Denon DRR-M31 Service Manual

For Europe model

SERVICE MANUAL

MODEL

STEREO CASSETTE DECK

DRR-M31

Some illustrations using in this service manual are slightly different from the actual set.

16-11, YUSHIMA 3-CHOME, BUNKYOU-KU, TOKYO 113-0034 JAPAN

Telephone: [phone]

X0166V.02 DE/CDM 0302

SAFETY PRECAUTIONS

The following check should be performed for the continued protection of the customer and service technician.

LEAKAGE CURRENT CHECK

Before returning the unit to the customer, make sure you make either (1) a leakage current check or (2) a line to chassis
resistance check. If the leakage current exceeds 0.5 milliamps, or if the resistance from chassis to either side of the
power cord is less than 460 kohms, the unit is defective.

2DRR-M31

2

DISASSEMBLY

(Follow the procedure below in reverse order when reassembling)

1. TOP COVER

(1) Remove 2 screws ① fixing from the both

sides.

(2) Remove 5 screws ② fixing to the Rear Plate,

then detach the Top Cover in the arrow di­rection .

2. FRONT PANEL

(1) Disconnect 1 HCU joiner coming from the

front P.W.B.

(2) Remove 4 screws ③ fixing the Front Panel at

the bottom.

(3) Whil releasing 2 hooks, detach the Front

Panel.

3DRR-M31

3. CASSETTE MECHA. ASS’Y

(1) Remove 4 screws ④ fixing the Cassette

Mecha. Ass’y.

(2) Disconnect 3 connectors, then detach the

Cassette Mecha. Ass’y.

3

4. REAR PLATE

(1) Pull up the Power Cord together with the cord

bush to disengage from the Rear Plate.

(2) Remove 3 screws ⑤ fixing the 4P pin jack and

AC outlet respectively.

(3) Remove 1 screw ⑥ , and detach the Rear Plate.

5. MAIN P.W.B.

(1) Remove 1 screw ⑦ fixing the AMP P.W.B.
(2) Pull up the AMP P.W.B. as shown in the arrow

direction, and disconnect 2 connectors.

(3) Remove 4 screws ⑧ fixing the Main P.W.B.
(4) Release 3 pieces of P.W.B. spacers.
(5) Disconnect the connector from the Trans Unit.
(6) Take off the Main P.W.B.

4DRR-M31

Connector

6. DISPLAY P.W.B.

(1) Pull out the knob (E).
(2) Remove the nut and washer ⑨ for the rotary

switch.

(3) Remove 9 screws ⑩ .
(4) Take off the Display P.W.B.

AMP

4

ADJUSTMENTS

6

ADJUSTMENTS

Adjusting and Checking the Mechanism Section

5DRR-M31

1. Replacement of the pinch roller

Before replacing the pinch roller, clean the tape contact
surface of the pinch roller and the tape contact surface of
the capstan shaft. After replacement, run a C-90 tape
without a pad and check for the presence of tape curl at
the tape guide portion of the head.

2. Checking the pinch roller pressure

Set to the playback condition and hook a bar-type spring
scale to the bracket above the center line of the pinch
roller. Pull the pinch roller away from the capstan shaft,
then allow the pinch roller to come into contact with the
capstan shaft and check that the reading of the bar-type
spring scale is between 2.45 N~3.92 N (250~400 g) when
the pinch roller starts to rotate or pull force indicates more
than 7.85 mN (80 g).
Replace the pinch roller when the value falls outside of
the specified range.

Capstan shaft

Pinch roller

4. Adjustment of the recording/playback head

Azimuth adjustment
Load side A of the A-BEX TCC-153 test tape facing
forward, and adjust.
(1) Play in the FWD direction and turn the azimuth

adjustment nut for the FWD side so that the

Lissajous’s figure becomes maximum at (A) and
minimum at (B).
(2) Play in the REV direction and turn the azimuth

adjustment nut for the REV side as adjusting the

FWD side method.
(3) Adjust (1) and (2) again.
(4) Apply screw lock to the adjustment locations.

