Alto HPA4 Schematic

Service Manual

Model: HPA4

6-Channel HEADPHONE AMPLIFIER

www.altoproaudio.com

Version: 1. 1

CONTENTS

1. Specification ─────────── 2

2. Block Diag ram ─────────── 1

3. Schematic Diagram ─────────── 3

4. Printed Circuit Board ─────────── 6

5. Wiring Diagram ─────────── 1

6. Test Procedure ─────────── 0

7. Electrical Parts List ─────────── 9

8. Exploded Views & Mechanical Parts Li st ─── 2

9. Troubleshooting ─────────── 0

10. Notes ─────────── 0

1.Specifications

1.1

AUDIO INPUT

MAIN input

Connectors XLR and 1/4” jack
Type HF filtered, servo balanced input
Impedance 40kOhms balanced, 20kOhms unbalanced
Max.input level +21dBu balanced and unbalanced
CMRR typ.40dB, >55dB@1kHz

AUX IN and DIRECT IN input

Connectors 1/4”TRS(tip=left, ring=right, sleeve=ground)
Type unbalanced
Impedance >15kOhms unbalanced
Max.input level +21dBu unbalanced
CMRR typ.40dB, >55dB@1kHz

AUDIO OUTPUT

Connectors XLR and 1/4”jack
Type balanced/unbalanced
Impedance dependent on the input impedance
Max.input level +21dBu balanced and unbalanced

SYSTEM SPECIFICATIONS

Frequency response 10Hz to 50kHz, +/-3dB
Noise >90dB, unweighted, 22Hz to 22kHz (>95dB@+4dBu)
THD 0.005% typ.@+4dBu, 1kHz, Gain 1

POWER AMPLIFIER

Max.output power +21dBm
Min.output impedance 100Ohms

FUNCTION CONTROLS

Input level variable
Balanced per channel mix between aux and main signal
Output level per channel variable
Treble +15/-15
Bass +15/-15

FUNCTION SWITCHES

Left mute mute the left signal of the respective channel
Right mute mute the right signal of the respective channel
Mode switches channel to mono

INDICATORS

Input level 8-digit LED display:-18/-12/-6/0/+6/+12/+18dBu/CLIP
Output level 8-digit LED display:-18/-12/-6/0/+6/+12/+18dBu/CLIP

POWER SU PPLY

1.2

Mains voltage USA/Canada 120V∼, 60Hz

Power consumption 40W
Fuse 95-120V∼:T315mA L/210-240V∼:T200mA L

Mains connecti on standard IEC receptacle

PHYSICAL

Dimension 483(W)x217(D)x44(H)mm(19”x8.54”x1.7”)
Net weight 2.9kg(6.39lb)

U.K./Australia 240V∼, 50Hz
Europe 230V∼, 50Hz
general export model 95-120V∼, 210-240V∼, 50-60Hz

D

2

C

B

A

X9

3c5e1a

4d

4321

2b

POWER SUPPLY

VOLTAGE REGULATOR

213

4 X7

-15VDC

+15VDC

RIGHT

MASTER OUTPUT

X8

3c5e1a

4d

2b

AC 110/220V INPUT

LEFT

MASTER OUTPUT

213

4 X5

X6

3c5e1a

4d

2b

SIGNAL

PRESENT

X10

CH1 REAR OUTPUT1

3c5e1a

4d

2b

G

SIGNAL

SENSE

G

SIGNAL

SENSE

CH1 REAR OUTPUT2

SIGNAL

PRESENT

LEFT

1

2

3

1

L-MUTE

X3

3c5e1a

4d

2b

2

3

RIGHT

1

2

R-MUTE

CH1 FRONT OUTPUT

~ ~

TO STAGES 2-4

3

Block Diagram

213

X1

3c5e1a4d2b

X2

MASTER LEVEL

213

X3

3c5e1a4d2b

X4

3c5e1a4d2b

3c5e1a4d2b

BASS/TREBLE

MONO/STEREO

HEADPHONE LEVEL

BALANCED

BASS/TREBLE

1 2 3 4

LEFT

MASTER INPUT

D

RIGHT

MASTER INPUT

X1

C

DIRECT IN

B

X2

AUX INPUT

A

D

3.1

C

B

A

GR

LD30GRLD31GRLD32GRLD33GRLD34GRLD35

(-24)

