Yamaha MT-400 Service Manual

MULTITRACK CASSETTE RECORDER

SERVICE MANUAL

MIC/LINE INPUT

INSERT I/O

2

INSERT I/O

1

1

GAIN

GAIN

LINE MIC

LINE MIC

HIGH

HIGH

–12 +12

–12 +12

MID

MID

–12 +12

–12 +12

LOW

LOW

–12 +12

–12 +12

AUX

AUX

1

1

010

AUX
2

MIX CUE

MIC/LINE
to L

TAPE

PAN

10
9
8
7
6
5
4
3
2
1
0

010

AUX
2

010

010

MIX CUE MIX CUE MIX CUE

010

010

TAPE

MIC/LINE
to R

MIC/

TAPE

LINE

INPUT-FLIP

INPUT-FLIP

PAN

LR

LR

10
9
8
7
6
5
4
3
2
1
0

2

TAPE
MIC/

LINE

3

GAIN

LINE MIC

HIGH

–12 +12

MID

–12 +12

LOW

–12 +12

AUX
1

010

AUX
2

010

010

MIC/LINE
to L

TAPE

INPUT-FLIP

PAN

LR

10
9
8
7
6
5
4
3
2
1
0

3

TAPE
MIC/

LINE

4

GAIN

LINE MIC

HIGH

–12 +12

MID

–12 +12

LOW

–12 +12

AUX
1

010

AUX
2

010

010

MIC/LINE
to R

TAPE

INPUT-FLIP

PAN

LR

10
9
8
7
6
5
4
3
2
1
0

TAPE
MIC/

LINE

4

LEVEL

LEVEL

MIN MAX

STEREO INPUT

L 6R 8R7L

5

7

5L–6

R

LEVEL

010

010

MULTITRACK CASSETTE RECORDER

TAPE SPEED CONTROL

PITCH

–

SYNC

MONITOR/PHONES

STEREO
ST+CUE

CUE

STEREO

10

9
8
7
6
5
4
3
2
1
0

L–8R

ZERO STOP

ON

OFFONOFF

+6

+3

0

–5

–10

REC

1

OFF

4.8/ 9.5

+

NOISE REDUCTION SYSTEM

REC PLAY REW FF STOP PAUSE

AUX SEND

1

L

2

+6

POWER

+3

0

–5

–10

4

321

RL

3

2

OFF

OFF

L

R

METER SELECTREC SELECT

4TR4

STEREO

OFF

R

011437

PA

19981101-45000

CONTENTS

SPECIFICATIONS ................................................ 3/4

DIMENSIONS ........................................................... 4

PANEL LAYOUT .................................... 5

CIRCUIT BOARD LAYOUT ................. 8

BLOCK DIAGRAM

............................ 9

DISASSEMBLY PROCEDURE ............................ 10

IC BLOCK DIAGRAM .................................. 11

CIRCUIT BOARDS ...................................... 12

INSPECTIONS ....................................................... 15/17

TROUBLE SHOOTING ............... 19

CIRCUIT DIAGRAM ............................................... 21

PARTS LIST

HAMAMATSU, JAPAN

1.95K-998 Printed in Japan ’98.10

MT400

IMPORTANT NOTICE

This manual has been provided for the use of authorized Yamaha Retailers and their service personnel. It has been assumed
that basic service procedures inherent to the industry, and more specifically Yamaha Products, are already known and under­stood by the users, and have therefore not been restated.

WARNING : Failure to follow appropriate service and safety procedures when servicing this product may result in per-

IMPORTANT : This presentation or sale of this manual to any individual or firm does not constitute authorization certifi-

The data provided is belived to be accurate and applicable to the unit(s) indicated on the cover. The research engineering, and
service departments of Yamaha are continually striving to improve Yamaha products. Modifications are, therefore, inevitable
and changes in specification are subject to change without notice or obligation to retrofit. Should any discrepancy appear to
exist, please contact the distributor’s Service Division.

