGHTING (WOOFER SPEAKER) ................................................................................................. 3-35

WAVEFORMS OF MAJOR CHECK POINT ................................................................................................... 3-36

WIRING DIAGRAM ......................................................................................................................................... 3-41

BLOCK DIAGRAMS ........................................................................................................................................ 3-43

1. SMPS BLOCK DIAGRAM..................................................................................................................... 3-43

2. MAIN SYSTEM BLOCK DIAGRAM ...................................................................................................... 3-45

3. MAIN POWER BLOCK DIAGRAM ....................................................................................................... 3-47

CIRCUIT DIAGRAMS ...................................................................................................................................... 3-49

1. SMPS - POWER #1 CIRCUIT DIAGRAM ............................................................................................ 3-49

2. SMPS - POWER #2 CIRCUIT DIAGRAM ............................................................................................ 3-51

3. MAIN - CD DSP CIRCUIT DIAGRAM .................................................................................................. 3-53

4. MAIN - RF / SERVO CIRCUIT DIAGRAM ........................................................................................... 3-55

5. MAIN - ADC / PWM CIRCUIT DIAGRAM ............................................................................................ 3-57

6. MAIN - AMP CIRCUIT DIAGRAM ........................................................................................................ 3-59

7. FRONT VOLUME CIRCUIT DIAGRAM ................................................................................................ 3-61

8. MIC & PORTABLE CIRCUIT DIAGRAM .............................................................................................. 3-63

9. FRONT SPEAKER MAIN CIRCUIT DIAGRAM .................................................................................... 3-65

10. FRONT SPEAKER SUB CIRCUIT DIAGRAM ..................................................................................... 3-67

11. WOOFER SPEAKER MAIN CIRCUIT DIAGRAM ................................................................................ 3-69

12. WOOFER SPEAKER SUB CIRCUIT DIAGRAM .................................................................................. 3-71

CIRCUIT VOLTAGE CHART .......................................................................................................................... 3-73

1. CONNECTORS .................................................................................................................................... 3-73

2. CAPACITORS....................................................................................................................................... 3-74

PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-75

1. SMPS P.C.BOARD ............................................................................................................................... 3-75

2. MAIN P.C.BOARD ................................................................................................................................ 3-79

3. FRONT VOLUME P.C.BOARD ............................................................................................................ 3-83

4. MIC & PORTABLE P.C.BOARD ........................................................................................................... 3-85

5. FRONT SPEAKER MAIN P.C.BOARD ................................................................................................ 3-85

6. FRONT SPEAKER SUB P.C.BOARD .................................................................................................. 3-85

7. WOOFER SPEAKER MAIN P.C.BOARD ............................................................................................. 3-87

8. WOOFER SPEAKER SUB P.C.BOARD .............................................................................................. 3-87

3-1

3-2

ONE POINT REPAIR GUIDE

1. NO POWER

If the unit doesn’t work by no power problem, repair the set according to the following

guide.

1-1. FUSE / BRIDGE DIODE / THERMISTOR

1-1-1. Solution

Please check and replace F901, BD901, TH900, TH901 on SMPS board.

1-1-2. How to troubleshoot (Countermeasure)

1) Check if the fuse F901 is open or short-circuit.

2) Check if the bridge diode BD901 is short-circuit by over current with a digital multi meter.

3) Check if the NTC thermistor TH900, TH901 is normal or open.

1-1-3. Service hint (Any picture / Remark)

< F901 >

If F901 is not short-circuit,

replace it with a same

speciﬁ cations one.

< TH900, TH901 >

If TH900, TH901 is open,

replace it with a new one.

< BD901 >

If BD901 is short-circuit,

replace it with a new one.

T12AH/250V

(12A 250V)

GND

FH901

FH902

VR900

FNR-14K681T

C90

1uF

/550V

CM901

0.33uF/275V

CM902

0.33uF/275V

CM903

0.22uF/275V

PN901

GP390-02P-TS

LF901

9FL

25x15

HS906

@Opti

TP13 TP14

TP15

TP16

TP20TP12

C901

470pF/250VAC

C902

C903

1000pF/250VAC

C909

1000pF/250VAC

R904

R903

R902

R901

R905

R906

R9E1

R9E2

R9E3

F901

J902

J901

J903

J904

TH900

5ohm

TH901

5ohm

TH902

READY

BD901

D10XB60

600V/10A

R-PART:EBG61545701

R:EAE62524901

3-3

ONE POINT REPAIR GUIDE

NO POWER

If the unit doesn’t work by no ±PVDD problem, repair the set according to the following

guide.

1-2. NO AMP POWER

1-2-1. Solution

Please check and replace F911, Q905, Q906 on SMPS board.

