Sony CDP-M33 skipping - not the obvious causes

enryfox · 26th January 2021, 09:06 PM

I have "collected" from the recycle centre this mid size CD player Sony CDP-M33. Considering where I found it, it is in excellent cosmetic conditions and also internally is very clean. It has problems though and it is driving me crazy: it randomly skips back and forth in the first three tracks of many CD's.

The pick-up is a classic KSS-240A (still Sony original) but the control loops are "digital" and do the auto calibration. I have thoroughly cleaned the sledge rails, both the steel rod and the white plastic rail; I have cleaned the sledge motor and gears and the pick-up slides on the rails smoothly and with minimal effort. I tried replacing the pick-up with a new replica, but I always get the same result, it skips in the first 10 minutes of playback; after that it plays flawlessly until the outer edge of the disc.

All electrolytic caps are Elna, but none appears to have the slightest hint of leakage; the control board does not have caps at all.

What could be the problem ? I know this player is worth nothing, it is just fun playing with it.

ManoloMos · 27th January 2021, 02:22 PM

When is cold works, when is hot not works... I think it maybe a bad soldering. Look soldering side at servo zone.

percival007 · 27th January 2021, 10:03 PM

Having trouble playing the first Tracks, where it has to spin fastest?

Spindle Motor.

P.

enryfox · 28th January 2021, 01:26 PM

the spindle motor appears to be fine, I have added a drop of watch oil in the bearing and it is very silent and smooth. Moreover the skipping occurs typically after 3 minutes of playback, not at the very beginning.

Just to be on the safe side I have re-soldered all voltage regulators and the socket for the pickup cable on the control board.

I will keep it monitored and see if that *magically* fixed the problem

thanks !

Mooly · 28th January 2021, 02:19 PM

Monitor the sled motor voltage (solder wires to it for easy access) and watch the voltage as it plays. If the sled sticks then the voltage will start to increase until the motor can overcome the friction and the things jolts forward.

Maybe there is a tiny burr on the gears.

26th January 2021, 09:06 PM	#1
enryfox diyAudio Member Join Date: Feb 2019	Sony CDP-M33 skipping - not the obvious causes I have "collected" from the recycle centre this mid size CD player Sony CDP-M33. Considering where I found it, it is in excellent cosmetic conditions and also internally is very clean. It has problems though and it is driving me crazy: it randomly skips back and forth in the first three tracks of many CD's. The pick-up is a classic KSS-240A (still Sony original) but the control loops are "digital" and do the auto calibration. I have thoroughly cleaned the sledge rails, both the steel rod and the white plastic rail; I have cleaned the sledge motor and gears and the pick-up slides on the rails smoothly and with minimal effort. I tried replacing the pick-up with a new replica, but I always get the same result, it skips in the first 10 minutes of playback; after that it plays flawlessly until the outer edge of the disc. All electrolytic caps are Elna, but none appears to have the slightest hint of leakage; the control board does not have caps at all. What could be the problem ? I know this player is worth nothing, it is just fun playing with it.

28th January 2021, 02:19 PM	#5
Mooly diyAudio Moderator Join Date: Sep 2007	Monitor the sled motor voltage (solder wires to it for easy access) and watch the voltage as it plays. If the sled sticks then the voltage will start to increase until the motor can overcome the friction and the things jolts forward. Maybe there is a tiny burr on the gears. __________________ Installing and using LTspice IV. From beginner to advanced.

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27th January 2021, 02:22 PM	#2
ManoloMos diyAudio Member Join Date: Dec 2019 Location: Canary Islands	When is cold works, when is hot not works... I think it maybe a bad soldering. Look soldering side at servo zone.

27th January 2021, 10:03 PM	#3
percival007 diyAudio Member Join Date: Sep 2007	Having trouble playing the first Tracks, where it has to spin fastest? Spindle Motor. P.

28th January 2021, 01:26 PM	#4
enryfox diyAudio Member Join Date: Feb 2019	the spindle motor appears to be fine, I have added a drop of watch oil in the bearing and it is very silent and smooth. Moreover the skipping occurs typically after 3 minutes of playback, not at the very beginning. Just to be on the safe side I have re-soldered all voltage regulators and the socket for the pickup cable on the control board. I will keep it monitored and see if that magically fixed the problem thanks !