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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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I have a Denon DMD-M10 minidisk recorder that will not play disks
recorded on other machines nor will it record on a disk that has been used before. I was able to record on an unused disk which does play. |
#2
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Lucifer wrote:
I have a Denon DMD-M10 minidisk recorder that will not play disks recorded on other machines nor will it record on a disk that has been used before. I was able to record on an unused disk which does play. And....? Try asking a question next time. |
#3
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In article ,
Lucifer wrote: I have a Denon DMD-M10 minidisk recorder that will not play disks recorded on other machines nor will it record on a disk that has been used before. I was able to record on an unused disk which does play. At a guess, I'd suspect that it might be any of the typical faults which can develop in any laser-optical-based disc recording and playback system: - Deteriorating laser (lower output level) - Dirty laser or read-back optics (dust, tobacco or cannabis smoke particles and tar) - Dirty or poorly-lubricated "sled" on which the optical assembly moves - Misadjusted servo tracking system Power-supply problems e.g. deteriorating filter capacitors, loose cables, intermittent contacts, etc. can also be a problem as these devices age. None of the above is at all specific to your recorder model. If you're serious about trying to fix it, I'd suggest getting the model-specific service manual (there's one up on eBay from a seller in Florida - no connection). |
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#5
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In article ,
Lucifer wrote: On Tue, 20 Apr 2021 18:09:04 -0700, (Dave Platt) wrote: In article , Lucifer wrote: I have a Denon DMD-M10 minidisk recorder that will not play disks recorded on other machines nor will it record on a disk that has been used before. I was able to record on an unused disk which does play. At a guess, I'd suspect that it might be any of the typical faults which can develop in any laser-optical-based disc recording and playback system: Thank you for your reply. However minidisk uses magnetic recording and playback similar to a floppy disk. The laser is only used when recording to heat the disk and thus allow it to be altered by the magnetic write head. All of the information I've found on Minidisc, says that it works the other way around. During recording, the laser operates at high power, heating up the magneto-optic layer on the disc above its Curie point. The fluctuating magnetic field from the write head is "captured" by the MO layer as it cools back below the Curie point. During playback, the laser is used (at low power) to sense the magnetic orientation of the MO layer by sensing changes in the polarization of the reflected laser beam (via the Faraday effect). When playing pre-recorded discs (made more like CDs) the laser is sensing reflectivity differences rather than polarization. References: https://www.minidisc.org/minidisc_faq.html (item 9) as well as The Great Font Of Dubious Knowledge (a.k.a. Wikipedia). For more detail, you can take a look at the original Minidisc patent: http://www.minidisc.org/patents/pdfs/US05244705.pdf - the basic descriptions of the recording and playback processes are at the bottom of column 9 and the first part of column 9, on pages 15 and 16. The technical advantage of this dual approach is that the magnetic head doesn't have to "fly" at an extremely low height over the surface of the disc. In a hard drive, the gap between head and media is truly tiny... much smaller than the diameter of a human hair, and often smaller than a particle of tobacco smoke. It has to be this close, in order to be able to read and write very-tiny bits. That would be very hard to pull off successfuly for a removable medium like MD. With MD, the write head can be larger, and further away from the surface. It produces a fairly broad area of magnetic field, but this affects the material only in the tiny area being heated by the laser (and cooling down immediately thereafter). |
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