Philips CD player developing clicks -> where to get CDM 9 mechanism?

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I have Philips CD-931 CD player, the audio section I tweaked a long time ago.
Some time ago, there were clicks and sometimes even random jumps during the first tracks of some CDs, particular when the chain had just been switched on. When the CD-player no longer sat on top of the power amp, the problem got worse.
The CD-931 was one of the first players to have digital servo loops, so there are no tracking, focus, ... pots to tweak. Also, it was one of the last players to use the rotary arm mechanism. It wasn't the cheapo variety found in CD-6xx players but the compact, full metal version developed for car players.
Intreaguing were the temperature dependence and the fact that skipping occured predominantly on tracks 1 and 2. I suspected some mechanical tracking problem but all parts moved easily, and the output from the tracking servo amp was always well within 20% of its possible swing. Next I looked at the HF signal after the input amplifier. The eye diagram looked healthy enough. So what could be the problem?
Next I looked at the supply rails and grounding. While the tray driver amp had heavy local decoupling, the tracking and servo amps had poor decoupling, and the laser diode signal processors had no decoupling to speak of. The grounding scheme was a joke, the feedback or reference ground of most signal and servo amps being highly contaminated. So I cleaned up supply and grounding. The reward: trouble free operation and a more relaxed sound. Great!
But then... a couple of months later, the skipping started again. Some CDs were always more troublesome then others. Skipping was always on the first tracks only. Some days, everything was ok, the next the same CD would skip. There was no apparent correlation to room temperature, humidity, mains voltage, ... Finally, it became so bad I could no longer use the Philips :(
So my working theory is now that somehow the laser diode is giving up slowly (but I do not yet see why skipping would be worst on the first tracks).
I bought a Harman Kardon FL-8370 but returned it because it sounded awful. Before I buy some other player I might want to try to buy a new mechanism. To my understanding, production of the CDM 9 was ceased long ago. Does anybody have an idea where to get the mechanism or maybe only the pickup unit?

Thanks in advance,
Eric

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Topic - Philips CD player developing clicks -> where to get CDM 9 mechanism? - capslock 11:50:56 01/07/02 (3)

Re: Philips CD player developing clicks -> where to get CDM 9 mechanism? - stelios 09:06:32 01/08/02 (1)

Re: Philips CD player developing clicks -> where to get CDM 9 mechanism? - capslock 01:32:37 01/09/02 (0)

Re: Philips CD player developing clicks -> where to get CDM 9 mechanism? - Anthony 20:56:55 01/07/02 (0)

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