Modding a Marantz CD40

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#21
Just corrected the schematic again lol... now it must be correct at last... it had mistakenly the clock connecting to pin 25, instead of pin 26 (XIN) of 7310. I didn't notice it when building he circuit, because I automatically chose the right pin, due to the way they are connected lol...

Phil, very interesting what you say about the power supply. So, probably that's the next mod I'll do to the player one day when I've time... but then it'll be with the LT1963... it really convinced me when I used it in the playstation player... only disadvantage is that it's not so easy to get, and quite expensive (5 euros each one).
 
#22
Thanks a lot

joydivision said:
Robo:
Just sent the manual to you.
I wouldn't say "much" to what I did 😀 I mean, I didn't change the whole digital power supply, for example, or even the trafo for a toroid, like some people do, etc... you can do much more mods... the question remaining then, is if it's worth the "trouble"... 😉

Phil:
What you said about OS and NOS, is a very concise resumée 🙂, I'd only add to it, that NOS also has its troubles, and they are not that small: the "stair-case" artifacts generated by the sampling frequency... yes, a normal analog active filter behind the I/V stage solves most severe problems, but leaves always a rest of "modulation", unless it's really complex multi-pole, but then you lose sound quality and phase linearity.
Anyway, not only high frequency loss is the consequence... not that you'd hear much of it, but well, it clearly is there... I can't say how tricky it is to get OS right, as I didn't do the mods sequencially in my player, but what I suppose is that you need a clock upgrade like I did, in order to have good OS sound, because it's more jitter sensitive. Probably I'd find NOS better sounding if I hadn't do the clock upgrade to my player... but like it is, suprisingly they really sound very similar... even the high frequency loss of NOS isn't very perceptible, probably due to the very nature of most music: it seldomly reaches out to over 15 khz... finally I do prefer OS also, if not only for the fact that while in A/B comparison sounding at least as good, I get a "theoretically" cleaner signal 😉

What I find strange though, is the difference of level: 1.86V for OS, and 2.09V for NOS?? 😕 I can't see how that happens... would be much better for comparing A/B if they had the same amplitude... maybe the 7220 reduces the amplitude while filtering in digital domain? Anyone knows that?

Sure that the I/V stage and filter do a lot to the sound... I wouldn't be suprised if a really well designed discrete I/V stage would outperform a standard opamp design... and even in opamp version, there is the choice between VFB (which I used) and CFB (some recommended it to me, others say it's worse... gotta try it one day!).

Regarding mods of the digital supplies, I haven't done anything there, except for better decoupling and exchanging all the caps for new ones. That would be something to try in the future: better regulator ICs (I have got to like one very special: the LT1963, it has ultra-low noise output...), seperate supplies, etc... one day when I have time 😉

About improving the servo section, don't think it's worth, at least with the CD40. Unless you mean doing it to avoid induction of digital noise to the rest of the circuit. Because the CD40, thanks to the CDM4, reads very well and quickly, almost every CD I through at it... much different than the old Technics (has a Sanyo laser unit) I have, it refuses to read some CDs, and I even had to do a complete readjustment to get it working acceptably again with normal CD-Rs (actually it's not that hard: find out where the Pot's are, mark there original position, put a good commercial CD in it, and start adjusting them, always looking to improvement of reading and tracking, etc... then repeat the process with a CD-R. Many a player that seems "laser dead" can be brought back to normal operation like this.)

Tibi:
can't answer your question. I am a little confused, though: what does OS mode have to do with error recovery? I thought that was done in a completely different IC (the 7310, if I'm not in error), so it should be exactly the same process, regardless of having the rest of the circuit in OS or NOS, no?😕
Click to expand...
i got your email.
but i think the +5V digital power supply is the most worthy to mods.my experience tells me the power supply for SAA7310 and SAA7220 are very important.
😀 😀
 
#23
Hi Joydivision,

I agree with Robo, and it reinforces what I was going to say which was that you don't have to go overboard with the regulators, for instance, for the 7220, a humble 7805 would be a good start.
I seperated out the supplies on my old CD63, using just 78xx regulators, and it such a huge difference.
Inductors on the power rails and decoupling capacitors can make a world of difference as well.
Cheers,
Phil
 
#27
joydivision said:
Indicate me your email adress and I'll send you the manual of CD50, which I've been using and which is almost 95% the same like CD40.

Btw, regarding the mods, in the meantime I've almost finished them, and the first results have been very good. I've a problem with NOS mode, though. As soon as I find the fault and get the whole thing finished, I'll post a complete report on here, for those who might be interested.
Click to expand...