WARNING : Static discharges can destroy expensive components. Discharge any static electricity you body may have

IMPORTANT : Turn the unit OFF during disassembly and parts replacement. Recheck all work before you apply power

sonal injury, destruction of expensive components and failure of the product to perform as specified. For
these reasons, we advise all Yamaha product owners that all service required should be performed by an
authorized Yamaha Retailer or the appointed service representative.

cation, recognition of any applicable technical capabilities, or establish a principal-agent relationship of
any form.

accumulated by grounding yourself to the ground buss in the unit (heavy gauge black wires connect to
this buss.)

to the unit.

WARNING: CHEMICAL CONTENT NOTICE!

The solder used in the production of this product contains LEAD. In addition, other electrical/electronic and/or plastic (Where
applicable) components may also contain traces of chemicals found by the California Health and Welfare Agency (and possibly
other entities) to cause cancer and/or birth defects or other reproductive harm.

DO NOT PLACE SOLDER, ELECTRICAL/ELECTRONIC OR PLASTIC COMPONENTS IN YOUR MOUTH FOR ANY REASON WHAT
SO EVER!

Avoid prolonged, unprotected contact between solder and your skin! When soldering, do not inhale solder fumes or expose
eyes to solder/flux vapor!

If you come in contact with solder or components located inside the enclosure of this product, wash your hands before handling
food.

WARNING

Components having special characteristics are marked and must be replaced with parts having specification equal to those
originally installed.

2

SPECIFICATIONS

Tape Transport

MT400

Tape Type
Track Configuration
Tape Heads
Motor
Tape Speed
Pitch Control
Wow & Flutter
Rewind Time

Mixer

Frequency Response

S/N Ratio (at rated input &
output levels)

EQ

Recorder

Overall Frequency Response
Overall S/N Ratio
Overall Distortion
Erasure Rate
Noise Reduction

C46–90 cassette tapes (Type II)
4-track/4-channel, One-way Record-Play
4-track Record-Play, Hard Permalloy x 1, 4-track Erase, Ferrite x1
DC servo motor x1

4.8 cm/s, 9.5 cm/s
Approximately+/–10%

0.12% WRMS (9.5 cm/s)
Approximately 120 seconds for a C60 tape

20 Hz–20 kHz, +1/–4 dB, MIC IN—STEREO OUT

LINE IN—MONITOR OUT

65 dB/IHF-A, MIC IN—STEREO OUT (GAIN TRIM MAX)
70 dB/IHF-A, LINE IN—STEREO OUT (GAIN TRIM MIN)

LOW/Shelving Basic frequency: 80 Hz, Range: ±12 dB
MID/Peaking Basic frequency: 1 kHz, Range: ±12 dB
HIGH/Shelving Basic frequency: 12 kHz, Range: ±12 dB

50 Hz–14 kHz, +3/–5 dB (9.5 cm/s, NR OUT)
80 dB/IHF-A (NR IN) [at 3% distortion level]

2.0% (400 Hz, –10 dB)
55 dB (1 kHz, 0 dB, BPF)
dbx TYPE II

STEREO OUT L, R

AUX SEND

MONITOR OUT

SYNC OUT

PHONES (STEREO)

Output Impedance: 1 k ohm
Rated Load Impedance: 10 k ohm or higher
Rated Output Level: –10 dB (10 k ohm load)
Output Impedance: 1 k ohm
Rated Load Impedance: 10 k ohm or higher
Rated Output Level: –10 dB (10 k ohm load)

Output Impedance: 1 k ohm
Rated Load Impedance: 10 k ohm or higher
Rated Output Level: –10 dB (10 k ohm load)

Output Impedance: 1 k ohm
Rated Load Impedance: 10 k ohm or higher
Rated Output Level: –10 dB (10 k ohm load)

Rated Load Impedance: 8 to 40ohm
Rated Output Level: 30 mW+30 mW (40ohm load)

Control Jack

PUNCH I/O Foot switch: FC5 (optional)

General

Power Requirement
Dimensions (WxHxD)
Weight
Option for UK model

0 dB=0.775 Vrms.