(-18)

R131

HR

TR7

470R 1/4W

+15V

87654321

+15V

+15V

+15V

+15V

R124

R130

R123

R129

R122

R128

R121

R127

R120

2M00

R117

470R 1/4W

2M00

R116

470R 1/4W

2M00

R115

470R 1/4W

2M00

R114

470R 1/4W

2M00

R113

14

13

IC9D

IC9C

LM339

LM339

1M00

HR

TR6

1M00

HR

TR5

1M00

HR

TR4

1M00

HR

TR3

1M00

8

9

R146

110R

9

R145

110R

9

R144

110R

9

R143

110R

9

R142

110R

10

11

R156

100R

LD24GRLD25GRLD26GRLD27GRLD28GRLD29

(-24)

14

13

IC7D

IC7C

LM339

LM339

8

10

11

R155

100R

LD18GRLD19GRLD20GRLD21GRLD22GRLD23

(-24)

14

13

IC5D

IC5C

LM339

LM339

8

10

11

R154

100R

LD12GRLD13GRLD14GRLD15GRLD16GRLD17

(-24)

14

13

IC3D

IC3C

LM339

LM339

8

10

11

R153

100R

LD6GRLD7GRLD8GRLD9GRLD10GRLD11

(-24)

14

13

IC1D

IC1C

LM339

LM339

8

10

11

R152

100R

(-12)

1

2

IC9A

IC9B

LM339

LM339

6

7

5

4

R161

R166

200R

(-18)

1

6

7

R160

200R

(-18)

1

6

7

R159

200R

(-18)

1

6

7

R158

200R

(-18)

1

6

7

R157

200R

R171

402R

(-12)

2

IC7A

IC7B

LM339

LM339

5

4

R165

R170

402R

(-12)

2

IC5A

IC5B

LM339

LM339

5

4

R164

R169

402R

(-12)

2

IC3A

IC3B

LM339

LM339

5

4

R163

R168

402R

(-12)

2

IC1A

IC1B

LM339

LM339

5

4

R162

R167

402R

(0)

(-6)

14

IC10C

LM339

8

9

R151

806R

(-6)

14

IC8C

LM339

8

9

R150

806R

(-6)

14

IC6C

LM339

8

9

R149

806R

(-6)

14

IC4C

LM339

8

9

R148

806R

(-6)

14

IC2C

LM339

8

9

R147

806R

(+6)

1

13

IC10D

LM339

6

7

10

11

1K58

R141

3K24

GR

(0)

(+6)

1

13

IC8D

LM339

6

7

10

11

1K58

R140

3K24

GR

(0)

(+6)

1

13

IC6D

LM339

6

7

10

11

1K58

R139

3K24

GR

(0)

(+6)

1

13

IC4D

LM339

6

7

10

11

1K58

R138

3K24

GR

(0)

(+6)

1

13

IC2D

LM339

6

7

10

11

1K58

R137

3K24

IC10B

IC8B

IC6B

IC4B

IC2B

LD5

LM339

LD4

LM339

LD3

LM339

LD2

LM339

LD1

LM339

LD40

RED

YEL

(+18)

(+12)

-15V+15V

C75

OUTPUT4

8K06

R176

RED

(+18)

OUTPUT3

8K06

R175

RED

(+18)

OUTPUT2

8K06

R174

RED

(+18)

OUTPUT1

8K06

R173

RED

(+18)

INPUT

8K06

R172

-15V+15V

-15V+15V

-15V+15V

-15V+15V

100nF

R192

1K00

1uF

C84

-15V

C74

100nF

R191

1K00

1uF

C83

-15V

C70

100nF

R190

1K00

1uF

C82

-15V

C64

100nF

R189

1K00

1uF

C81

-15V

C61

100nF

R188

1K00

1uF

C80

-15V

2

IC10A

LM339

5

4

6K34

R136

LD39

YEL

(+12)

2

IC8A

LM339

5

4

6K34

R135

LD38

YEL

(+12)

2

IC6A

LM339

5

4

6K34

R134

LD37

YEL

(+12)

