I'm starting a new thread to focus and clarify the problem(s) with the CDM-1 in this Magnavox FD2040.
Symptoms: Random difficulty reading certain tracks on different discs. Sometimes it's near the beginning of the disc, sometimes further in, and other times near the end. It will skip and/or act like the Search button is being pressed, i.e. playing in a speeded-up fashion. After a moment or two of this, the laser will go back to the beginning of the track in question and try to play it again. The other symptom is that either the spindle motor or radial drive motor (hard to tell which) is very noisy. The nature of the noise is pretty much what's described in this thread.
Now after several weeks of observation, the only variable I've found that affects the symptoms is leaving the unit powered on. If I leave it powered on (not playing, just idle) for an hour or two, it has no problem playing discs that were previously an issue. In addition, the motor noise is completely gone. So my first assumption would be a failing transistor or bad solder joint on either one of the laser boards or the larger servo board, which I can try to pinpoint with hot air and freeze spray. If anyone with more familiarity with the CDM-1 has a sense of where to narrow my search, please chime in.
Symptoms: Random difficulty reading certain tracks on different discs. Sometimes it's near the beginning of the disc, sometimes further in, and other times near the end. It will skip and/or act like the Search button is being pressed, i.e. playing in a speeded-up fashion. After a moment or two of this, the laser will go back to the beginning of the track in question and try to play it again. The other symptom is that either the spindle motor or radial drive motor (hard to tell which) is very noisy. The nature of the noise is pretty much what's described in this thread.
Now after several weeks of observation, the only variable I've found that affects the symptoms is leaving the unit powered on. If I leave it powered on (not playing, just idle) for an hour or two, it has no problem playing discs that were previously an issue. In addition, the motor noise is completely gone. So my first assumption would be a failing transistor or bad solder joint on either one of the laser boards or the larger servo board, which I can try to pinpoint with hot air and freeze spray. If anyone with more familiarity with the CDM-1 has a sense of where to narrow my search, please chime in.
I would suspect a failing/leaking capacitor in the Focus control. Too much focus curren places the lens too far one way or the other causing noise, a bit like a loudspeaker does.
Replace the capacitors on the control board, lots of information about that online and never adjust the laser power. If you do it is likely to become damaged if you do not own a laser power meter and have the required training.
Replace the capacitors on the control board, lots of information about that online and never adjust the laser power. If you do it is likely to become damaged if you do not own a laser power meter and have the required training.
