How loud is loud ?
I'm not really familiar with CDM9 but possible causes of noise would be the focus coils in the pickup and possibly noise from the motor due to AC being present and exciting the windings. Now you say the noise varies from 1'st to last tracks and that ties in with the motor which slows as the disc plays (due to CLV or constant linear velocity). It runs faster at disc start than at the end.
I don't know what type of motor is used (DC or Hall effect) but it might be worth looking at the motor drive voltage on a scope to make sure no excess noise and hash is present. It could be something like a failed cap in the servo motor servo circuit.
The same applies to the focus coil and its drive.
The radial tracking (for the swing arm) I wouldn't have thought would vary with disc position although they can emit a characteristic hf noise when track searching.
I'm not really familiar with CDM9 but possible causes of noise would be the focus coils in the pickup and possibly noise from the motor due to AC being present and exciting the windings. Now you say the noise varies from 1'st to last tracks and that ties in with the motor which slows as the disc plays (due to CLV or constant linear velocity). It runs faster at disc start than at the end.
I don't know what type of motor is used (DC or Hall effect) but it might be worth looking at the motor drive voltage on a scope to make sure no excess noise and hash is present. It could be something like a failed cap in the servo motor servo circuit.
The same applies to the focus coil and its drive.
The radial tracking (for the swing arm) I wouldn't have thought would vary with disc position although they can emit a characteristic hf noise when track searching.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.