Alto MS1 Service Manual

MODEL: MS1

CONTENT

1. INTRODUCTION.................................................................... ..........1

2. TECHNICAL SPECIFICATION ........................................................1

3. BLOCK DIAGRAM..........................................................................2

4. SCHEMATIC DIAGRAM..................................................................3

5. PCB LAYOUT..................................................................................4

6. TEST PROCEDURE........................................................................5

7. EXPLODED VIEW & MECHANICAL PARTS LIST.........................15

8. BOM ..............................................................................................17

z 16 effects preset

1. INTRODUCTION

2. TECHNIACAL SPECIFICATION

- 1 -

z 2-channel input and output connectors are compatible with balanced JACK
z Front panel LED indicator for clip and power on
z Accurate level control

Connectors 1/4”jack
Type RF filtered, servo balanced input

AUDIO INPUT

Impedance 30 Kohm balanced, 22 Kohm unbalanced
Max. input level +26 dBu balanced and Unbalanced
CMRR Typ. 40dB,>55dB@1 kHz
Connectors 1/4” jack
Type Balanced

AUDIO OUTPUT

Min. output impedance 100 Ohm
Max. output level +26 dBu balanced
Frequency response 10Hz to 30kHz, +/-1dB(FLAT)

SYSTEM

S/N >110dB, unweighted, 22Hz to 22kHz

SPECIFICATIONS

THD 0.005% typ.@ 0 dBu, 1khz, (unity gain), FLAT

INDICATORS Input level CLIP LED display: +7dBu

AC adaptor USA/Canada 120V~, 60Hz
U.K./Australia 240v~, 50Hz

POWER SUPPLY

Europe 230V~, 50Hz
Power consumption 5W
Dimension 130(W)×117(D)×45(H)mm(5.1”×4.6” ×1.7”)