PB Amp

LINE OUT

L

V

R

H

2.45 3.92N
(250

400g)

3. Replacement of the recording/playback
assembly

3-1 Removal of the head assembly
(1) Remove the 2 BRACKET-HEAD fastening screws.
(2) Remove one screw fixing P.W.B.
3-2 Mounting the recording/playback head assembly

Perform by following the steps of Section 3-1
Removal of the head assembly in reverse.

head

A-BEX TCC-153

REC/PB HEAD

A

FWD SIDE

B

REV SIDE

5. Checking the winding torque

Load a cassette type torque meter (Sony TW2111A at
the FWD side) and check that the reading of the torque
meter during playback is
294 to 686 mN-cm (30 to 70 g-cm) at the center value.

5

6. Checking the back tension torque at the time

r

of recording and playback

Load a cassette type torque meter (Sony TW2111A at
the FWD side, Sony TW2121A at the REV side) and check
that the reading of the torque meter during playback is

9.8~58.5 mN-cm (1~6 g-cm) and that there is no
unevenness.

7. Checking the FF and REW torque

Load a cassette type torque meter (Sony TW2231) and
check that the value indicated by the torque meter for
winding and rewinding is between 686 mN-cm~
(70~150 g-cm).

1.47 N-cm

Adjusting and Checking the Electrical Section

6DRR-M31

8. Checking the FF and REW time

Load a Type 1 tape (UD-1), and check that the time for
FF and REW is less than 120 seconds. When outside of
the specified range, check Steps 5 and 6.

9. Checking the erroneous erasure prevention,
and the metal and chrome switch operations

Check that detection lever is operating the switch properly
depending upon the presence or absence of a hole.

Measuring instruments needed for the adjustments

(1) Low frequency oscillator
(2) Variable resistance attenuator
(3) Electronic voltmeter
(4) Oscilloscope
(5) Frequency counter
(6) Adjustment screwdriver
(7) Test tapes

MTT-111, MTT-114N, MTT-150, Type1 tape (UD-1)

(8) Mirror cassette for the transport (A-BEX TCC-902)

Adjustment precaution

(1) Before adjustments, use gauze or a swab moistened

with alcohol to wipe the surface of the heads, the
capstan shaft, and the pinch roller.

(2) Demagnetize the record/playback head and the

erase head with a head eraser.

(3) Completely demagnetize the driver to be used for

the adjustments.

(4) Unless otherwise specified, set the various operation

controls as indicated below.
Dolby NR switch: Off

1. Tape transport check

Load the mirror cassette for the transport, and illuminate
the area around the fixed guide of the record/playback
head with a lamp and observe.
Check that the tape edge is not hitting the tape guide
portion.
Note that the tape transport is the greatest factor affecting
the performance of the cassette deck. Never move the
inspection locations without good reason.
For information about replacement and adjustment of the
record/playback head, see the section “Adjustment and
checking of the mechanism”.

2. Tape speed check and adjustment

(1) Connect the frequency counter to the LINE OUT pin

and load the test tape (MTT-111).

(2) Playback FWD side of the test tape. At about halfway

through the tape, where the tape transport is stable,
confirm that the frequency counter will have a
reading within the range of 3,000 Hz ±10 Hz.

(3) Check REV side also that the counter reading

indicates within 2955~3045Hz.
Note: Adjust within 30 seconds, after pre-heating
(Play) of 20min, or more.

Frequency counte

PB Amp

LINE OUT

MTT-111

3000

3000Hz
10Hz

6

3. Azimuth Adjustment

)

(1) Connect an electronic voltmeter to the Line Out

terminal, and set Test tape MTT-114N into the Unit.

(2) Playback FWD side,and adjust the azimuth screw A

so as to get maximum indication on the voltmeter,
then make the same adjustment with the screw B for
REV side.

(3) Readjust if the output level difference exceeds 2dB

after adjustment, and also confirm that the phase
difference in the both channels is within ±45
Note: In order to prevent the backlash of the azimuth
screw, end in the clockwise rotation.

7DRR-M31

PB Amp

LINE OUT

.

MTT-114N

V. V

4. PB Output Level Adjustment

(1) Connect an electronic voltmeter to the Line Out

terminal, and set Test tape MTT-150 into the Unit.

