Help in modding Sony CDP-S41

Salar · 14th June 2009, 07:41 PM

Hello,
I will probably use the transport and serveo circuitry of the Sony CDP-S41 (a midsized CD-player) for my DIY-CDPlayer, because KSS-240A lasers of this CDP are easy to get.
Also, he cdp-S41 can be easily hacked with a SPDIF out.
But one thing troubles me:
The spindle-motor is very weak even though it is a
standard Mabuchi RF-1140, which can be found in many players.
Touching the rotating CD very gently immediatly leads to dropouts.
I have two CDP-S41, both share the same weakness.
I guess the current of the servo circuitry can be raised?
Any advice?
Service manual for the CDP-S41 can be easily downloaded in the web, but I can post it as well...
All the best,
Salar

skyraider · 15th July 2009, 08:29 AM

Hi,

I recently moded a similiar player. The output stage went straight to passive I/V and into SRPP tube stage. Sound is very good.

Have you re-caps your PS?

Chhers.

Salar · 15th July 2009, 08:42 AM

Hello skyraider,,
no, no recap of the power supply. What about your player? The same weak motor?
All the best,
Salar

Mooly · 15th July 2009, 04:40 PM

Spindle motors are weak. They don't have to respond to any changes in mechanical load when playing, the only exception is when track searching.
Providing the motor isn't faulty it's a non problem.
To do what you are suggesting is not just a question of "raising the current". To make it more tolerant of increased loading (this is just for info... there is absolutely no reason to attempt this) you would probably end up altering the characteristics of the servo entirely. It's designed as "whole" the characteristics of the motor are part of the design brief. To alter things could well upset the stability of the servo.

Salar · 15th July 2009, 05:36 PM

Hello Mooly,
thanks for the response. I got two CDP-41s, both take some time to skip from the first to the last t track, I assume, because the spindle motor can´t react so quickly.
Foe my DIY-Transport, I would like to stick the shaft of the spindle motor through an extra bronce bearing for steady work, but it will break the motor a bit. This was not a problem on my Nakamichi player, because it had a strong servo circuitry. An the Nak uses the same motor as the CDP-S41, a standard Mabuchi RF-310-11400. But in the CDP-S41 it will be a problem...

Mooly · 15th July 2009, 06:05 PM

Can't really advise on adding an extra bearing, but as to track jumps all the three servos (spindle, tracking and focus) have to work together. The sled is moved in "100 track jumps", reading the subcode, and the spindle motor has to either speed or slow depending which "way" the track jump is. The subcode is then read and the system control determines the next action, another "100 track jump" and so on untill the exact correct spot on the disc can be located. The internal resistance of the motor will determine to a large extent how quickly it can be "slowed" anyway, if you just remove the voltage the mass of the disc will keep it revolving, if you alter the voltage from a "zero output impedance driver" the motor will slow much quicker, but that's determined by the internal resistance.

14th June 2009, 07:41 PM	#1
Salar diyAudio Member Join Date: Feb 2006 Location: Berlin	Help in modding Sony CDP-S41 Hello, I will probably use the transport and serveo circuitry of the Sony CDP-S41 (a midsized CD-player) for my DIY-CDPlayer, because KSS-240A lasers of this CDP are easy to get. Also, he cdp-S41 can be easily hacked with a SPDIF out. But one thing troubles me: The spindle-motor is very weak even though it is a standard Mabuchi RF-1140, which can be found in many players. Touching the rotating CD very gently immediatly leads to dropouts. I have two CDP-S41, both share the same weakness. I guess the current of the servo circuitry can be raised? Any advice? Service manual for the CDP-S41 can be easily downloaded in the web, but I can post it as well... All the best, Salar

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15th July 2009, 08:29 AM	#2
skyraider diyAudio Member Join Date: Jan 2004 Location: malaysia	Hi, I recently moded a similiar player. The output stage went straight to passive I/V and into SRPP tube stage. Sound is very good. Have you re-caps your PS? Chhers.

15th July 2009, 08:42 AM	#3
Salar diyAudio Member Join Date: Feb 2006 Location: Berlin	Hello skyraider,, no, no recap of the power supply. What about your player? The same weak motor? All the best, Salar

15th July 2009, 04:40 PM	#4
Mooly diyAudio Member Join Date: Sep 2007	Spindle motors are weak. They don't have to respond to any changes in mechanical load when playing, the only exception is when track searching. Providing the motor isn't faulty it's a non problem. To do what you are suggesting is not just a question of "raising the current". To make it more tolerant of increased loading (this is just for info... there is absolutely no reason to attempt this) you would probably end up altering the characteristics of the servo entirely. It's designed as "whole" the characteristics of the motor are part of the design brief. To alter things could well upset the stability of the servo.

15th July 2009, 05:36 PM	#5
Salar diyAudio Member Join Date: Feb 2006 Location: Berlin	Hello Mooly, thanks for the response. I got two CDP-41s, both take some time to skip from the first to the last t track, I assume, because the spindle motor can´t react so quickly. Foe my DIY-Transport, I would like to stick the shaft of the spindle motor through an extra bronce bearing for steady work, but it will break the motor a bit. This was not a problem on my Nakamichi player, because it had a strong servo circuitry. An the Nak uses the same motor as the CDP-S41, a standard Mabuchi RF-310-11400. But in the CDP-S41 it will be a problem...

15th July 2009, 06:05 PM	#6
Mooly diyAudio Member Join Date: Sep 2007	Can't really advise on adding an extra bearing, but as to track jumps all the three servos (spindle, tracking and focus) have to work together. The sled is moved in "100 track jumps", reading the subcode, and the spindle motor has to either speed or slow depending which "way" the track jump is. The subcode is then read and the system control determines the next action, another "100 track jump" and so on untill the exact correct spot on the disc can be located. The internal resistance of the motor will determine to a large extent how quickly it can be "slowed" anyway, if you just remove the voltage the mass of the disc will keep it revolving, if you alter the voltage from a "zero output impedance driver" the motor will slow much quicker, but that's determined by the internal resistance.

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