PHYSICAL

Net weight 0.8kg

D

3. BLOCK DIAGRAM

- 2 -

4

C

B

A

CLIP

J2

12345

OUTPUT LCH

6

J4

12345

OUTPUT RCH

6

G

-12V

5

6

321

SIGNAL SENSE

SW1

3

4

4BIT ENCODER

1

2

+12V

12345

J1

ENCODER 4BIT CONTROL

A0 A1 A2 A3

INPUT GAIN

6

INPUTLCH

12345

J3

6

INPUT RCH

AC ADAPTOR

AC 15V 200mA INPUT

A0 A1 A2 A3

+12VDC

-12VDC

1 2 34

POWER SUPPLY

D

C

B

A

B

4. SCHEMATIC DIAGRAM

- 3 -

connect to J5 -1

CLIP

LED2

RED

R72

0R 1/4W

LED1

SW1

123

100K

R42

5

100K

R43

C

6

100K

R44

C38

22P

288S0366

4

100K

R45

D

-VCC

+VCC

8

D3

1N5817

C44

220UF/25V

D4

1N5817

-VCC

C45

220UF/25V

connect to J5 -2

R70

3

C15

0.1u c er

+12V

GND

2

7654321

Vin

1

U9

LM7812CT

D1

1N4002

C13

0.1u

123

S1

DJ-005A

1

U8

C42

1000UF/35V

3

C16

0.1u c er

GND

2

LM7912CT

C43

1000UF/35V

D2

C14

0.1u

-12V

Vin

1N4002

+VCC

6

J2

LJB0661-6

R58

100 1/4W

1M

R69

1M

R68

1M

R67

1M

A0A1A2

A3

R63

12345

C34

R62

51K

C63

22P

C33 47U/25V

R21

10.0K

51K

47U/25V

R59

100 1/4W

C69

0.1u c er

R22

10.0K

-VCC

C68

1.0U

C67

1.0U

C66

1.0U

C65

1.0U

6

1

2

J5

CON2

J4

A0~A3:ON=+VCC,OFF=-VCC,DELAY=0.1-1S

1.5K

R17

R71

+VCC

1

3

2

C70

0.1u c er
C48

8 4

+VCC

C2E

3

B

Q2

2SC1815

1

6.8K

2.2U/25V

Q1

2SC1815

C2E

3

B

1

R31

4.7K

LJB0661-6

12345

C41

47U/25V

R65

51K

C64

22P

C40 47U/25V

R60

100 1/4W

7

R24

10.0K

A

+VCC

connect to J6 -1connect to J6 -2

POWER

R73

4.7K 1/4W

RED

R66

51K

R61

100 1/4W

R25

10.0K

-VCC

1

2

J6

CON2

7

U7B

MC33078

5

6

12V 1W

U6B

R19

3.74K

C62

C61

C39

C26

10P

C4

1

C24

0.1u c er

C28

84

3.74K

U6A

+VCC

C60

C59

C31

C2510P

R35

C3

R18

C23

0.1u cer

1

-VCC

3

R12

1.10K
C7

13

VR1A

2

10KB

-VCC

R8

C6 22P

ZD3

22P

12V 1W

7.50K

2

C30

47U/25V

C29

47U/25V

R11

1.10K

C12

0.1u c er

1

3

2

R7

R1

15.0K

7.50K

C22

U2A

MC33078

R15

C11

MC33078

+VCC

0.1u cer

8 4

6.8K

0.1u c er

+VCC

8 4

U1A

C5

22P

R2

15.0K

ZD4

12V 1W

R39

3

1.0U

1.20K

47U/25V

27nF

C57

1.50K

C21

2

1.0U

C19

1000P

-VCC

C18

MC33078

0.1u c er

+VCC

R47

0.1u c er

2

0.1u c er

0.1u cer

-VCC

R48

7.50K

1

U5A

84

3

2

R51

30.0K

7.50K

1

C27

8 4

3

U4A

MC33078

R37

220.0K

C53

10nF

R33

1.0K

R30

4.7K

1

Fc=30hz

MC33078

C55

R41

100K

0.1u c er

+VCC

C32

-12db/OCT

C20

0.1u c er

-VCC

330P

47U/25V

MC33078

Fc=18K

U7A

C37

CLIP LED LIGHT SET=+6dbU

R57

R55

9.1K

R14

1.10K

R53

20K

-12db/OCT

HIGH Fc=18K,LOW Fc=30HZ IS NOT USED,R74=0R

R74

0R*

C8 22P

TR4

J176

TR3

J176

C10

22P

46

C36

VR1B

5

10KB

C35

47U/25V

R10

7.50K

ZD8

12V 1W

9.1K

7

5

6

6

15.0K

U2B

MC33078

47U/25V

R13

1.10K

7

5

U1B

MC33078

R4

R5

47U/25V

R16

6.8K

R9

7.50K

C9

22P

15.0K

ZD7

MC33078

Fc=30hz

5

6

1.0U

R50

1.0U

C58

1000P

R49

7.5K

47U/25V

R40

1.50K

6

R36

1.20K

27nF

-12db/OCT

7.5K

7

R54

20K

U5B

MC33078

Fc=18K

-12db/OCT

5

6

C56

330P

R52

30.0K

HIGH Fc=18K,LOW Fc=30HZ IS NOT USED,R75=0R

R75

0R*

R46

100K

7

5

U4B

MC33078

R38

220.0K

TR8

J176

C54

10nF

R34

1.0K

R32

4.7K

7

TR7

J176

ZD1

12V 1W

L1

IN-CH2+

6

J1

LJB0661-6

balanced input

L2

FL5R

D

ZD2

FL5R

12345

C17

MC33078

R3

220nF

0.1u c er

8 4

+VCC

U3A

R26

15.0K

C

C47

TR2

J176

2.2U/25V

150.0K

TR1

J176

C46

2.2U/25V
A0 A1 A2 A3

ZD5

12V 1W

L3

6

IN-CH2+

J3

LJB0661-6

balanced input

L4

FL5R

IN-CH2-

ZD6

12V 1W

5

6

R29

30.0K

FL5R

12345

B

C2 100nF

R23

10.0K

U3B

MC33078

R27

150.0K

C50

R6

15.0K

C52

220nF

C49

2.2U/25V

2.2U/25V

A

J176

TR6

J176

1 2 3 4 5 6 78

TR5

A0 A1 A2 A3

12V 1W

IN-CH2-

C1 100nF

-VCC

3

2

R28

30.0K

R20

10.0K

C51

PCB:MS1 Bottom Layer Bttom Overlay Bottom Solder

PCB:MS1 Top Overlay

5. PCB LAYOUT

- 4 -

First: Use VP-7724 to test

6. TEST PROCEDURE

The Finished Products Test

- 5 -

1. Set the encoder to FLAT (encoder setting: 0000), INPUT/OUTPUT use 1/4 TRS BAL jack to co nnect
LCH IN, LCH/RCH OUT, plug in POWER&CLIP LED wires(semi product), the red POWER LED
lights up.