(2) Playback FWD side, and adjust the VR301 (Lch) and

VR302 (Rch) so that the voltmeter indicates 400mV
±0.5dB.

5. REC Level Adjustment

(1) Set Test Tape (Type1 tape: UD-1) into the Unit,and

record 400mV −10dB 400Hz signal at JK301 input
level on the tape.

(2) Playback the recorded signal, and adjust VR304 (Lch)

and VR303 (Rch) so that the voltmeter indicates

−10dB ±0.5dB at JK301 output level.

MTT-150

400Hz

A

FWD SIDE

ATT

V. V

B

REV SIDE

PB Amp

LINE OUT

V. V

REC Amp

LINE IN

LINE OUT

PB Amp

Type 1 tape(UD-1

7

6. Bias Current Adjustment

)

(1) Set Test Tape (Type1 tape: UD-1) into the Unit, and
record 400mV -23dB 1.25kHz/12.5kHz signal at JK301
level on the tape.
(2) Playback the recorded signal, and adjust VR306 (Lch)

and VR305 (Rch) so that the level difference between
both frequencies becomes within the range of
+2dB ~ -0.5dB on the voltmeter.

ADJUSTMENT POINTS

ATT

1.25kHz

12.5kHz

V. V

LINE IN LINE OUT

JK301

8DRR-M31

REC Amp

LINE IN

LINE OUT

PB Amp

Type 1 tape(UD-1

(Deck Mecha.)

MAIN P.W.B

Azimuth Adjust

R/P Level Adjust

PB GAIN Adjust

Tape Speed Adjust

Rch
VR304

Lch
VR303

Lch
VR301

Rch
VR302

Lch
VR306

Rch
VR305

AMP P.W.B

8

BLOCK DIAGRAM

DRR-M31

9

CLOSE

OPEN

LOADING
MOTOR

CAPSTAN
MOTOR

SOL

R/P HEAD

E. HEAD

HALL IC

M

M

CrO2 SW

NOR SW

F. REC

R. REC

HALF

MODE

TU201,202

BIAS ADJ.

VR201,202

μCOM. CLOSE
μCOM. OPEN

+5V

IC302
MOTOR
DRIVE

+5V

μCOM

R/P
SWITCHING

-7V

L203

TR204
TR205

BIAS OSC

μCOM

TR506
TR507

μCOM. REEL PULSE

μCOM

R/P

+B

-7V

+7V

TR203

PLAYBACK
AMP

IC201

BIAS TRAP

+5V

μCOM

R. MUTE

TR501

NOR

CrO

2

TR307
TR308

SOLENOID
μCOM

PLAY BACK LEVEL ADJ.

VR203,204

TR206,207

NOR

REC AMP REC LEVEL ADJ.

IC301

TR303

TR304

TR502

TR504 TR505

MOTOR
μCOM

+12V

RESET

VR301
VR302

IC501

μCOM

TR208,209

μCOM
R/P

TR510

TR305,306

NOR

+5V

P. OFF

PB IN

REC OUT

TR301,302

IC203

DOLBY IC

TR201

-7V

KEY
& LED

DISTLAY PWB

PB OUT ( Lch )

REC IN

D.RP
TR509 ( μCOM )

TR312

2

CrO

R/P PWB

TR313

-7V

TR328

MPX
FILTER

L201,202

TR314

+7V

TR327

TR315

+5V

TR326

TR324

IC205

TR316

μCOM
BIAS

IC304

TR325

IC204
LEVEL DETECT AMP ( A/D )

AUTO LEVEL CONTROL

P. OFF

+12V

DOLBY IC
PB OUT ( Rch )

MAIN PWB

μCOM. SO

μCOM. SI

μCOM. SCK

μCOM

A/D INPUT

TR211

μCOM
R. MUTE

TR323

TP215,216

TR317
( LINE MUTE OUT )

+7V

TR212

P. ON

LD405

(

Green

T101
POWER TRANS

LINE OUT

LINE MUTE

LINE IN

TR213,214

CD SYNCHRO

JK301

AC PLUG

(

9

SEMICONDUCTORS





IC's



µ µ

µPD78044FGF (IC203)