DC 12V (650 mA or higher)
388 x 102 x 354 mm

2.8 kg
AC adapter KPA4N, KPA6N

Connections

# of I/Os

I/O Specifications

MIC/LINE

INSERT IN CH 1, 2

STEREO IN

INSERT OUT CH 1, 2

MIC/LINE x4
INSERT I/O x2
STEREO IN x2
AUX SEND x2
STEREO OUT L, R x1
MONITOR OUT L, R x1
SYNC OUT x1
PHONES L, R x1

Input Impedance: 10 k ohm
Rated Input Level: –10 to –50 dB (CH fader at rated levels)
Minimum Input Level: –56 dB (Gain trim max. CH fader max)

Input Impedance: 10 k ohm
Rated Input Level: –10 dB (CH fader at rated levels)
Minimum Input Level: –16 dB (CH fader max)

Input Impedance: 10 k ohm
Rated Input Level: –10 dB (CH fader at rated levels)
Minimum Input Level: –16 dB (Volume max)
Output Impedance: 100ohm
Rated Load Impedance: 10 kΩ or higher
Rated Output Level: –10 dB (10 kΩ load)

3

MT400

H:102

D:354

W:388

DIMENSIONS

Unit : mm

4

PANEL LAYOUT

Input channels

MT400

1

2

3

4
5
6

7

GAIN

LINE MIC

HIGH

–12 +12

MID

–12 +12

LOW

–12 +12

AUX
1

010

AUX
2

010

MIX CUE

010

MIC/LINE
to L

TAPE

PAN

10

9
8
7
6
5
4
3
2
1
0

TAPE
MIC/

LINE

INPUT-FLIP

LR

1

GAIN control

1

EQ control

2

AUX controls

3

CUE control

4

INPUT-FLIP switch

5

PAN control

6

Fader

7

Stereo Input

LEVEL controls

8

5L–6R

LEVEL

8

010

7L–8R

LEVEL

010

Monitor / Master Section

MONITOR/PHONES

LEVEL

9

MIN MAX

STEREO
ST+CUE

CUE

10

STEREO

10

9
8
7
6
5
4
3
2
1
0

11

MONITOR LEVEL control

9

MONITOR select switch

10

STEREO fader

11

5

MT400

Recorder Section

TAPE SPEED CONTROL

PITCH

–

ON

OFF

SYNC

16 17

12 13

4.8/ 9.5

+

ZERO STOP

ON

OFF

NOISE REDUCTION SYSTEM

14

3

2

1

OFF

OFF

R

L

OFF

OFF

R

L

METER SELECTREC SELECT

4TR4

STEREO

15

18

PITCH control

12

Tape speed switch

13

REC SELECT switches

14

METER SELECT switch

15

dbx switch

16

ZERO STOP switch

17

Tape counter

18

Counter reset button

19

Cassette compartment

20

19

20

Transport Section

REC PLAY REW FF STOP PAUSE

21 22 23 24 25 26

REC

button ( )

21

PLAY button ( )

22

REW button ( )

23

FF button ( )

24

STOP button ( )

25

PAUSE button ( )

