CDP333ES skips

[jurijvi]

Hi

I have an old and seldom used Sony CDP333ES. It randomly skips while playing. I opened it and gave a clean to the cd mechanism (not much to clean though). What could that be?

Thanks

[Mooly]

General things to check for any CD player problem,
1. That the lens is clean and bright looking.
2. That the pickup can move freely... old grease on gears is a problem and the only way to be sure is to clean/wash it off... which means dismantling. If you connect a DVM across the sled motor drive on the pcb and monitor the voltage a rise without the sled moving shows it has stuck, and when the voltage is enough to overcome friction it "jerks" forward.
3. Spindle motors can wear... mechanical and brush wear.

And you also should use an oscilloscope to confirm the quality and amplitude of the signal coming off the disc.

[jurijvi]

Hello, thanks for the reply.

I've cleaned the lens, carefully. As for the pickup, I believe it works on linear motor, there are no gears. It still jerk now and then even with new cds.

The PCBs all look clean and no sign of capacitor leakage or similar.

Sigh.

[jurijvi]

Anyone has dealt with the Sony CDP X333ES player?

[Mooly]

If it is a linear motor it should be very free to move by hand (with the power off)
Also does the CD rotate with no "wobble"... look at it edge on.

It may be a failing pickup, that's why a 'scope check is important to confirm it

[jurijvi]

Ok, I've checked some TP and levels seems to be ok. The RF signature is in the pictures. I don't know if it's a good signal or not, is the first time i troubleshoot a cd player.

Is the RF signal of good quality? Service manual mentions 1.2Vpp (+0.2 -0.4).
The signal I get is 0.8Vpp and has an offset vs gnd of 0.5V.
According to the service manual the Vpp is fine, but I'm not sure about the offset (it's not mentioned).

Any advice?

[Razorblade]

Looks good to me at least better than what my unit produces :/
Have a look at the waveform in my thread, yours look really good

[Mooly]

Hi jurijvi,

It is possible the amplitude is a little low.
1.2 Volts peak to peak is typical for Sony (and many other players), you say it is nearer 0.8, and your pictures show around 1 volt if you are on 0.5 volts per division.

So you have to be sure on that... I take it you are on the correct test point etc.

As to the "quality" of the signal... the "diamond" shape at the center has to be clear and well defined with minimal jitter which will make it look "blurred".
There should be minimal "bounce" in the signal too... if it rises and falls that's a sign the disc isn't sat true on the platter.
The DC offset is normal.

I would look again at the amplitudes.

What is the pickup type in this player ? Most KSS series pickups have the laser current marked as the last three digits of the pickup serial number so 45213392475 would mean 47.5 ma current. There is usually a low value resistor on the laser drive circuit on the PCB that you can measure the volt drop across and calculate the current. If it's high by 10% or more that is a sign the laser has deteriorated.
Low amplitude can be caused by internal contamination of the optics too... particularly if it's from a smoky atmosphere.

If you can measure the "tracking" error signal somewhere while it's playing ( the DC signal across the tracking coils on the pickup) that may give a clue as to whether it's mechanical or not. If the voltage suddenly starts to rise that means the lens is moving to correct a positional error and that the sled has stuck. Use the scope on DC to measure.

[jurijvi]

Hello Mooly,

thanks for the reply. I've taken a clearer snapshot of the RF (the TP is clearly marked on the pcb and the service manual).
The amplitude of the signal is clearer. I confirm it's around 800 to 900mVpp. I've sharpened the capture and the diamond looks fine, however I've highlighted a part where the signal is not that clear. I believe there are fluctuations in amplitude.
In the previous snapshots I've also highlighted a hole in the signature.

From what I can see while probing the signal, the waveform is not “that” stable.
Just to recall, the skipping occurs randomly, and not always.

I will check the type of pickup later tonite.

[georgehifi]

If you end up thinking it's the laser, KSS240A not is not too hard to get yet unlike KSS151A, try to get original Sony instead of Chinese copies. Might as well give the laser output pot a "little" boost to see if that fixes it, if so it's only a temp fix before a new one is needed.
Cheers George