Hi joydivision, I've got a Marantz CD60 and I think it's motherboard is basically the same as the 40 and 50. Could you send me a copy of the 40 schematic as I want to do a few things too. Thanks. 🙂
 
#29
🙂 Thanks very much joydivision for your gorgeous help. I am just getting it......by the way, I also have a Marantz CD-73 and have been looking for a schematic for a long time. Do you happen to know any sources? I like that machine but it has developed some constant digital noise on both channels and I would like to be able to bring it back.
 
#30
Yes, there are a couple of sites that have free service manuals, and also quite a few sites that have paid ones, but good quality and low prices. Some urls:

http://www.eserviceinfo.com/index.php?what=search2
http://www.free-service-manuals.com/
http://www.audiovideofoto.ro/index.php?option=com_remository&Itemid=63&func=select&id=88
http://www.manuals-in-pdf.com
http://www.justmanuals.com
http://www.zarekmanuals.com/

The problem you describe might be the DAC... I once had a Marantz (don't remember the model number now), and it always started to output white noise on one channel after maybe 30 mins of operation. Turned out the DAC was defective, don't know why... everytime you'd put for example a piece of metal on the chip - like a heatsink - the noise would go away for some time...
 
#31
joydivision said:
Hi ppl.

Just got myself a CD40 in great condition (with a nice TDA1541A in it), except for the tray loading gear wheel (like usually...). But cheap replacement part is already on its way (thanks, epos!). Now I'm in the process of modding the CDP. (yes, I do have the schematics) 😀
I want to replace the output stage (so to have a better opamp, not too much passive filtering, and no unnecessary components) and build a better regulated supply board for this.
I also started to "recap" the whole board (at least the 'lytics, as they are 16 years old by now...) and want to add a few decoupling caps or change them.
Of course, it'll get new gold plated RCA outputs aswell as some kind of metal shield around the boards of the output stage and it's PSU so to reduce HF interference from the digital circuits.
And last but not least, I will change it to NOS mode.
For now those are all the mods I plan to do. But I am open to every good suggestion, as long as it seems possible (and worthwhile) for me to realize them. I mean, I don't want to do overkill, you see... and I am no EE... lol

I've already done a little search on this forum and also on others, and found some good ideas, but still decided to open a new thread, because I couldn't find answers for everything. So, for a start, here comes the schematic of my planned output stage and it's PSU. I kept the same design as in the original schematic, simply excluding passive filters and unnecessary stuff (like the deemp. circuit). If you see any mistakes in it (hopefully not :rotfl: ) or anything that could be improved easily, please tell me 🙂

About the NOS, I found a little schematic explaining it, what they do is:

they connect WSAB, CLAB and DAAB directly to TDA1541. Now I am wondering if it's better to cut off the leads of the SAA7220, or to cut the traces on the PCB...
They also describe a Mute mod, so that without the muting transistors, one won't run into trouble with clicks and pops:
connect pin 23 (MUSB) of SAA7220 to pin 11 (MUTE) of SAA7210. The thing is, I have SAA7310 in my player... schematic says pin 18 is called MUTE (with trace over the word, as to say it's inverting). I suppose it'll work just like the SAA7210, no? Any experience with that?
Any other change recommended for NOS?
Read somewhere about changing the way the clock signal goes... but for now I don't want to build a new clock for it (would be the best, I suppose, but difficult to do), so I think the best is to leave things like they are, right?

In regards of replacing the 14 decoupling caps of TDA1541, is it worth to increase the size, to, let's say, 220nF?

Also, I was wondering if I should implement a simple RC lowpass filter in the last opamp stage... to filter out any rest of HF noise... keeping in mind that I want to do NOS mod... I know I can't get rid of harmonics (as that's the goal with the Digital Filter...), but that's ok... just thinking I'd like to avoid injecting HF noise to my amp 🙄


And finally, to simplify things for everyone, what I'm not going to do (too much hassle for too less a difference, and too much cost in a CDP that's not that good afterall...):

I am not going to replace the power supplies of the whole CD player (although I would do a few tweaks to them, if you have any suggestions. They are nothing fancy, but aren't bad either).
I am not going to make any physical alterations to the player (change the case, make it a top loader, change the transport's mounting, clamping or whatso on), because I think it's quite ok as it is...
And I am not going to do any "crazy" stuff like glueing hundreds of cork or whatever strange materials all over the player, or fitting any real "boutique" componentes, etc, I think you see what I mean 😉 .

Thanks in advance.

P.S.: if anyone needs the schematics, f.ex. of the PSU of the player, so to suggest mods, I'll post them here. I also can send the whole PDF per e-mail (it's of CD50, which is almost the same as CD40).
Click to expand...

I would be very happy to have a schematics of CD50 🙂
goran_bogoevski2000@yahoo.com
 
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