SONY DE990
Manual de Servicio

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 30 cm away from the objective lens. BEFORE REPLACING THE OPTICAL PICK-UP BLOCK Please be sure to check thoroughly the parameters as par the �Optical Pick-Up Block Checking Procedures� (Part No.: 9-960-02711) issued separately before replacing the optical pick-up block. Note and specifications required to check are given below. � FOK output: IC601 eg pin When checking FOK, remove the lead wire to disc motor. � RF signal P-to-P value: 0.35 to 0.55 Vp-p LASER DIODE AND FOCUS SEARCH OPERATION CHECK During normal operation of the equipment, emission of the laser diode is prohibited unless the upper lid is closed while turning ON the S801. (push switch type) The following checking method for the laser diode is operable. � Method: Emission of the laser diode is visually checked. 1. Open the upper lid. 2. With a disc not set, turn on the S801 with a screwdriver having a thin tip as shown in Fig.1. 3. Press the u button. 4. Observing the objective lens, check that the laser diode emits light. When the laser diode does not emit light, automatic power control circuit or optical pickup is faulty. In this operation, the objective lens will move up and down 5 times along with inward motion for the focus search.

detection lever

detection lever

S801

MAIN board

Fig. 1 Method to push the S801

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