Hello everybody, i have the "no disk" problem on my philips cd721 and i have been trying to fix it for a good amount of time i have once seen a video of another cd player with the same symptoms as me and the guy recommended doing a screw part where it would give more power to the laser
What i have tried/done
Disassembled the entire thing
Replaced the belt
Tested with multiple known working cds while it was opened so i can investigate
I have done no mods to and will not buy anything for the repair
It is not second-hand
Can anyone guide me to the solution above or any other one
I have a bit of understanding of how cds are read but i have not repaired any other cd player
Thanks for helping me 🙂
What i have tried/done
Disassembled the entire thing
Replaced the belt
Tested with multiple known working cds while it was opened so i can investigate
I have done no mods to and will not buy anything for the repair
It is not second-hand
Can anyone guide me to the solution above or any other one
I have a bit of understanding of how cds are read but i have not repaired any other cd player
Thanks for helping me 🙂
Hi,
Clean up the objective lens (top and bottom), and the prism, as per: https://www.diyaudio.com/community/threads/stripdown-clean-of-cdm12-4.118902/post-2063355
This made the lens able to detect the disk for me. I didn't even have to try cleaning-up the laser diode, only the objective lens and the prism.
After that, the unit would skip a lot. I had to clean up the CDM12 mechanism from the old lubricant and apply some grease as per: https://retrostuff.org/2021/07/27/philips-cdm-12-1t-laser-sledge-replacement/
It would still skip a little, especially at the end of the disk, until it ran smoother and smoother.
Btw, for anyone falling into this place as I did when I searched for "CD721 No disk", I got the service manual from https://www.electronica-pt.com/esquema/esquemas-dvd/philips-dvd-ht-schematics/philips-cd721-51355/
Those instructions were also helpful to dismantle the unit: https://www.audiovintage.fr/leforum/viewtopic.php?t=56459.
Many thanks to the maintainers and members of this forum, and other forums, for providing such invaluable material online. This helped me not throwing away a device that was in very good condition otherwise.
Hope this helps.
Clean up the objective lens (top and bottom), and the prism, as per: https://www.diyaudio.com/community/threads/stripdown-clean-of-cdm12-4.118902/post-2063355
This made the lens able to detect the disk for me. I didn't even have to try cleaning-up the laser diode, only the objective lens and the prism.
After that, the unit would skip a lot. I had to clean up the CDM12 mechanism from the old lubricant and apply some grease as per: https://retrostuff.org/2021/07/27/philips-cdm-12-1t-laser-sledge-replacement/
It would still skip a little, especially at the end of the disk, until it ran smoother and smoother.
Btw, for anyone falling into this place as I did when I searched for "CD721 No disk", I got the service manual from https://www.electronica-pt.com/esquema/esquemas-dvd/philips-dvd-ht-schematics/philips-cd721-51355/
Those instructions were also helpful to dismantle the unit: https://www.audiovintage.fr/leforum/viewtopic.php?t=56459.
Many thanks to the maintainers and members of this forum, and other forums, for providing such invaluable material online. This helped me not throwing away a device that was in very good condition otherwise.
Hope this helps.
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