26

6

Meter Section

+6

+3

27

0

–5

–10

REC

28

Input / Output Section

MT400

Level meters

27

REC SELECT indicator

+6

POWER

+3

0

–5

–10

4

321

RL

29

28

POWER indicator

29

31 32

MIC/LINE INPUT

INSERT I/O

INSERT I/O

1

MIC/LINE INPUTs 1-4

30

INSERT I/O

31

STEREO INPUTs

32

AUX SEND

33

Front Panel

2

34 35

PHONES PUNCH I/O

Rear Panel

DC 12VPOWER

ON/ OFF

30

33

3

4

PHONES

34

PUNCH I/O

35

5

L6R

STEREO INPUT

8

R

7

L

SYNC OUT MONITOR OUT STEREO OUT

AUX SEND

1

2

RLRL

36 37 38

POWER ON/OFF switch

36

DC 12V

37

SYNC OUT

38

MONITOR OUTs

39

STEREO OUTs

40

39 40

7

MT400

CIRCUIT BOARD LAYOUT

MIX 1/3

SUB 1/3

MIX 2/3

SUB 2/3

REC 1/2

MIX 3/3

SUB

3/3

REC 2/2

8

BLOCK DIAGRAM

IC101

31

IC103

27

IC104

31

21 67

IC106

MT400

IC201

31

IC303

27

IC105

31

21 67

21 67

21 67

21

IC107

IC108

IC109

IC110

IC110

67

31

IC111

67

MT400-3000 0

9

MT400

DISASSEMBLY PROCEDURE

1. Lower Case

1-1 Remove the seven (7) screws marked [320]. The

lower case can then be removed. (Fig.1)

[320]

〈

REAR

4. SUB 2/3, 3/3 Circuit Boards

4-1 Remove the lower case. (See Procedure 1.)
4-2 Remove the three (3) screws marked [320d] and

the two (2) screws marked [320e].
The SUB2/3 circuit board can then be removed.

〉

(Fig.2, Fig.3)

4-3 Remove the four (4) screws marked [320f]. The SUB

3/3 circuit board can then be removed. (Fig.2)

[320f] [320b] [320a] [320c]

SUB

3/3

[320f]

[320b]

[320c]

[320a]

2. Cassette Mechanism

2-1 Remove the lower case. (See Procedure 1.)
2-2 Remove the five (5) screws marked [320a]. The

cassette mechanism can then be removed. (Fig. 2)

3. REC 1/2, 2/2 Circuit Boards

3-1 Remove the lower case. (See Procedure 1.)
3-2 Remove the cassette mechanism. (See Procedure 2.)
3-3 Remove the six (6) screws marked [320b]. The REC

1/2 circuit board can then be removed. (Fig.2)

3-4 Remove the two (2) screws marked [320c]. The REC

2/2 circuit board can then be removed. (Fig.2)

〈

[320]

[320]: Bind Head Tapping Screw-P 3X10 MFZN2BL (EP630660)

Fig.1

FRONT

〉

〈

REAR

〉 〈

[320b]

REC 1/2

Fig.2

〈

Bottom

[320b]

〉

[320d]

SUB

2/3

[320b]

[320e]

FRONT

〉

10

〈

Top

Fig.3

〉

11A

2

3

4

5

6

7

1Y

2A

2Y

3A

3Y

V

SS

8

9

10

11

12

13

14

V

DD

6A

6Y

5A

5Y

4A

4Y

TC4069UBP(IG001720)

Hex Inverter

1Input (Output)1

2

3

4

5

6

7

Output (Input)1

Output (Input)2

Input (Output)2

Control2

Control3

V

SS

8

9

10

11

12

13

14

V

DD

Control1

Control4

Input (Output)4

Output (Input)4

Output (Input)3

Input (Output)3

TC4066BP(IX631591)

Quad Bilateral Swich

BA7755A(XH519A00)

Head Switcher

BA6137(XA534A00)

LED Driver

AN6292NK(XJ637A00)

Dual dbx NR

NJM2068LD(XM356A00)
NJM4558L(IX614610)
M5216L(XB419A00)
M5218AL(XH471A00

)

Dual Operational Amplifier

1A2 3 4 5 6 7 8

IN V

+IN

OUT

AAA

+VIN

+IN

OUT

BBB

+

B

+

1 2 3 4 5

VCC SW GND CTRL1CTRL2

D1

+ + + + +

+

Constant

Current

Circuit

1D22D33D44

GND5D56Amp

Output

7IN8

V

CC

9

3

8

9

20

21

26

ENPHASIS

BAND PASS FILTER IN

REC OUT

1

28

GND

+

2

27

R/P IN R/P IN

ENPHASIS

4

LINE OUT LINE OUT

5

24

ENPHASIS ENPHASIS

6

23

CCA-A OUT CCA-A OUT

7

22

CCA-B IN CCA-B IN

BAND PASS FILTER IN

REC OUT

10

19

BAND PASS FILTER OUT BAND PASS FILTER OUT

11

13

1618

LEVEL SENSOR IN

TIMING CURRENT ADJ.

