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-   -   CD723/753 tweaking! (http://www.diyaudio.com/forums/digital-source/11395-cd723-753-tweaking.html)

Audiofanatic 20th February 2003 05:52 PM

CD723/753 tweaking!
 
Hi Audio tweakers,

gpapag and I (AF), want to start a new thread about tweaking the PHILIPS CD-723/753 CD-Player's.

I'll try to dig-up the schematic within a few days and hope that I'll be able to buy a scanner in this weekend so we all will know what we can do, and how we can do the modifications to this great and cheap CD-Player.


Best Regards,

Audiofanatic!;)

Asen 20th February 2003 06:46 PM

OK

I have some experience with CD721. Brand new it sounded like twice more expensive. After some tweaks - I don't know but... like a pretty expensive CD player.

My system:
CD721
JLH 10W SE Amp
Odin - SEAS Excel speakers
vdHul cabling - D102 Hybrid interconect and CS122 speaker cable.

After all I still think the weakest points in my system are the CD player and the amp (it should be a bit more powerful even though I don't listen to music as loud as it could deliver).

Wombat 20th February 2003 09:41 PM

Here are already some ideas of modding it, that may give you some ideas.
http://www.decdun.fsnet.co.uk/projec...html#cddigiout

I have a 753 myself and only use it as transport.

Wombat 20th February 2003 09:46 PM

Just wanted to show you how cheap you can get one with some luck.

http://cgi.ebay.de/ws/eBayISAPI.dll?...tem=3309370360

And no, that wasn´t me :( i had to pay 43Euro...

gpapag 22nd February 2003 05:52 PM

Originally posted by Wombat
"Here are already some ideas of modding it, that may give you some ideas.
http://www.decdun.fsnet.co.uk/proje....html#cddigiout"

======================================
Dear Wombat
Your help is greatly appreciated
Regards
George

Asen 22nd February 2003 08:46 PM

Quote from this link - http://www.decdun.fsnet.co.uk/project.cd2.html :
Replace the three 100 ohm resistors (3502, 3503 and 3504) with 22 ohm values. This reduces the jitter on the signal going to the DAC and also improves the wave shape.


In my CD player CD721 these three resistors are 220 ohm. Can I reduce the values without harm? To what value? The DAC they lead to is TDA1545.

Thanks

Tazzy 22nd February 2003 09:10 PM

I've got a 624 connected to a Cambridge dacmagic 2 and I'm also very interested in improvements :)

peterr 24th February 2003 11:38 AM

Quote:

Originally posted by Wombat
Here are already some ideas of modding it, that may give you some ideas.
http://www.decdun.fsnet.co.uk/projec...html#cddigiout

I have a 753 myself and only use it as transport.

this site is from DIY Audio member Nuuk So he might be able to give some more tips.

Btw I just bought one as well. 50,- almost new. So I am very interested in this thread suddenly:)

massimo 24th February 2003 01:05 PM

If somebody is going to perform the mods detailed in http://www.decdun.fsnet.co.uk/project.cd2.html
pls note that in the "Modifying the CD transport PCB" section there's a mistake and should be read "remove C2890 and R3897, then short R3896".
Otherwise you totally isolate the S/PDIF output of the Signal Processor IC.

Secondly, even if not mentioned in the "Modifying the audio output section", caps 2513 and 2514 (470 pF) in parallel with the outputs are to be removed if you add 820 pF + 470 uH to form an RLC filter.

Last but not least, check the value of resistors 3537 and 3538 (RC filter with caps 2521 and 2522 in the PS of the dual opamp). They should be BOTH 220 ohm. In many units, one of this resistor is 1.2 k.
The very similar band code: red-red-brown (220) vs. brown-red-red (1200) can explain this silly mistake in production.

peterr 24th February 2003 01:10 PM

would something like this be an option? cd enhancer


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