2. Input 1KHZ–6dBu(VP-7724 BAL) signal, then adjust INPUT GAIN VR, when INPUT GAIN VR is
minimum, the output is -20+/-2dbu, distortion<0.03%.

3. Adjust INPUT GAIN V R to maximum, the output i s +20+/-2dbu, distortio n<0.01 %( Please select the
corresponding filter when testing distortion).

4. Adjust INPUT GAIN VR, and set the output to +6.5~+8.5dbu, make sure the CLIP LED lights up
slightly.

5. Adjust INPUT GAIN VR, set the output to 0+/-0.2dbu, and also make sure the scale of GAIN VR at
0dB position.

6. According to the following table to test the frequency response, specifications are the following
(altogether 4*4=16 modes), under FLAT mode, make sure the distortion<0.005%.

7. Adjust the input signal to 1 kHz +10dbu, turn GAIN VR from minimum to maximum, make sure the
distortion will become bigger gradually till clipping (FLAT position).

LCH/RCH OUTPUT SPECIFICATION(Test Frequency dBu)

Corresponding

Function

FLAT 0000 -1.0~+1.0 -0.5~+0.5 -0.5~+0.5 -0.5~+0.5 -1.2~+0.8 -5.0~-3.0
DRUM KICK 0001 +9.5~+11.5 +7.5~+9.5 +6.0~8.0 -0.5~+1.0 -1.2~+0.8 -5.0~-3.0
ANTIRUMBLE 0010 -11.5~-9.5 -3.5~-1.5 -2.5~-0.5 -0.5~+0.5 -1.2~+0.8 -5.0~-3.0
CONCERT HALL 0011 -0.5~+1.5 +5.0~+7.0 +4.5~+6.5 -0.5~+1.0 -1.2~+0.8 -5.0~-3.0
ARENA+SUB 0100 -1.0~+1.0 -1.0~+1.0 -0.5~+0.5 +0.2~+1.5 +4.5~+6.5 +1.5~+3.5
LOUDNESS 0101 +9.5~+11.5 +7.5~+9.5 +6.0~8.0 +0.5~+1.5 +4.5~+6.5 +1.5~+3.5
ROCK&ROLL+SUB 0110 -11.5~-9.5 -3.5~-1.5 -2.5~-0.5 +0.5~+1.5 +4.5~+6.5 +1.5~+3.5
ACOUSTIC 0111 -0.5~+1.5 +5.0~+7.0 +4.5~+6.5 +0.5~+1.5 +4.5~+6.5 +1.5~+3.5
JAZZ CLUB+SUB 1000 -1.0~+1.0 -1.0~+1.0 -0.5~+0.5 -0.5~+0.5 -2.0~-0.5 -9.0~-7.0
VIRTUAL SUB 1001 +9.5~+11.5 +7.5~+9.5 +6.0~8.0 -0.0~+0.8 -2.0~-0.5 -9.0~-7.0
STAGE MONITOR 1010 -11.5~-9.5 -3.5~-1.5 -2.5~-0.5 -0.5~+0.5 -2.0~-0.5 -9.0~-7.0
JAZZ CLUB 1011 -0.5~+1.5 +5.0~+7.0 +4.5~+6.5 -0.0~+0.8 -2.0~-0.5 -9.0~-7.0
CONCERT
HALL+SUB

Encoder Setting

20HZ 70HZ 100HZ 1KHZ 8KHZ 20KHZ

(Binary System)

1100 -1.0~+1.0 -1.0~+1.0 -0.5~+0.5 +0.2~+1.5 +3.5~+5.5 -2.0~-0.5

DISCO 1101 +9.5~+11.5 +7.5~+9.5 +6.0~8.0 +0.2~+1.5 +3.5~+5.5 -2.0~-0.5
VOCAL 1110 -11.5~-9.5 -3.5~-1.5 -2.5~-0.5 +0.2~+1.5 +3.5~+5.5 -2.0~-0.5
ROCK&ROLL 1111 -0.5~+1.5 +5.0~+7.0 +4.5~+6.5 +0.2~+1.5 +3.5~+5.5 -2.0~-0.5