LEVEL SENSOR IN

12

17

TIMING CAP. TIMING CAP.

DECODE / ENCODE SW

14

15

SW

B CH.

A CH.

+

DE

OFF

LINE AMP.

OFF

EN ENDE

+

+

+

DE

OFF

BUFFER

EN

EN
OFF OFF

DE DEEN

+

EN

CCA-B

CCA-A

REC OUT
AMP.

OFF

LEVEL SENSOR

OFF

DE DEEN

+

+

EN PHASIS

AMP.

25

5. SUB 1/3 Circuit Board

5-1 Remove the lower case. (See Procedure 1.)
5-2 Remove the PITCH knob of the TAPE SPEED

CONTROL on the upper case and the six (6) screws
marked [320g].
The SUB 1/3 circuit board can then be removed.
(Fig.4)

6. MIX 1/3 Circuit Board

6-1 Remove the lower case. (See Procedure 1.)
6-2 Remove the SUB 1/3 circuit board. (See Procedure 5.)
6-3 Remove the knob on the upper case and the twelve

(12) screws marked [320h].
The MIX 1/3 circuit board can then be removed.
(Fig.4)

7. MIX 2/3, 3/3 Circuit Boards

7-1 Remove the lower case. (See Procedure 1.)
7-2 Remove the four (4) screws marked [320I] on the

plate. The plate with the MIX 2/3 and 3/3circuit
boards can then be removed. (Fig.4)

7-3 Remove the holding plate of each jack. The each

circuit board can then be removed.

MT400

IC BLOCK DIAGRAM

〈

FRONT

[320h]

〉

[320g]

[320i]

SUB 1/3

[320g]

MIX 1/3

MIX 3/3

〈

REAR

[320h]

〉

MIX 2/3

11

Fig.4

[320h]

[320i]

MT400

CIRCUIT BOARDS

MIX-1/3 Circuit Board

to MIX 2/3-CN108

to SUB 1/3-CN101

to MIX 2/3-CN112

to SUB 2/3-CN107

to MIX 2/3-CN109

to MIX 3/3-CN110

to SUB 1/3­CN102

12

to REC 1/2-CN504

Component side

MIX : MT400-3400

to REC 1/2-CN506

DC IN POWER SW.

to REC 1/2-CN501

to REC 1/2

-CN502

from MIX 1/3

-CN106

from MIX 1/3-CN107

MT400

MIX-2/3 Circuit Board

1-INSERT I/O

1 2 3 4 5L 6R 7L 8R

from MIX 1/3-CN101

MIX-3/3 Circuit Board

AUX SEND

12

MIC / LINE INPUT

2-INSERT I/O

STEREO INPUT

from MIX 1/3-CN111 to MIX 1/3-CN109

Component side

SUB-1/3 Circuit Board

from MIX 1/3-CN103

MIX : MT400-3400

SUB : MT400-3600

Component side

SUB-2/3 Circuit Board

STEREO OUT

LR

MONITOR OUT

LR

SYNC

OUT

from MIX 1/3-CN104

from REC 1/2-CN507

Component side

SUB-3/3 Circuit Board

Component side

Component side

13

MT400

REC-1/2 Circuit Board

from SUB 3/3-CN109from SUB 1/3-CN103to SUB 2/3-CN108

from SUB 1/3-CN104

REC-2/2 Circuit Board

PUNCH I/O PHONES

from MIX 1/3-CN105

from REC 1/2-CN503

Component side

to REC 2/2-CN508

Component side

REC : MT400-3500

14