Open the machine cover, screw machine machine among heart under cover of the four screws, take the plane to heart cover, can see the whole laser components and the spindle motor, etc. Out first to make the tray, then let the tray into, can see the DVD laser head to the main shaft in the direction of the objective lens has raised focused search action, but no red laser laser injection (normal should have a bright red laser injection). Because there was no laser, natural cannot read disc, thus can be initially determined DVD laser or laser driving circuit is abnormal. u8mservice manual download site
Refer to panasonic A300 circuit principle diagram, that such as the laser driven mainly by Q5001 circuit is complete. Q5001 in machine heart on the right side of the reverse of the motherboard, unscrew the four screws of the fixed motherboard, unplug the mainboard to jack board after a row between the lines, the main board to the machine direction of the heart can be flip, Q5001 can be found at this time. Q5001 of panasonic A300 machine (B1115 triode) as the patch encapsulation, appearance is the diagram below, parameters for: 60 v, 1 a, 2 w, 120 MHZ, Si, PNP. Work properly when the foot voltage is 4.95 V, e respectively is 1.6 V, b c is 4.67 V (panasonic A300 machine measured values). Voltage electricity check Q5001 each foot, found that c voltage is extremely low, only 0.48 V. Doubt Q5001 open circuit between e and c, it will be removed. When using point soldering iron unsolder Q5001, Q5001 (B1115) split into two pieces, a piece on the mainboard, another piece, confirm Q5001 have been damaged. u8mservice manual download site
Because B1115 cannot be bought, decided to use the VCD machine commonly used B772 pipe by substitution, and success. B772 parameters for: 40 v, 3 a, 10 w, Si, PNP, in addition to the pressure slightly low, other parameters are better than B1115. In fact, 40 v of the location of the pressure in the Q5001 has more. Because B1115 is different from the appearance of B772 encapsulation, actual substitution, cannot be B772 directly into the motherboard, it should be B772 welding on soft line respectively, and the three legs and then the other end of the cord welding on the spot of Q5001 respectively, pay attention to don't wrong polarity. B772 with electrical tape finally and soft lines of solder joints, metal tube feet all glue, lest meet and cause short circuit or motherboard chassis.

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