Before the maintenance and analysis disc does not rotate, the reasons for the failure of, TDAl302T 7 feet to get high level voltage, open the laser power switch, power by the 17 foot into, from 16 feet in the output, skinhead supply power, laser head luminescence, the optical for vertical shoot upward, in the focusing and tracking coils with complete automatic focusing and automatic tracking of motion tracking. If the VCD disc bin that read EFM signal, photoelectric induction current by the foot of the TDAl302T20-24, in its internal complete amplifying and filtering from the output unbalanced RF signal to the FOK detection circuit. The microprocessor has a servo movement of the change of the level, to determine the focus of success.

Measuring TDAl302T16 feet around 4V voltage, the foot has no high level switch control voltage, 17 feet have a 5V supply voltage, the foot has no 0.6V rise to about 3.1V voltage. When the voltage is normal, the fault may be in the FOK detection circuit. The machine failure for 7 TDAl302T feet without high level switch control voltage (in the measurement of voltage variation is about 0V-0.28V change, so the laser head without power supply. Check the foot before the components are normal, after replacing the TDAl302T fault still. Considering the cost of the main board is too high, I am in the TDAl302T17 pin and 16 pin on the 13 0.5W resistance to force the laser, the results of failure. As the 5V power supply is controlled by power supply. So there is no need to improve, the laser head is not affected. If the 5V is not a power controlled power supply, can consider to add a pole in TDAl302T and foot control tube.

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