Hello,
I just get a cd player Yamaha same as sony cdp 750. I would replace electrolytics, output caps, put a emi filter, replace some resistor by 1% arround 1541 and opa, diodes may be too.
Questions about psu :
I only see a winding in the secondary for numeric and analogic tension. The diodes evoke a voltage doubler. Isn'it ?
Why psu caps (pre-reg) C203 100uF/204 330uF (analog) and C105 4700uF/106 3300uF (numeric) aren't symetric ?
A new transformer and power supply for analog could be necessary. What do you think about ?
Please take a look.
I can upload other pages of the diagram.
I just get a cd player Yamaha same as sony cdp 750. I would replace electrolytics, output caps, put a emi filter, replace some resistor by 1% arround 1541 and opa, diodes may be too.
Questions about psu :
I only see a winding in the secondary for numeric and analogic tension. The diodes evoke a voltage doubler. Isn'it ?
Why psu caps (pre-reg) C203 100uF/204 330uF (analog) and C105 4700uF/106 3300uF (numeric) aren't symetric ?
A new transformer and power supply for analog could be necessary. What do you think about ?
Please take a look.
I can upload other pages of the diagram.
for C105 and c106, it is because the secondary of the transformer is not used in the same way on the + and on -, the + is used to power two circuits, they have therefore compensated in capacity, I think that C203 and C204 must be part of this compensation.
People who know how to actually read the diagram will be able to be clearer on this subject.
People who know how to actually read the diagram will be able to be clearer on this subject.
Thank you for this start of explanation. I won't have fun changing the values of these capacitors.
Once the capacitors are replaced, I plan to mount another dual op amp in place of this M5218.
But which one given the circuit of this CD player? unit gain or not. The M5218 datasheet doesn't indicate this.
Informed opinions will be welcome. THANKS
Once the capacitors are replaced, I plan to mount another dual op amp in place of this M5218.
But which one given the circuit of this CD player? unit gain or not. The M5218 datasheet doesn't indicate this.
Informed opinions will be welcome. THANKS
Attachments
just a small mod for analog stage from this post https://www.diyaudio.com/community/threads/sony-cdp-68-upgrades.298751/. May be a lme49720 better than 2134
It could be as @huggygood suggests. The current draw from the - and + rails will be very different and it may just be they are the optimum values to meet the specified ripple on the rail.
Another possibility (and this happens with Philips players) is that different time constants are needed to minimise any unwanted sswithc on and switch off behaviour including logic latchups. Sequencing of rails can be very important.
C201 and C202 will be very demanding on their quality (high ripple capacity) so choose any replacements very carefully. Caps used like are common failure points in much equipment.
Yes, any AC coupled output should always be ground referenced. If you omit the muting circuitry don't be surprised if you hear noises on power on, off and perhaps during certain playback operations such as searching etc.
Probably not. I would suggest you try it without the muting under all conditions of operation and then you will know.
I've also spotted something else. Q12 and Q13 between the mute transistors. That looks to be the de emphasis network for CD's recorded with pre emphasis. Those are not particularly common and are usually in my experience Japanese discs. That network relies on the combined series value of the 680 and 620 ohm resistors feeding it.
In all honesty transistor muting and switching as here does not cause any issues and is transparent. When the transistors are off you have only the tiny junction capacitance across the output and the low impedance around it means it has no effect at all on the audio.
I've also spotted something else. Q12 and Q13 between the mute transistors. That looks to be the de emphasis network for CD's recorded with pre emphasis. Those are not particularly common and are usually in my experience Japanese discs. That network relies on the combined series value of the 680 and 620 ohm resistors feeding it.
In all honesty transistor muting and switching as here does not cause any issues and is transparent. When the transistors are off you have only the tiny junction capacitance across the output and the low impedance around it means it has no effect at all on the audio.
Hi, I am fixing the cd player. The c09 and c010 capacitors around the original ic09 are 470uF 6.3V. Is it possible to mount much larger ones in this location: 2200uF 10v panasonic fr ? or is it better to use polymers like kemet a75 560uF 10v ?
Harman is finished, it's very good after all that cleaning.
yupee
Harman is finished, it's very good after all that cleaning.
yupee
I would not recommend altering the value of any rail related caps as this can cause 'race hazard' situations meaning the rise and fall times of the rails can often be important to ensuring that the logic al sequencies properly. Also adding larger values of cap to a series regulator destroys the ability of the regulator to do its job and respond to variations in load current correctly. There is more, the use of low esr caps on the output of a series regulator can sometimes cause stability issues.