MDS-JB940 - Sony Audio Service Manual (repair manual)

US Model

Canadian Model

AEP Model

UK Model

Model Name Using Similar Mechanism

NEW

MD Mechanism Type

MDM-7A

Optical Pick-up Name

KMS-260B/J1N

U.S and foreign patents licensed from Dolby
Laboratories Licensing Corporation.

Inputs

Outputs

MiniDisc digital audio system

MiniDisc

Semiconductor laser (

λ = 780 nm) 

Emission duration:  continuous

MAX 44.6 

µW

1)

Material: GaAlAs

400 rpm to 900 rpm 

ACIRC (Advanced Cross Interleave 
Reed Solomon Code)

44.1 kHz

ATRAC (Adaptive TRansform 
Acoustic Coding)/ATRAC 3

EFM (Eight-to-Fourteen 
Modulation)

2 stereo channels

5 to 20,000 Hz 

±0.3 dB

Over 100 dB during play

Below measurable limit

Jack type:  phono
Impedance:  47 kilohms
Rated input:  500 mVrms 
Minimum input:  125 mVrms

Connector type:  square optical
Impedance:  660 nm (optical wave 
length)

Connector type:  square optical
Impedance:  660 nm (optical wave 
length)

Jack type:  phono
Impedance:  75 ohms
Rated input:  0.5 Vp-p, 

±20 %

Jack type:  stereo phone
Rated output:  28 mW
Load impedance:  32 ohms

Jack type:  phono
Rated output:  2 Vrms (at 50 
kilohms)
Load impedance:  over 10 kilohms

Connector type:  square optical
Rated output:  –18 dBm
Load impedance:  660 nm (optical 
wave length)

Jack type:  phono
Rated output:  0.5 Vp-p (at 75 ohms)
Load impedance:  75 ohms

General

Supplied accessories

US and foreign patents licensed from Dolby Laboratories.

Design and specifications are subject to change without 
notice.

U.S.A. and Canada

120 V AC, 60 Hz

Europe

230 V AC, 50/60 Hz

18 W

430 

× 111 × 286 mm (17 × 4

3

/

8

 

× 

11

3

/

8

 in.) (w/h/d) incl. projecting 

parts and controls

5.3 kg (11 lbs 11 oz)

This MD deck comes with the following items:

Audio connecting cords (2)

Optical cable (1)

Remote commander (remote) (1)

R6 (size-AA) batteries (2)

 

2010L05-1
© 2010.12

2

    After correcting the original service problem, perform the
following safety checks before releasing the set to the customer:
Check the antenna terminals, metal trim, “metallized” knobs, screws,
and all other exposed metal parts for AC leakage. Check leakage as
described below.

    The AC leakage from any exposed metal part to earth ground and
from all exposed metal parts to any exposed metal part having a
return to chassis, must not exceed 0.5 mA (500 microamperes).
Leakage current can be measured by any one of three methods.

1.

A commercial leakage tester, such as the Simpson 229 or RCA
WT-540A. Follow the manufacturers’ instructions to use these
instruments.

2.

A battery-operated AC milliammeter. The Data Precision 245
digital multimeter is suitable for this job.

3.

Measuring the voltage drop across a resistor by means of a
VOM or battery-operated AC voltmeter. The “limit” indication
is 0.75 V, so analog meters must have an accurate low-voltage
scale. The Simpson 250 and Sanwa SH-63Trd are examples of
a passive VOM that is suitable. Nearly all battery operated
digital multimeters that have a 2V AC range are suitable. (See
Fig. A)

µF

Ω

— BACK PANEL —

AEP, UK models

Canadian model

US model

4-228-507-0s

4-228-507-1s

4-228-507-2s

········································ 4

······························································· 6

········································································ 11

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··································································· 17

······························ 22

6-1. Block Diagram     MAIN Section ································ 31
6-2. Block Diagram     DISPLAY/POWER Section ··········· 32
6-3. Note for Printed Wiring Boards and

