Why Philips CD 723 is a bad base for modding

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T

tschrama

Member
Joined 2001
The bug of the CD723
Fiddling around with the player I noticed the existence of a bug:

Actually if, during the first start-up of the player and after plugging it in, we start a play directly by pressing on " Play " without previously switching on the player (using the "stand by" button), the internal digital output is not oversampled. It is really weird, but very handy if you want to try listening without oversampling without changing anything. As soon as the play is stopped, the output switches back to the normal mode (therefore oversampled 4 times). To perform again the test it is then necessary to switch off the player, then to unplug it and to start again the initial procedure.
Click to expand...

Let me see if I get this right... putting in a CD, pull out the supply plug, plug in the supply plug, press play => NoNOverSampling whitout mod?
 
T

tschrama

Member
Joined 2001
Hi,

Thanks you very much for your efforts!

I just tried to get NonOverS but I couldn't get it. The quare wave on my scope still looks pretty oversampled.. I use a homebuild test CD which has a fullrange 1KHz square wave on track 13..

Does the NonOS trick only work with the first track?


Regards,
Thijs
 
J

jkeny

Banned
Joined 2007
The bug of the CD723
Fiddling around with the player I noticed the existence of a bug:

Actually if, during the first start-up of the player and after plugging it in, we start a play directly by pressing on " Play " without previously switching on the player (using the "stand by" button), the internal digital output is not oversampled. It is really weird, but very handy if you want to try listening without oversampling without changing anything. As soon as the play is stopped, the output switches back to the normal mode (therefore oversampled 4 times). To perform again the test it is then necessary to switch off the player, then to unplug it and to start again the initial procedure
Click to expand...


Does this not mean that after the hack is applied this is a bug that has been seen i.e. the machine switches into non oversampled mode (no matter what the strapping configuration) by following this sequence of turning it on?

John
 
J

jkeny

Banned
Joined 2007
Hi Robinet,

Can you clarify some points - is the CD723 bug only on player with hack in place?

Does the bug also apply to CD4000?

Having read the translation I appreciate more the hard work you put into this - your research was very thorough and exectution very clever.

Well done

John
 
J

jkeny

Banned
Joined 2007
Hi Robinet,

Can you clarify some points - is the CD723 bug only on player with hack in place?

Does the bug also apply to CD4000?

Having read the translation I appreciate more the hard work you put into this - your research was very thorough and exectution very clever.

Well done

John
 
C

capslock

Member
Joined 2002
CD-753 with the same problem?

http://www.diyaudio.com/forums/showthread.php?s=&threadid=38768&highlight=

Does the CD-753 have the same issue? It uses the very same 7378 decoder. The DAC is slightly different, a TDA1549, which is also a 4x fs input DAC. A separate digital filter is nowhere to be seen, so I would assume oversampling is also done in the decoder, same as in the 723, and with the very same problems.

Interestingly, the Marantz CD-6000 is the same unit with slightly differnent power supply and output circuits. It is supposed to be very good-sounding as it comes, if you believe the Golden Ears in magazines, and there is even a signature edition of it. Hard to believe, considering it is likely to suffer from the same issue...
 
R

robinet

Member
Joined 2004
ifrance.com/robinetron
Hello everybody !

Can you clarify some points - is the CD723 bug only on player with hack in place?

Does the bug also apply to CD4000?
Click to expand...
Because the hacker overwrite the dac output mode at the very begining of the reading, the bug won't have any effect. So the bug only work without the hacker.

For the second question you should read below :

I just tried to get NonOverS but I couldn't get it. The quare wave on my scope still looks pretty oversampled.. I use a homebuild test CD which has a fullrange 1KHz square wave on track 13..

Does the NonOS trick only work with the first track?
Click to expand...

This NonOS trick work only if the first button pushed after the supply plug is pluged is "play". After the play begin, you could change the track without loosing the NonOS state.
You lose The NonOS state only if the reading is stoped.
With my CD-713 this bug is perfectly repetable. the NonOs mode was identified with a frequency-meter (2 and some Mhz on SCK).

The bad news is I found that they were some differences between the firmware of differents players. For example, my first version of the hacker work with my cd-713 but didn't work with my CD-4000.

Consequently this bug might not work with all player...
 
R

robinet

Member
Joined 2004
ifrance.com/robinetron
Robinet,
Last question - will this version of your hacker work with CD4000?

John
Click to expand...
Of course it works :D
It has been successfully tested on Philips CD-713, CD-723 and Marantz CD-4000. It might even works on Marantz CD-5000 and CD-6000 (I think the control card is mainly the same).

I put the Carondimonio's translation on my web site :
http://www.ifrance.com/robinetron/cd723/hack/hack_e.html

I copy the translation into a clean html file and add few new things like a tiny board to make a clean assembly. I hope Carondimonio won't mind...
 
C

capslock

Member
Joined 2002
Would anybody who is programming the AVR be willing to make another one and send it? I can pay by bank transfer (free within most of Europe now) or Paypal.

Downloading and setting up the software and soldering the programming adapter is no big deal, but easily an evening's project (and there aren't to many uninterupted evenings with a baby).

Regards,

Eric
 
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