µ µ

P113 / FIP21

P112 / FIP20

P111 / FIP19

P110 / FIP18

P107 / FIP17

P106 / FIP16

VLOAD

P105 / FIP15

P104 / FIP14

P103 / FIP13

P102 / FIP12

P101 / FIP11

P100 / FIP10

P97 / FIP9

P96 / FIP8

P95 / FIP7

10DRR-M31

P114 / FIP22

P115 / FIP23

P116 / FIP24

P117 / FIP25

P120 / FIP26

P121 / FIP27

P122 / FIP28

P123 / FIP29

P124 / FIP30

P125 / FIP31

P126 / FIP32

P127 / FIP33

VDD

P70

P71

P72

IC (VPP)

P00 / INTP0

P01 / INTP1

P02 / INTP2

P03 / INTP3

P30 / TO0

P31 / TO1

P32 / TO2

6061

62

64

63

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

57

59

58

55

56

54

53

5152

TOP VIEW

46

4748

49

50

41

42

P33 / TI1

40

39

P34 / TI2

P35 / PCL

38

P36 / BUZ

37

36

P37

X2

35

X1

34

VSS

33

32

XT2

31

P04 / XT1

30

AVREF

29

AVDD

28

P10 / ANI0

27

P11 / ANI1

26

P12 / ANI2

25

P13 / ANI3

43

45

44

3

2

P94 / FIP6

P93 / FIP5

P92 / FIP4

4567

P91 / FIP3

P90 / FIP2

P81 / FIP1

P80 / FIP0

1

11

9

8

10

VDD

P26 / SO0

P27 / SCK0

P25 / SI0

12 13

P24 / BUSY

14

P23 / STB

P22 / SCK1

15 16

P21 / SO1

17 18 19 20

P74

RESET

P20 / SI1

P73

21

AVSS

22

23 24

P17 / ANI7

P16 / ANI6

P15 / ANI5

P14 / ANI4

PPPPPD78044FGF Terminal Function

Pin

No.

10 P26/SO0
11 P26/SI0 REC  REV I Hi-z Deck mecha REC REV SW input
12 P24/BUSY PACK I Hi-z Deck mecha PACK SW input
13 P23/STB
14 P22/SCK1 SERCLK I Hi-z DENON BUS communication clock signal (Edge intervention)
15 P21/SO1 SEROUT O Hi-z DENON BUS communication output data signal
16 P20/SI1 SER  IN I Hi-z DENON BUS communication input data signal
17 RESET RESET I Hi-z Reset input
18 P74 R  MUTE
19 P73 HEADSW O Hi-z Head switching control signal (L: PB only)
20 AVSS AVSS O
21 P17/AN17 RVSMOD I Hi-z Reverse mode input signal
22 P16/AN16 KEYIN  2 I Hi-z Tact operating button input No.2
23 P15/AN15 KEYIN  1 I Hi-z Tact operating button input No.1
24 P14/AN14 KEYIN  1 I Hi-z Tact operating button input No.0
25 AN13 MSREF I Hi-z Music serch detection reference voltage

Port Name Symbol I/O Ini Function

1 P94/FIP6 MTCONT2 O Hi-z Reel, Loader motor control
2 P93/FIP5 MTCONT1 O Hi-z Reel, Loader motor control
3 P92/FIP4 LED  FP O Hi-z LED output FWD, PLAY ind. (H: light )
4 P91/FIP3 LED  RP O Hi-z LED output REV, PLAY ind. (H: light )
5 P90/FIP2 LED  REC O Hi-z LED output REC ind. (H: light )
6 P81/FIP1 LED  SRS O Hi-z LED output CD SRS ind. (H: light )
7 P80/FIP0 LED  PWR O Hi-z LED output POWER. (H: light )
8VDD VDD



+5V Power

9 P27/SCK0 REC  FWD I Hi-z Deck mecha REC FWD SW input





I Hi-z Not used (connect to GND)

I Hi-z Not used (connect to GND)

Hi-z REC mute control signal (H: mute)



Analog GND



10