CD723/753 tweaking!

[ernesternest]

Clock Voltage output.

Hi, found answer in datasheet.
Maxvoltage is 6.5V at any input.

Regards Ernst

 

[akira]

Hi all,

Has anyone an electronic copy of the drive modification webpages ? They seem to have vanished from the sever. I still have to solder some (10% of the componants) and I cannot identify them on my poor paper print of the schematics ...

Please help I would need the full resolution of the schematics and of the component side of the drive PCB.

Thanks

 

[al3700]

Hi all

I read with interest Nuuk`s article in Decibel Dungeon regarding the modification of a Philips CD723, so much so I bought one on ebay for £25. The intention is to do the mechanical mods and use it as a transport in conjunction with a Shek NOS DAC which I am currently running with a Pioneer PD S703. The problems started when I read this post, I admit I do not understand a tenth of what is said here (not anyone’s fault but my own ignorance) but I assume that I need to do the hack when I start the mods?

Will the hack and mechanical mods produce a better machine than the PD S703?
An alternative is to buy a Micromega stage 1. and mod that.
The final question is how exactly do I do the Hack? I don`t have extensive knowledge in electronics so if I have to re-programme eproms etc then I won`t bother (anyone want a CD723?)

I really would like to mod the CD723 but if I am going to get something that is not as good as what I already have. The issue I have with the PD S703 is the sound stage it`s not deep or wide. I have listened to a Micromega Stage 1 and the sound stage extends out beyond the speakers which is what I want to achieve.

Hope someone can help.

Thanks in advance

Alan

 

[nuryev]

cd723 mod

I successfully modded my cd723 simply using the help from the supportive guys on this website. Have since moved on to modifying marantz cd63 and cd67.

 

[jemraid]

Hello all,

I am most of the way through modifying my CD723 and in Nuuk's instructions I came across this, "Please note that the caps 2513 and 2514 (470 pF) in parallel with the outputs are to be removed if you add 820 pF + 470 uH"

Does this mean that the two items to be added are in series across the output, or should they be in parallel as the 2513/2514 caps are.

Thanks - Jim

 

[jemraid]

Hello all,

I have noticed something else, in the text it says remove caps 2513 and 2514 yet it is 3513 and 3514 that are outlined in red ?

An externally hosted image should be here but it was not working when we last tested it.

I think the the 820 pf and the 470 uh inductor should be in series, are the inductors soldered in at points A and C [to the resistor leads] and the caps to the resistor lead at B and to the circuit board at D and then joined ?

Can anyone help, I have already removed 2513 and 2514.

Jim

 

[jemraid]

Hello all [again]

Just to try and clarify the above;

An externally hosted image should be here but it was not working when we last tested it.

May I ask if this is correct ?

Jim

Edit: Looking closely at the circuit above it looks to me that B is actually drilled through the PCB to the track [ground] underneath, is this correct ?

 

[nuryev]

cd723

hi - i tried that mod but it did not make any noticeable difference so I left it out. Also found the instruction and diagram a bit confusing - but then I have no formal training in audio electrical repair.

 

[jemraid]

Dear Nuryev,

Thanks for the reply

May I ask if you orientated the components as in my post 147 and did you drill a hole in the baseboard at B ?

Cheers - Jim

 

[jemraid]

Hello all,

Nuuk has suggested that the RLC modification is not worth doing.

I will replace caps 2513 and 2514.

And hopefully hear what it sounds like this afternoon

Cheers - Jim

 

[nuryev]

Hi Jim
It has been a few years ago - but I do recall that at NO time did I drill any holes in the circuit board. I either replaced components, bypassed by soldering under the circuit board or removed parts .

I eventually left the RLC suggestion out and have to agree with Nuuk that it may not be worth doing. I have since taken it to a friend to audition the CD723 (Marantz CD4000) and he was so impressed so I gave it to him - he practically threw out his newer CD7300 . - it is now in my system as a comparison between standard marantz and modified cd players.
Sorry I could not be of more help with this one. Send me an email and I will try and email you some pics of my mods -if that will help at all.

Good luck.

 

[jemraid]

Hello Nuryev and Hello all,

Thanks for the extra info and for the offer of some pics, I didn't do the RLC mod and put back the original caps.

I turned it on just after lunch and one channel didn't work, some track had broken by the new 10 uf/0.1 uf caps, I soon fixed it with some bare wire.

I've been listening to it on and off for most of the afternoon and everything that has been written about the mods is there. Formerly I listened to a Technics SL-PG520A and when I got the CD723 [£20 on eBay] it sounded much better unmodded, a sound stage which the poor old Technics is incapable of.

The mods have taken this difference up another notch and I must thank Nuuk and everyone whose advice I've found in this thread for the excellent work that allows non-technical people like me to achieve audio standards that would otherwise be unobtainable.

I'm very very pleased indeed and can look forward to hearing my collection all over again

Jim

 

[nuryev]

Hi Andy
Do you have any pics of the TDA1541A in the CD723?

 

[Nicodimdom]

Hi,
May be you will be interested in that. The mods are not made the usual way people (electronicians) usually start with. I didn't make the main mods but added some personal touches and rebuilt everything in a wooden case. The basic conceptions: clock has not been changed. No regulators added but a very strong PI power (roughly 700,000 µ) built specially for the output AOP which is Audio-GD Moon (people usually don't like it too much but at the right place it does better than Burson I previously tried) + a lot of capacitors at the right place. The 2 big condos help the 5v supply.

The result? It beats every modified 723 or 67 like I compared t, being with or without clock, with regulated PS and many commercial machines costing several Kbucks, believe it or not. No stress at all even in the forte, very musical though precise and detailed in a very natural way.A few pictures in my next messages.

 

[Nicodimdom]

Here are a few pics

 

[Nicodimdom]

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Forgot to mention the output transformators and the fact the machine has been treated against MDI

 

[Nicodimdom]

Of course there are some replacements of components for better and/or higher value and some mods under the PCB

 

[shepperd]

Tiens now why does that look familiar? I concur that this machine sounds great, even if it does look rather...out of the ordinary. Many roads to get to the same place.

 

[Nicodimdom]

Salut Shep,
Bon, j'en ai un peu rajouté mais je me suis dit que j'allais quand même me faire le plaisir en montrant mon machin sans trahir Christian.
Ca va?
Thanks for your kind message.

 

[210]

Philips also made the color code mistake(*) of the output op working resistors (+-Ub resistors) in my CD723.
One resistor was right, the other had a much too high value
(*): color code printing from right to left correct, instead from left to right.