2

IC4A

LM339

5

4

6K34

R133

LD36

YEL

(+12)

2

IC2A

LM339

5

4

6K34

R132

7

IC13B

4580

R186 12K7

5

6

D10

DA204K

R185

12K7

D5

BAS16

FP BOARD

1

IC13A

4580

HPA4FP2.SCH

R184 12K7

3

2

D9

DA204K

312

IC10E

R183

12K7

D4

BAS16

7

IC12B

4580

R182 12K7

5

6

D8

DA204K

R181

12K7

D3

BAS16

1

IC12A

4580

R180 12K7

3

2

D7

DA204K

R179

12K7

D2

BAS16

IC11B

LV DISPLAY CH1 LV DISPLAY CH2 LV DISPLAY CH3 LV DISPLAY CH4

4580

7

LM339

312

IC9E

LM339

312

IC8E

LM339

312

IC7E

LM339

312

IC6E

LM339

312

IC5E

LM339

312

IC4E

LM339

312

IC3E

LM339

312

IC2E

LM339

312

IC1E

LM339

84

IC13C

4580

84

IC12C

4580

R178 12K7

5

6

D6

DA204K

R177

12K7

D1

BAS16

84

IC11C

+15V

84

IC14C

4580

4580

21 of

C.C.LIN

RevisionModel No:

Drawn By:

Sheet

HPA4 VER030106

6-Jan-2003

HPA4FP.Sch

ALTO : HPA4 FP DISPLAY BOARD

A3

Titel

Size

File:

Date:

C73

100nF

+15V

C72

100nF

+15V

C71

100nF

+15V

C69

100nF

+15V

C68

100nF

+15V

C67

100nF

+15V

C66

100nF

+15V

C65

100nF

+15V

C63

100nF

+15V

C62

100nF

+15V

R187

22R

-15V

+15V

+15V

R126

R119

R125

R118

470R 1/4W

2M00

470R 1/4W

2M00

R58

10K0

R57

10K0

LED11

P

22E85L

LED9

P

22E85L

GR

456

SW9B

GR

456

SW3B

LED8

P

22E85L

LED4

P

22E85L

YEL

456

SW11B

YEL

456

SW5B

C

LED7

P

22E85L

LED3

P

22E85L

LED5

P

22E85L

LED1

P

22E85L

YEL

456

SW7B

YEL

456

SW1B

LED6

HR

TR2

R112

1M00

YEL

456

SW8B

LED2

HR

TR1

R111

1M00

YEL

456

SW2B

D

YEL

456

SW10B

YEL

456

SW4B

LED12

P

22E85L

LED10

P

22E85L

GR

456

SW12B

GR

456

SW6B

P

22E85L

P

22E85L

-15V -15V

C79

220uF/4V

(VOL CTRL)

VR1B

A20K

R110

5K11

MAIN-IN_L

A

R100

20K0

7

IC14B

C77

47P

4580

5

6

1 2 3 4 5 6 7 8

R99

20K0

C78

220uF/4V

INPUT_L

INPUT_R

(VOL CTRL)

VR1A

A20K

3c5e1a4d2b

X1

SCJ-0658-1-Y

B

GND2

( DIRECT IN )

5K11

R109

MAIN-IN_R

1

IC14A

4580

C76

47P

3

2

D

3.2

C

B

A

1234567891011

C59

100nF

C60

100nF

IC22C

-15V

+15V

IC21C

IC20C

IC19C

4580

4580

4580

4580

R103

5K11

4 8

4 8

-15V

4 8

4 8

CH2-INPUT_R

123

OUT 2

3c5e1a4d2b

CH2-OUTPUT_L

CH2-OUTPUT_R

SW6A

22E85L

(MO/ST)

X5

R104

5K11

SCJ-0658-1-Y

CH2-INPUT_L

IC18C

+15V

IC17C

IC16C

IC15C

4580

4 8

4580

4 8

4580

4 8

4580

4 8

87654321

OUT 1

X3

SCJ-0658-1-Y

R101

5K11

3c5e1a4d2b

CH1-INPUT_R

123

CH1-OUTPUT_R

SW3A

22E85L

CH1-OUTPUT_L

(MO/ST)