1-2-2. How to troubleshoot (Countermeasure)

1) Check if the fuse F901 is open or short-circuit.

2) Check the Drain-Source or Drain-Gate, Gate-Source Resistance of Q905, Q906 with a digital multi-meter.

 If it is short condition, it’s destroyed. Replace it with a new one.

(Please replace 2 FET at the same time although several FET is OK)

1-2-3. Service hint (Any picture / Remark)

D932

SMFB14

D934

SMFB14

D935

SMFB14

D921

D922

1SS355

D926

SMFB14

ZD912

READY

ZD904

BZX84-C16

ZD915

BZX84-C10

ZD917

READY

C943

22nF

C935

470nF

/50V

C977

10nF

C978

102PF

C979

102PF

C982

C938

68PF

1KV/125C

C933

10nF

C960 1u

C972

READY

C932

READY

GND

PFC_OUT

380V

PFC_TH

TH912

TH913

TH914

PFC_PTC_SMD

FH912

FH911

P.GND

T902

CM9720 PULSE

IC902

ICE1HS01G-1

FMIN

VINS

GND

VCC

Q905

IPA60R190E6

Q906

IPA60R190E6

F911

6.3A/250V

TP32

TP38

TP39

TP41

TP42

TP43

TP46

TP47

TP48

TP60

TP61

TP62

TP63

TP64

TP65

PC90

R980

R944

R945

R942

R9A3

R9A6

R941

24K

R950

10K

R949

R9B4

0OHM

R9A7

150

R9B9

10K

R9B7

100

R9B8

4.7

R990

10K

R986

100

R988

4.7

R992

3.3

R993

3.3

R9A8

50X15

HS904

BC915

UBW2012-121F

BC911

UBW2012-121F

C934

0.039uF

1250V

C992

READY

C993

READY

T903

R927

2.7K

R951

12K

R9C4

C940

10nF

C939

22nF

C942

100nF

R951:24K=> 65KHZ

R951:20K=> 70KHZ

22k VINS :285V

ON/OFF:11.3~12.7V

FBH:4.5V OVERLOAD

Fixed Blanking Time:20ms

VCSL:0.8V

VCSH:1.63V

HS905 H/S

27T/8T:2T

230uH:65uH

25deg >330ohm

Vab:5V

Vth:1.25V

MARK:G2

Ivcc:5.8mA

70deg->2.2kohm

24k VINS :260V

< F911 >

If F911 is not short-circuit,

replace it with a same speciﬁ cations one.

< Q905, Q906 >

If Q905, Q906 is short-circuit,

replace it with a new one.

3-4

ONE POINT REPAIR GUIDE

2. NO BOOTING WHEN POWER ON THE SET

The set doesn’t work when press the power button on the front board or the remote

control.

2-1. MICOM (IC501)

2-1-1. Solution

Please check and replace IC501 on MAIN board.

2-1-2. How to troubleshoot (Countermeasure)

1) Check the 5.6 VA (CN106) and DVCC 3.3 V(IC505) in standby mode.

 If there is no 5.6 VA, check the SMPS and if doesn’t appear 3.3 V, check IC505.

2) Check 5.6 VA, +12 V, FL+, FL-, an +39 V when power on the set.

If the set doesn’t work regardless of what the KEY2 changes high to low while pressing the power button.

X500 and X501 work normally but, if you can not power on the set, replace the IC501 with a new one on

the main board.

2-1-3. Service hint (Any picture / Remark)

w~yj{ys

Oy\m^P

rlX

O X]P

\WW

OY[to¡P

\WX

OZYU^]_ro¡P

< MAIN board top view >

3-5

kpnZWXG} mk

{w ZWYSG

{w ZWZSG

{wZW[

xZWX xZW[xZWZ

yZY^O{w ZW[P

xZWXGl  

G

ZW} T

j G G  SG G  GGG

GU

  GGGG U

< MAIN board top view >

ONE POINT REPAIR GUIDE

3. VFD IS NOT DISPLAYED WHEN POWER ON THE SET

When power on the set, any icons or characters on VFD are not displayed.

3-1. VFD (DIG300)

3-1-1. Solution

Please check and replace DIG300 on FRONT board.

3-1-2. How to troubleshoot (Countermeasure)

1) Check if 39V, FL+ and FL-are output from SMPS to VFD via the main board.

2) Check if the IC101 outputs VFD_RST, VFD_CLK, VFD_STB, and VFD_STB to the front board.

3) Check if the VFD grid current amplifier circuit (Q301, Q303) on the front board.

Check the drive signal to the transistor’s base.

 If the control signals from VFD (DGND_2, VH, VDD) isn’t output, replace VFD with a new one.

 If the transistor doesn’t work, replace it.

3-1-3. Service hint (Any picture / Remark)

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