CD3300 high pitched squeal at the outer tracks during play, radial servo noise??

[Garten47]

Hi all,

Have a Cd3300, needed the usual CDM recap, ordered the capkit from Martin, all sorted, plays beautifully, tracks found  quick, like new!

BUT, it has now developed a high pitched squeal when jumping to and reading from the outer tracks, its loud enough to be quite disturbing.

It sounds like some players that develop a quite pronounced squeal when seeking track, but much more pronounced, and I then have that continuously during play, but only at the outer tracks…

Like if the CD has 24 tracks is on 22,23,24.

So i narrowed it down to the radial servo, , but cant understand why all of a sudden,… Some people talk about possible sagging of the mechanism, but the laser assembly moves very freely, so no mechanical issue seems to be present.. tried shimmy the disc, but no difference.

I have not adjusted or changed anything, just changed the caps and put it all together again, and it reads everything, burned cd-r, scratched discs, juast aslong as it not in the outer section…

Any thoughts?

Any test I can do to undestand what is going on, does something need lube?, but how could this have happend just by turning the unit upside down a couple of times? (tried to turn it upside down again a few times, but nothing changed)

By the way, i have worked on these and the cd4500 and cdX before, but this fault is new !! :=)

Thanks all

[Garten47]

…After some additional analysis, there seems to be a heat/time component.

When the player has been switched on and playing “for a while” the high pitched noise goes away playing those end of disc tracks.

I also lifted the player and gently angled it in different tilts, that did not lessen, change or remove the squealing.

so something heats up and expands? or something heats up and becomes less viscous?

Thanks!

[Garten47]

It was not heat dependent, I was mistaken, i measured the frequency its spot on 5168Hz, all the time….

Does this bare any significance?

 

thanks

[Dillen]

Perhaps someone messed with the laser current (and focus offset if present) adjustments.
I see this often when desperate owners or untrained service people panic to get the thing going (instead of merely replacing the servo board capacitors).

Martin

[Garten47]

Thanks Martin, Very possible,.but from its known history and looks inside it was fairly untouched, and its beoparts kit i used to recap 🙂 so should be fine…measured both current to the radial servo over the 4.70ohm R3160 and the current to the laser diode, everything looks ok and measure normal between outer and inner tracks. Still these oscillations that makes the radial servo coils “sing” at about 5khz… thinking of supresssing with a small 1nF cap on the L272 opamp output as i cant find the cause, perhaps cure the symptoms… seems unlikely its the motorcoils, but admit im unsure…i have a Philips cd-160 with the same servoboard, not sure its advisable to swap as a test…

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