R102

5K11

GND2

CH1-INPUT_L

R37

10K0

LV DISPLAY CH1

R38

10K0

CN1

MAIN-IN_L

MAIN-IN_R

CH1-INPUT_L

CH1-INPUT_R

GND2

LV DISPLAY CH2

R39

R52

10K0

10K0

CH2-INPUT_L

CH2-INPUT_R

CH1-OUTPUT_L

CH1-OUTPUT_R

CH3-INPUT_R

123

R105

5K11

12

CH2-OUTPUT_L

CH2-OUTPUT_R

3c5e1a4d2b

CH3-OUTPUT_R

SW9A

12P-2.0

OUT 3

CH3-OUTPUT_L

22E85L

(MO/ST)

1234567891011

CN2

+15V

CH3-INPUT_L

CH3-INPUT_R

CH3-OUTPUT_L

CH3-OUTPUT_R

X7

SCJ-0658-1-Y

GND2

CH3-INPUT_L

R53

R54

R106

10K0

5K11

CH4-INPUT_L

CH4-INPUT_R

LV DISPLAY CH3

10K0

12

12P-2.0

-15V

CH4-OUTPUT_L

CH4-OUTPUT_R

CN3

PWR LED

R107

5K11

GND2

+15V

R0

2
1

CON2

CH4-INPUT_R

123

1K2

OUT 4

3c5e1a4d2b

CH4-OUTPUT_L

CH4-OUTPUT_R

SW12A

22E85L

(MO/ST)

ALTO : HPA4 FP BOARD

Titel

X9

SCJ-0658-1-Y

GND2

CH4-INPUT_L

R55

R108

10K0

5K11

RevisionModel No:

HPA4 VER030106

A3

Size

LV DISPLAY CH4

R56

10K0

21 of

C.C.LIN

Drawn By:

Sheet

7-Jan-2003

HPA4FP2.Sch

File:

Date:

C7

220uF/10V

1M50

R83

10K0

R33

B50K

C27

1N8

VR4A

C3

220uF/10V

(VOLUME CTRL)

A100K

VR3B

10K0

R25

VR2A

B10K

15K0

R1

24K9

R75

C51

C35

C19

R26

123

R91

1

IC16A

20P

2

22N

R59

5K62

R8

15K0

1

22P

2

10K0

R2

B50K

VR5A

15K0

123

SW1A

22E85L

(R/MUTE)

20K0

C8

220uF/10V

R63

5K62

1M50

4580

R84

C52

B50K

VR4B

20P

10K0

24K9

R34

R76

C28

1N8

C36

22N

3

47N

C43

R60

R9

C5

220uF/10V

IC15A

4580

VR3A

A100K

3

R27

10K0

VR2B

B10K

(BALANCE)

R3

15K0

IC16B

6

SW2A

22E85L

R93

7

(L/MUTE)

20K0

R64

5K62

4580

5

47N

B50K

C44

VR5B

5K62

15K0

7

IC15B

4580

C21

22P

(VOLUME CTRL)

VR7B

5

6

R28

10K0

R29

10K0

R4

R5

15K0

15K0

B50K

VR8A

A100K

C4

C9

1M50

R85

10K0

R35

C29

220uF/10V

VR6A

220uF/10V

C53

24K9

R77

1N8

C37

B10K

123

IC18A

20P

2

22N

R61

R10

C20

22P

2

R30

10K0

123

SW4A

22E85L

C45

IC17A

(R/MUTE)

C10

220uF/10V

R65

5K62

1M50

4580

R86

C54

20P

10K0

24K9

R36

R78

47N

B50K

C30

1N8

C38

22N

VR8B

R62

R11

C6

220uF/10V

4580

VR7A

A100K

R31

10K0

VR6B

B10K

(BALANCE)

R7

15K0

R92

20K0

1

3

B50K

VR9A

5K62

15K0

1

3

R6

15K0

IC18B

6

SW5A

22E85L

R94

20K0

7

(L/MUTE)

R70

5K62

4580

5

47N

B50K

C46

VR9B

5K62

15K0

7

IC17B

4580

C22

22P

(VOLUME CTRL)

