Hi,
If you have necessary tools and test instruments, know safety precaution inbasic troubleshooting try the steps below to solve your problem.
Assuming that the disc is good.
1.Clean the lens. -Sometimes because of dust and any fine foreign objects the optical lens can'tread any disc. If you have a DVD Lens cleaner, play it to the unit. If this isnot available you may manually clean the optical lens. Open the cover andgently clean the eye of the lens by smooth,clean,soft cotton buds. Be carefulwhile doing this, just a gentle stroke only.
2.Check the ribbon - Checkthe ribbon connected to the lens from the main board for
scratch, damage. Once it has anopen line then of course the lens can't read the disc, this is because of themovement of the optical lens back-and-forth. Also try to erase the contact by pencileraser. If you've done the steps above and the symptoms still there then thenext step requires you a little knowledge in soldering technique and readingthe ohmmeter.
3.Check the spindle motor -Check the spindle motor that spin the disc with an ohmmeter. You can test itusing the ohmmeter (x1) even it is connected on the lens assembly.
Good motor - reading should be fairly high and itwill spin.
Bad motor-reading will drop to low resistance and will not spin.
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LINK1
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Hint : Most of my repairedunit the above parts are commonly caused of the problem.
If you confirmed that you have a defective motor then replace it with a newone. Before replacing the new motor you have to check the clearance of the discholder with the old one. The clearance should be the same as the old because ifnot the lens will not read the disc if it is too far or too close.
If the above steps didn't cure the problem, high chance that your optical lenswas faulty.
If youcan't do the job yourself, I would advice you to look for a professional totroubleshoot the symptom.
Also,check if your unit is under warranty period, avail it because the manufacturerwill fix it for free. Don't attempt to open the cover(it will void thewarranty).
Hope Ihelped you.
Have a nice day!
Thanks for using
Fixya.