Schematic Diagrams ···················································· 33

6-4. Circuit Board Location ················································ 33
6-5. Waveforms ··································································· 34
6-6. Printed Wiring Board     BD Board ····························· 35
6-7. Schematic Diagram     BD Board (1/2) ······················· 36
6-8. Schematic Diagram     BD Board (2/2) ······················· 37
6-9. Printed Wiring Board     HP Board/KEY Board ·········· 38
6-10. Schematic Diagram     HP Board/KEY Board ············ 38
6-11. Schematic Diagram     MAIN Board (1/3) ·················· 39
6-12. Schematic Diagram     MAIN Board (2/3) ·················· 40
6-13. Schematic Diagram     MAIN Board (3/3) ·················· 41
6-14. Printed Wiring Board     MAIN Board (Side A) ·········· 42
6-15. Printed Wiring Board     MAIN Board (Side B) ·········· 43
6-16. Printed Wiring Board     PANEL Section ···················· 44
6-17. Schematic Diagram     PANEL Section ······················· 45
6-18. Schematic Diagram     AC Board ································ 46
6-19. Printed Wiring Board     AC Board ······························ 47
6-20. IC Block Diagrams ······················································ 48
6-21. IC Pin Function Description ········································ 53

······················································ 60

······································· 64

3

COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE WITH
MARK 0 ON THE SCHEMATIC DIAGRAMS AND IN THE PARTS
LIST ARE CRITICAL TO SAFE OPERATION. REPLACE THESE
COMPONENTS WITH SONY PARTS WHOSE PART NUMBERS
APPEAR AS SHOWN IN THIS MANUAL OR IN SUPPLEMENTS
PUBLISHED BY SONY.

LES COMPOSANTS IDENTIFÉS PAR UNE MARQUE 0 SUR LES
DIAGRAMMES SCHÉMATIQUES ET LA LISTE DES PIÈCES SONT
CRITIQUES POUR LA SÉCURITÉ DE FONCTIONNEMENT. NE
REMPLACER CES COMPOSANTS QUE PAR DES PIÈSES SONY
DONT LES NUMÉROS SONT DONNÉS DANS CE MANUEL OU
DANS LES SUPPÉMENTS PUBLIÉS PAR SONY.

This appliance is classified as a CLASS 1 LASER product. The
CLASS 1 LASER PRODUCT MARKING is located on the rear
exterior.

The following caution label is located inside the unit.

Laser component in this product is capable
of emitting radiation exceeding the limit for
Class 1.

CAUTION
Use of controls or adjustments or performance of procedures
other than those specified herein may result in hazardous radiation
exposure.

• Never reuse a disconnected chip component.

• Notice that the minus side of a tantalum capacitor may be

damaged by heat.

• Keep the temperature of soldering iron around 270˚C

during repairing.

• Do not touch the soldering iron on the same conductor of the

circuit board (within 3 times).

• Be careful not to apply force on the conductor when soldering

or unsoldering.

Eksplosjonsfare ved feilaktig skifte av batteri.

Benytt samme batteritype eller en tilsvarende type

anbefalt av apparatfabrikanten.

Brukte batterier kasseres i henhold til fabrikantens

instruksjoner.

Explosionsfara vid felaktigt batteribyte.
Använd samma batterityp eller en likvärdig typ som
 rekommenderas av apparattillverkaren.
Kassera använt batteri enligt gällande föreskrifter.

Paristo voi räjähtää, jos se on virheellisesti asennettu.
Vaihda paristo ainoastaan laitevalmistajan suosittelemaan tyyppiin.
Hävitä käytetty paristo valmistajan ohjeiden mukaisesti.

Lithiumbatteri-Eksplosionsfare ved fejlagtig håndtering.

Udskiftning må kun ske med batteri

af samme fabrikat og type.

Levér det brugte batteri tilbage til leverandøren.

