SONY DEJ755
Service Manual

D-EJ750/EJ751/EJ753/EJ755/EJ756CK/EJ758CK SECTION 1 SERVICING NOTES
NOTES ON HANDLING THE OPTICAL PICK-UP BLOCK OR BASE UNIT The laser diode in the optical pick-up block may suffer electrostatic breakdown because of the potential difference generated by the charged electrostatic load, etc. on clothing and the human body. During repair, pay attention to electrostatic breakdown 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. NOTES ON LASER DIODE EMISSION CHECK 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 30cm away from the objective lens. Before Replacing the Optical pick-up Block Please be sure to check thoroughly the parameters as per the �Optical pick-up Block Checking Procedure� (Part No. : 9-960-027-11) issued separately before replacing the optical Pick-up block. Note and specifications required to check are given below. Laser Diode Checking Methods During normal operation of the equipment, emission of the laser diode is prohibited unless the upper panel is closed while turning ON the S801 (push switch type). The following two checking methods for the laser diode are operable. Method : Emission of the laser diode is visually checked. 1. Open the upper lid. 2. Push the S801 as shown in Fig. 1 . 3. Check the object lens for confirming normal emission of the laser diode. If not emitting, there is a trouble in the automatic power control circuit or the optical pick-up. During normal operation, the laser diode is turned ON about 2.5 seconds for focus searching.

S801
� FOK output : IC601 yg pin When checking FOK, remove the lead wire to disc motor. � RF signal P-to-P value : 0.45 to 0.65Vp-p

Fig.1 Method to push S801

SECTION 2 GENERAL
LOCATING THE CONTROLS
CD player (front)
1 PLAY MODE button 2 SOUND button 0 Strap holes 3 VOL (volume) +* qa Display 4 'm (AMS/ search) button

This section is extracted from instruction manual.

9 DC IN 4.5 V (external power input) jack

qs REPEAT/ENTER button

5 VOL (volume) � button 6 X (pause) button 7 x (stop)/CHG (charge) button 8 N* (play)/ > (AMS/search) button

qd HOLD switch

qf OPEN switch qg LINE OUT

qh i (headphones)

CD player (inside)

qj G-PROTECTION switch qk Battery compartment

*The button has a tactile dot.

3