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– 5 –

.......................................................... 6

........................................................................ 11

3-1. Front Panel ......................................................................... 35
3-2. Slider (Cam) ........................................................................ 35
3-3. Base Unit (MBU-5B) and BD Board .................................. 36
3-4. SW Board and Loading Motor (M103) .............................. 36

..................................................................... 37

............................... 41

6-1. Circuit Boards Location ...................................................... 50
6-2. Block Diagrams

• BD Section ....................................................................... 51
• Input/Output Section ........................................................ 53
• Control Section ................................................................ 55
• Power Section .................................................................. 58

6-3. Printed Wiring Board – BD Section – ................................. 61
6-4. Schematic Diagram – BD (1/2) Section – ........................... 63
6-5. Schematic Diagram – BD (2/2) Section – ........................... 65
6-6. Schematic Diagram – Jack (1/2) Section – ......................... 67
6-7. Schematic Diagram – Jack (2/2) Section – ......................... 69
6-8. Printed Wiring Board – Jack Section – ............................... 71
6-9. Printed Wiring Board – Main Section – .............................. 73
6-10. Schematic Diagram – Main (1/5) Section – ...................... 77
6-11. Schematic Diagram – Main (2/5) Section – ...................... 79
6-12. Schematic Diagram – Main (3/5) Section – ...................... 81
6-13. Schematic Diagram – Main (4/5) Section – ...................... 83
6-14. Schematic Diagram – Main (5/5) Section – ...................... 85
6-15. Schematic Diagram – BD Switch Section – ..................... 87
6-16. Printed Wiring Board – BD Switch Section – ................... 87
6-17. Printed Wiring Board – Panel Section – ............................ 89
6-18. Schematic Diagram – Panel Section – .............................. 91
6-19. Printed Wiring Board – Power Section – .......................... 93
6-20. Schematic Diagram – Power Section – ............................. 95
6-21. Printed Wiring Board – Trans Section – ........................... 97
6-22. Schematic Diagram – Trans Section – .............................. 99
6-23. IC Block Diagrams ......................................................... 101
6-24. IC Pin Functions ............................................................. 105

7-1. Case Section ...................................................................... 115
7-2. Front Panel Section ........................................................... 116
7-3. Chassis Section ................................................................. 117
7-4. Mechanism Deck Section (MDM-5B) .............................. 118
7-5. Base Unit Section (MBU-5B) ........................................... 119

...................................... 120

– 6 –

The special jig (J-2501-149-A) is useful for checking the waveform of the BD board. The names of terminals and the checking items to be
performed are shown as follows.

GND : Ground
I+3V : For measuring IOP (Check the deterioration of the optical pick-up laser)
IOP : For measuring IOP (Check the deterioration of the optical pick-up laser)
TEO : TRK error signal (Traverse adjustment)
VC

: Reference level for checking the signal

RF

: RF signal (Check jitter)

RF
VC
TEO

For
MDM-3

For
MDM-5

IOP
I-3V

VC
RF
TEO
IOP
I+3V
GND

VC

RF

TEO

IOP

I+3V

GND

1

5

1

6

CN110

RF

5P Connector

6P connector

VC

TEO

IOP

I+3V

GND

Mechanism deck

– 7 –

The IOP value labeled on the pick-up can be recorded in the non-volatile memory. By recording the value, it will eliminate the need to look
at the value on the label of the optical pick-up. When replacing the pick-up or non-volatile memory (IC171 of BD board), record the IOP
value on the pick-up according to the following procedure.

For buttons or knobs not specified as (Deck A) or (Deck B) in the procedure, use that of the corresponding deck.

Record Precedure:
1. With the power ON, press the  0 (Deck B)  button while pressing the  OUTPUT  and  CLEAR (Deck A)  buttons together.
2. Rotate the  AMS  knob to display “(Service)”, and press the  YES  button.
3. Rotate the  AMS  knob to display “lop.Write” (S: 28), and press the  YES  button.
4. The display becomes “Ref=@@@.@” (@ is an arbitrary number) and the numbers which can be changed will blink.
5. Input the IOP value written on the optical pick-up.