VR11B

5

6

R32

10K0

R40

10K0

R12

R13

15K0

15K0

B50K

VR12A

A100K

1M50

R87

10K0

R48

C11

C15

220uF/10V

24K9

R79

C31

1N8

220uF/10V

VR10A

B10K

C55

C39

C23

R41

123

R95

1

IC20A

20P

2

22N

R66

5K62

R21

15K0

1

22P

2

10K0

R14

20K0

B50K

VR13A

15K0

123

SW7A

22E85L

(R/MUTE)

C16

220uF/10V

R71

5K62

1M50

4580

R88

C56

B50K

VR12B

20P

10K0

24K9

R49

R80

C32

1N8

C40

22N

3

47N

C47

R67

R22

C13

220uF/10V

IC19A

4580

VR11A

A100K

3

R42

10K0

VR10B

B10K

(BALANCE)

R15

15K0

IC20B

6

SW8A

22E85L

R97

20K0

(L/MUTE)

R72

5K62

7

4580

5

47N

B50K

C48

VR13B

5K62

15K0

7

IC19B

4580

C25

22P

(VOLUME CTRL)

VR15B

5

6

R43

R44

10K0

10K0

R16

R17

15K0

15K0

B50K

VR16A

A100K

1M50

R89

10K0

R50

C12

C17

220uF/10V

24K9

R81

C33

1N8

220uF/10V

VR14A

B10K

C57

C41

C24

R45

123

R96

IC22A

20P

2

22N

R68

5K62

R23

15K0

22P

2

10K0

R18

1

1

20K0

B50K

VR17A

15K0

123

SW10A

22E85L

(R/MUTE)

C18

220uF/10V

R73

5K62

1M50

4580

R90

C58

B50K

VR16B

20P

10K0

24K9

R51

R82

C34

1N8

C42

22N

3

47N

C49

R69

R24

C14

220uF/10V

IC21A

4580

VR15A

A100K

3

R46

10K0

VR14B

B10K

(BALANCE)

R19

15K0

IC22B

6

SW11A

R98

22E85L

20K0

(L/MUTE)

R74

5K62

7

4580

5

47N

B50K

C50

VR17B

5K62

15K0

7

IC21B

4580

C26

22P

5

6

R47

10K0

R20

15K0

C1 220uF/10V

INPUT_R

C2

220uF/10V

INPUT_L

3c5e1a4d2b

X2

SCJ-0658-1-Y

GND2

( AUX IN )

D

3c5e1a4d2b

X4

SCJ-0658-1-Y

GND2

( AUX IN )

C

3c5e1a4d2b

X6

SCJ-0658-1-Y

GND2

( AUX IN )

B

3c5e1a4d2b

X8

SCJ-0658-1-Y

GND2

( AUX IN )

A

1 2 3 4 5 6 7 8

D

3.3

C

B

A

11 of

87654321

MAIN-IN_L

MAIN-IN_R

CH1-INPUT_L

123456789

CN1

CH1-INPUT_R

CH2-INPUT_L

CH1-OUTPUT_L

CH1-OUTPUT_R

CH2-INPUT_R

CH2-OUTPUT_L

CH2-OUTPUT_R

101112

12P-2.0

+15V

CH3-INPUT_L

CH3-INPUT_R

CH3-OUTPUT_L

123456789

CN2

CH4-INPUT_L

CH4-INPUT_R

CH3-OUTPUT_R

CH4-OUTPUT_L

101112

-15V

CH4-OUTPUT_R

12P-2.0

RevisionModel No:

C.C.LIN

Drawn By:

Sheet

TIP : L-CHANNEL

RING:R-CHANNEL

R30

C4

47P

R11 10K0

7

6

R3

5K11

CH2-INPUT_R

CH2-OUTPUT_R

3c5e1a4d2b

3c5e1a4d2b

R31

22R

22R

1

2

IC4B

BA15218

5

HPA4 VER030106

6-Jan-2003

ALTO : HPA4 RP BOARD

A3

Titel

Size

Date:

C36

47/25V

R47

22R

-15V

C34

47/25V

R45

22R

-15V

C32

47/25V

R43

22R

-15V

C30

47/25V

R41

22R

-15V

C23

100nF

-15V

HPA4RP.Sch

File:

