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Old 3rd June 2011, 01:41 PM   #61
oshifis is offline oshifis  Hungary
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I read somewhere that the CDM-1 tracking uses 660 Hz modulation, but I can't remember the details. Is perhaps that "oscillation" you hear?
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Old 3rd June 2011, 03:06 PM   #62
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It is this oscillation which is audible, I think it is 600Hz or 650Hz which the TDA 5709 uses. It is not caused by the chip being faulty though....it is wear in the motor spindle I think. If the CD clamp was made more rigid with regard to centering then this would cure the problem I think, however it's difficult to alter this being plastic.
The TDA5709 chip can be adjusted by using different capacitors and resistors, however the data sheets which I have seen do not explain the exact workings of this, so again, this is difficult to experiment with and you need quite tight tolerance capacitors and resistors....I think the damping method may work, probably adding a damping ring to the CD clamp....just trying to find a suitable piece of rubber or felt to use......will post my results....
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Old 5th June 2011, 02:34 PM   #63
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650Hz is the frequency used by the TDA5709. I have not managed to add any damping it's just too awkward to do. I am going to fit a miniature bearing (MR63ZZ) to the motor shaft which will not allow any play as I shall use a bearing bond to fix the shaft to this if needed. These bearings are used in model helicopters and are quite cheap to buy off ebay and similar and can be run up to several thousand RPM which is well above what is needed (520RPM)......hopefully this will work....or else it's the recycling skip for this player...shame.
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Old 6th June 2011, 08:25 AM   #64
poynton is offline poynton  United Kingdom
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Oh, please !! Not the skip !!

Let me have it !!


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Old 6th June 2011, 03:58 PM   #65
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Old 7th December 2012, 12:40 PM   #66
oshifis is offline oshifis  Hungary
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Resurrecting this old thread:
There is no Focus Bias adjustment in the Philips CDM-1, unlike at Sony mechanisms (and no Tracking Offset, Tracking Gain either). The only adjustments are Laser Output, Focus Offset, and Focus Gain. Also the RF preamplifier is a thick film unit on a ceramic substrate. Does it mean there is no way to adjust the eye pattern? Perhaps the mech is so stable there is no need to adjust anything.
I am asking it because I want to make my Marantz CD94 be able to play CD-R reliably.
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