I have a Silvercrest DVD player that was also giving the 'bad disc' message for all DVDs. I repair electronic goods so decided to try and fix this one rather than buy another despite the cheap price. The problem is the spindle motor being a bit groggy, usually because of dried-up lubricant and/or dirt. The outcome is that the motor doesn't spin properly, and so the player gives up trying to read the disc and claims it is a 'bad disc'.
The solution I use is this: unplug the player (NEVER work on them with them plugged in - SAFETY), unscrew the case screws and remove the lid. Note where all the plastic cable connectors go and then unplug them so that the disc carriage can be removed. Peel back any foam stickers placed on the top of the plastic cover that spans the carriage and has a disc in the middle that engages with the spindle motor, and undo the screw beneath each and remove the cover. Now gently push the laser into a position where you can get to the flex cable that connects to the laser assembly, pull the retaining clip out a bit to release the flex and gently pull the flex out of the connector, If it doesn't move, the plastic clip that pushes into the connector and applies pressure on the flex isn't pulled out enough. They break easily, so be careful with it and remember that the clip does not come out of the connector completely, it just moves back a couple of millimetres. Remove the 4 screws holding the carriage to the player's chassis and remove it. Now turn it over and locate the little motor that spins the disc (spindle motor) and on the underside of the motor you'll see there is a small hole. Get a can of 3-in-1 oil or similar, attach the little red tube that comes with them and stick the end of the tube over this hole and spray a good amount of oil into the motor. Now get a 9V battery and attach some wires to it and press the wires onto the motor terminals which should be clearly marked as positive and negative - attach them correctly, positive to positive, etc. Make sure the connector that goes to this motor isn't still connected to any board inside the player, otherwise you're about to send 9V into the circuitry and some ICs can be very delicate to highish voltages at the wrong pins.
Use the battery to spin the motor for a while just to spread the oil about and for it to throw out all the excess. Next, use a cloth and alcohol or meths to wipe up all the oil that span out of the motor and got over the carriage and tray. Doesn't hurt to put a squirt of oil on the laser carriage rails either (metal rods the laser carriage runs on) although white grease is best (can get 3-in-1 oil and white grease in a spray can from Wilkinsons). I would also recommend very carefully using a corner of clean cloth wet with alcohol to clean the laser lens, just to remove any dust that might have been there already and also any oil splatter that may have got on it. It's delicate so be gentle, but don't treat it like it's made of powder either - get it clean. Oh, and don't ever do what some people have done when they don't have alcohol - don't use vodka or anything similar. The alcohol content may be quite high, but the sticky residue the other muck in it leaves will do more harm than good, especially on a lens. It'd also attract and stick dust to the lens.
After clean-up is complete, put everything back together and give it a try, but ensure the top cover is back on unless you want to risk eye exposure to the laser, which is not recommended. All going well, it should now work. If not, ensure that more oil hasn't spattered the laser lens and that you've reseated all connectors into the right sockets and that the laser lens flex cable has been FULLY pushed into its connector block on the laser assembly before you pushed the plastic clip back in to hold it in place. It's tricky to connect/remove these very thin film flex cables, but with practice it becomes easier - the biggest mistake people make is not pushing the flex far enough into the connector before pushing in the plastic clip.
Hope this works for at least some people!
on Dec 18, 2008