CH4-OUTPUT_R

3c5e1a4d2b

3c5e1a4d2b

R38

22R

1

3

2

IC8B

BA15218

5

R39

OUT 4

22R

IC8A

R40

BA15218

47P

C11

X8

SCJ-0658-1-Y

X7

22RR8

R24 10K0

6

5K11

CH4-INPUT_L

SCJ-0658-1-Y

7

5

CH4-OUTPUT_L

1

3

2

IC9B

BA15218

IC9A

BA15218

+15V

+15V

+15V

+15V

+15V

C35

47/25V

R48

C33

47/25V

R46

C31

47/25V

R44

C29

47/25V

R42

84

22R

84

84

22R

84

84

22R

84

84

22R

84

C24

100nF

84

IC11C

IC10C

IC9C

IC8C

IC7C

IC6C

IC5C

IC4C

IC1C

BA15218

BA15218

BA15218

BA15218

BA15218

BA15218

BA15218

BA15218

4580

OUT 2

X4

CH2-OUTPUT_L

SCJ-0658-1-Y

X3

SCJ-0658-1-Y

R32

22RR4

R29

22R

1

IC4A

BA15218

R12 10K0

47P

3

C3

2

7

IC5B

BA15218

5

6

5K11

CH2-INPUT_L

3

IC5A

BA15218

TIP : L-CHANNEL

RING:R-CHANNEL

R33

C8

47P

R17 10K0

7

6

R5

5K11

CH3-INPUT_R

CH3-OUTPUT_R

3c5e1a4d2b

3c5e1a4d2b

R34

22R

22R

1

2

IC6B

BA15218

5

OUT 3

X6

CH3-OUTPUT_L

SCJ-0658-1-Y

X5

SCJ-0658-1-Y

R36

R35

22RR6

22R

1

IC6A

BA15218

R18 10K0

47P

3

C7

2

7

IC7B

BA15218

5

6

5K11

CH3-INPUT_L

3

IC7A

BA15218

TIP : L-CHANNEL

RING:R-CHANNEL

R37

C12

47P

R23 10K0

6

R7

5K11

CH4-INPUT_R

22R

7

OUT 1

TIP : L-CHANNEL

RING:R-CHANNEL

R25

C2

47P

R9 10K0

7

6

R1

5K11

CH1-INPUT_R

CH1-OUTPUT_R

3c5e1a4d2b

3c5e1a4d2b

R26

22R

22R

1

2

IC10B

BA15218

5

X2

CH1-OUTPUT_L

SCJ-0658-1-Y

X1

SCJ-0658-1-Y

R28

R27

22RR2

22R

IC10A

BA15218

47P

3

C1

1

IC11A

BA15218

R10 10K0

3

2

7

IC11B

BA15218

5

6

C14

20P

R16

10K0

R13

10K0

MAIN-IN_L

7

R50

20K0

IC1B

4580

C16

20P

R49

20K0

5

6

C13

20P

R15

10K0

C5

C6

47P

R14

10K0

R21

47P

10K0

R19

10K0

MAIN-IN_R

1

R52

20K0

IC1A

4580

R51

20K0

3

2

C15

20P

R22

10K0

C9

C10

47P

47P

R20

10K0

IC2

C25

C19

C17

+15V

7815

1000/35V

100nF

100nF

TT4

C22

100nF

C27

10/50V

CN3

3P-3.9

TT5

TT3

123

-15V

C21

100nF

C28

10/50V

IC3

7915

C26

1000/35V

BD1

RB154

C20

100nF

C18

100nF

TP1

GND

5K11

213

213

MAIN IN R

B

X15

JY-5030-030G

4

213

X12

JY6351G-02

3c5e1a4d2b

213

3c5e1a4d2b

CH1-INPUT_L

D

X9

JY-5042-030G

X11

JY6351G-02

C

X10

JY-5042-030G

MAIN IN L

X13

JY6351G-02

3c5e1a4d2b

4

X16

JY-5030-030G

MAIN OUT L

A

X14

JY6351G-02

3c5e1a4d2b

1 2 3 4 5 6 7 8

MAIN OUT R