"NO DISC" DISPLAY TO DISC PLAYERS - 2

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     The second chance to show no disc display is due to the fault to its laser pickup unit [optical pickup unit] itself.  Laser beam will be generated from the unit may get weak by time.  If the intensity of laser beam decreases, the modulated reflective beam stream from the reflecting surface of the Disc will also go weak, and the video processor section and system control section won't get sufficient signal to process.  This situation might cause to "No Disc" display.

     There are two main causes for this fault.  A dirty disc or dusty laser pickup lens. Insert a good new burned disc into the player  and see whether the player reads it or not.  If reads, check the disc which the player can't read for any damage or dirt.  It is very easy to a disc to get damaged.  There shouldn't be any hard scratches on disc.  To check the disc, hold it against light and see whether there is scratches that can pass light through.  If there is such scratches, or dots, such discs can't be read by the player.  Discard it.

     If a new disc too do not reads, the laser pickup unit shuld be suspected.  But before repalce it, insert a lens cleaning disc [can be bought from most of the electronic spare part selling shops], and play it for at least two times.  If the fault is due to dust or dirt, the cleaning disc will remove it, and the player will be OK.

     An other fault for this is, with a faulty strip wire, that connects the laser pickup unit to main processing board.  Unlike normal wires, this is a special type strip wire.  The conductors in it are carbon traks instead of copper strands.  As this strip wire have to move along with laser pickup unit, as it reads the disc, it may damaged by broken conductors. In some brand of sets, this strip wire will be attached to laser pickup unit by manufacture, and thus cannot be replaced alone.  If the strip wire is found faulty, the entire laser pickup unit should b repalced.  See such a type here.

     For others, the strip wire will be a seperate part, which can be replaced. You cll pull it out from both ends, and can reinsert new one in place.  Care should be taken when replacing strip wire, as it can be easly damaged by excess pressure.

     Here shows a DVD mechanism with its laser pickup unit and sled motor.  See the laser pickup unit has no  strip wire attached to it here.  Ths strip wire is a seperate part.  you can see a small flat socket with a pull-out lock at the right side of the laser pick up unit here.  To insert the strip wire. just relaease this lull out lock by hand [ pull it outwards], place one end of the strip wire into it, and press the lock by push it in. similar fitting will be there at the main baord too, to connect the other end of the strip wire to it.

     It is best to replace this strip wire first, before replacing the laser pickup unit. All these parts are availabel from most of the electronic spare part selling shops at your town. If jerking of picture occurs frequently while playing, check the pitches of gear wheels, that moves the laser pick up unit by its rail, for any dust particles.  Clean them with a type writer cleaning brush. You can see the two  gear wheels here, engaged to a main motor gear [small one]. 
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