I picked up an Schneider DVD 857 player at a car boot sale for £3.
I got home connected it up to my tv and tried to play a dvd in it. But it would not play it. The disk would spin for a while and then stop with the player saying NODISK. I tried using a cleaning disk but this did not work,I Always liked a challenge so I opened it up and as far as I could tell all the circutry is in good order no burnouts or loose wires. I tried gently cleaning the lazer lens with a cotton wool bud and some metholated spirit but this did not work. I tried a few different disks in it and found the player will happily play Audio disks,MP3,MP4 and Photo disks (JPEG) but not DVD disks.
My next best guess is that it might be a problem with the software rather than the lens. Unfortunately I do not have the Instruction manual for the player and I have been unable to locate anything about the player on the internet so I do not know if there is anyway of troubleshooting or even resetting the player or where to go to download the latest firmware for the player. If anyone can help me I would be gratefull as I have hit a bit of a dead end and am not sure what next to try or where to look.
The problem is the optics assembly. DVDs require a difference laser level than CDs to play correctly. The most common symptom of failing optics is the ability to playt CDs but not DVDs. Unfortunately, I think you have a dud.