To select the number : Rotate the  AMS  knob.
To select the digit

: Press the  AMS  knob.

6. When the  YES  button is pressed, the display becomes “Measu=@@@.@” (@ is an arbitrary number).
7. As the adjustment results are recorded for the 6 value. Leave it as it is and press the  YES  button.
8. The value will be recorded in the non-volatile memory and the display will become “Iop Write”.
9. Press the  MD SYNC  button to complete.

Display Precedure:
1. With the power ON, press the  0 (Deck B)  button while pressing the  OUTPUT  and  CLEAR (Deck A)  buttons together.
2. Rotate the  AMS  knob to display “(Service)”, and press the  YES  button.
3. Rotate the  AMS  knob to display “lop.Read” (S: 27).
4. “@@.@/##.#” is displayed and the recorded contents are displayed.

@@.@ : indicates the Iop value labeled on the pick-up.
##.#

: indicates the Iop value after adjustment

5. To end, press the  AMS  button or  MENU/NO  button to display “Iop Read”. Then press the  MD SYNC  button.

– 8 –

• 0.9 mW power

Specified value : 0.84 to 0.92 mW

• 7.0 mW power

Specified value : 6.8 to 7.2 mW
lop (at 7mW)

• Labeled on the optical pickup

Iop value ± 10mA

• Traverse waveform

Specified value : Below 10% offset

• Error rate check

Specified value : For points a, b, and c
C1 error : Below 220
AD error : Below 2

• Error rate check

Specified value:
a.When using test disc (MDW-74/AU-1)

C1 error : Below 80
AD error : Below 2

b.When using check disc (TDYS-1)

C1 error : Below 50

• CPLAY error rate check

Specified value:
C1 error : Below 80
AD error : Below 2

• Unsatisfactory if displayed as T=@@ (##) (NG”

NG
(@@, ## are both arbitrary numbers)

Before performing repairs, perform the following checks to determine the faulty locations up to a certain extent.
Details of the procedures are described in “5 Electrical Adjustments”.

Laser power check
(5-6-2 : See page 44)

Traverse check
(5-6-3 : See page 44)
Focus bias check
(5-6-4 : See page 45)

C PLAY check
(5-6-5 : See page 45)

Self-recording/playback
check
(REC/PLAY)
(5-6-6 : See page 45)

TEMP check
(Temperature
compensation
offset check)
(5-6-1 : See page 44)

Criteria for Determination
(Unsatisfactory if specified value is not satisfied)

• Clean the optical pick-up
• Adjust again
• Replace the optical pick-up

• Replace the optical pick-up

• Replace the optical pick-up

• Replace the optical pick-up

• Replace the optical pick-up

If always unsatisfactory:
• Replace the overwrite head
• Check for disconnection of the circuits around the

overwrite head

If occasionally unsatisfactory:
• Check if the overwrite head is distorted
• Check the mechanism around the sled
• Check for disconnection of the circuits around D101

(BD board)

• Check the signals around IC101, IC121, CN102,

CN103 (BD board)

Measure if unsatisfactory:

The criteria for determination above is intended merely to determine if satisfactory or not, and does not serve as the specified value for
adjustments.
When performing adjustments, use the specified values for adjustments.

The system microprocessor can be reset in the following procedure.
Use these procedure when the unit cannot be operated normally due to the overrunning of the microprocessor, etc.
Procedure :
Disconnect the power plug from the outlet, short-circuit Pins 

1 and 2 of CN302 of the MAIN board and discharge the backup battery.

The fluorescent display tube can be lit completely by the following method:
With the power ON, press the  TIMER  button while pressing the  p (Deck A)  and  MENU/NO (Deck A)  buttons.
To turn off, press the  DISPLAY  button.

3 2 1

CN302