Modding a Marantz CD40

[joydivision]

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).

[robo]

Originally posted by joydivision
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?

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.

[philpoole]

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

[tubenut]

Yup, separate reg for noisy 7220 as I said beginning of this thread. Also agreed that even a humble 7805 is a mammoth improvement over the shared supplies.

[joydivision]

Well, your arguments are overwhelming
I promise the next time I open the cover of my CDP, I'll mess around with the power supplies

[riccardo]

]CDP Platform[/URL]

[jackx]

Originally posted by joydivision
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.

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.

[joydivision]

jack, as I've managed to find again the adress of the site from where I originally downloaded the manual, I post it here, so you can download it by yourself, and everyone else who passes by at this thread, too. I think the owner of the site won't mind, as this is fairly low-traffic

http://subaru2.univ-lemans.fr/~s031904/

[jackx]

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.

[joydivision]

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.p...c=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...