Danger of explosion if battery is incorrectly replaced.
Replace only with the same or equivalent type recommended by
the manufacturer.
Discard used batteries according to the manufacturer’s instructions.

The laser diode in the optical pick-up block may suffer electrostatic
break-down because of the potential difference generated by the
charged electrostatic load, etc. on clothing and the human body.
During repair, pay attention to electrostatic break-down and also
use the procedure in the printed matter which is included in the
repair parts.
The flexible board is easily damaged and should be handled with
care.

The laser beam on this model is concentrated so as to be focused on
the disc reflective surface by the objective lens in the optical pick-
up block. Therefore, when checking the laser diode emission,
observe from more than 30 cm away from the objective lens.

4

The self-diagnosis function consists of error codes for customers which are displayed automatically when errors occur, and error codes which
show the error history in the test mode during servicing. For details on how to view error codes for the customer, refer to the following box
in the instruction manual. For details on how to check error codes during servicing, refer to the following “Procedure for using the Self-
Diagnosis Function (Error History Display Mode)”.

The deck’s self-diagnosis function automatically checks the condition of the MD deck when an error occurs, then issues a three- or five-digit
code and an error message on the display. If the code and message alternate, find them in the following table and perform the indicated
countermeasure. Should the problem persist, consult your nearest Sony dealer.

Perform the self-diagnosis function in the “error history display mode” in the test mode. The following describes the least required procedure. Be

careful not to enter other modes by mistake. If you set other modes accidentally, press the  MENU/NO  button to exit the mode.

1. While pressing the  l AMS L  knob and x  button, connect the power plug to the outlet, and release the  l AMS L  knob and

x  button.  When the test mode is set “[Check]” is displayed.

2. Turn the  l AMS L  knob and when “[Service]” is displayed, press the  YES  button.
3. Turn the  l AMS L  knob to display “Err Display”.
4. Press the  YES  button to sets the error history mode and displays “op rec tm”.
5. Select the contents to be displayed or executed using the  l AMS L  knob.
6. Press the  l AMS L  knob to display or execute the contents selected.
7. Press the  l AMS L  knob another time to return to step 4.
8. Press the  MENU/NO  button to display “Err Display” and release the error history mode.
9. To release the test mode, press the  REPEAT  button. The unit sets into the STANDBY state and the test mode ends.

C11/Protected

The inserted MD is record-protected.

Take out the MD and close the record-
protect slot (page 15).

C12/Cannot Copy

You tried to record a CD with a format 
that the external device connected to the 
deck does not support, such as CD-ROM 
or video CD.

Remove the disc and insert a music 
CD.

C13/REC Error

The recording was not made properly.

Set the deck in a stable surface, and 
repeat the recording procedure.

The inserted MD is dirty (with smudges, 
fingerprints, etc.), scratched, or 
substandard in quality.

Replace the disc and repeat the 
recording procedure.

C13/Read Error

The deck could not read the TOC on the 
MD properly.

Take out the MD and insert it again.

C14/Toc Error

The deck could not read the TOC on the 
MD properly.

Insert another disc.
If possible, erase all the tracks on the 
MD (page 32).

C41/Cannot Copy

The sound source is a copy of 
commercially available music software, or 
you tried to record a CD-R (Recordable 
CD).

The Serial Copy Management System 
prevents making a digital copy 
(page 52). You cannot record a CD-R.

C71/Din Unlock

The sporadic appearance of this message 
is caused by the digital signal being 
recorded. This will not affect the 
recording.

While recording from a digital component 
connected through the DIGITAL IN 
connector, the digital connecting cable 
was unplugged or the digital component 
turned off.

Connect the cable or turn the digital 
component back on.

E0001/
MEMORY NG

There is an error in the internal data that 
the deck needs in order to operate.

Consult your nearest Sony dealer.

E0101/
LASER NG

There is a problem with the optical 
pickup.

The optical pickup may have failed. 
Consult your nearest Sony dealer.