Improving my old Marantz CD40?????

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Hey folks! I'm new to this forum so please bear with me, and my lack of experience.

I have an old Marantz CD40 CDP that works well but sounds quite "dull". I am interested in hot rodding it a little if possible.

I'd like some advice on what mods would be effective, and if this player is even worth playing with.

I have lots of experience with audio electronics, but very little with digital mods, so this is my "learning experience"

If the CDP doesn't make it, it won't be a loss for me.

Do a search for Cd upgrades... The Marantz cd40/50/60 and Philips CD610/620/630 all use the same/similar mother board with SAA7220 and tda1541. Clocks, caps, diodes, op amps.

I hot rodded a CD620 (identical to CD40 main pcb except has digital out) and it comfortably overtook a Rotel RCD965LE discrete with trichord clock. Mine only had a damped crystal.. The mods were op amps, diodes caps etc.
It just so happens that I've got a CD60 and did some research on it a while ago. The info that I gathered from other posts on this forum is shown below.

'thought I would make life easy for everyone and put it all in one place.

Also remember that the CD40 has the "R1" version ont TDA1541A - the lowest spec version. After you have exhausted all other mods - a final step might be to upgrade this chip to a standard A version.

Here are Jean-Paul's standard CD60 mods (from DiyA):

CD60 has a CDM4/19, plastic chassis and a completely different mainboard with an integrated power supply. I once modded a CD60 SE or KI that was flawed with some design errors that were not in the original one. Check which version you have.

It is a good cdplayer that much resembles the Philips types of those days. As with those Philips types I would decouple SAA7220 really well with 220 uF OSCON.

Replace output opamps with OP249 ( used that one at that time ), OP275 or better: wait for Rbroers output pcb's ! Output caps can be Nichicon MUSE ( leave them were they are or replace them for the same types ) or standard electrolytics which I would replace for a more audiophilic type. There is a member here ( Wkcheng I think ) that sells good bipolar electrolytics for audio. Please check if the output opamps have decoupling caps at all. In some Philips cdplayers with the same pcb they are omitted.

Decouple the servo opamps well. Replace all electrolytics with better types like Panasonic FC or BCComponents series 038. The original ones are worn out because of age. A Guido clock DIY with a separate transformer and supply will make the most difference but beware. The plastic case allows RF to leave the cdplayer in original state already and it'll be worse with a new clock. Better use metal screen against the "walls" of the plastic chassis with a connection to GND otherwise your radio and tv will notice when the cdplayer is on

A careful examination of ground routing is something for the experienced but it's worth the energy. Please disconnect the cables to the output with the potentiometer if you don't use the regulated output. You'll be surprised how much sound will be better. ( you cut approx. 25 cm of cable by doing so ). That counts for the headphone output as well. When doing so you can remove the headphone opamp IIRC. Use dampening/damping material like Bostik for the upper metal cover.

* watch out with touching the mainpcb of cd60. The copper is unprotected and it will corrode after is is touched * It is possible to coat it with polyurethane spray. I don 't feel for a discussion about the negative effects of that. It does have an influence though. Please cover *all* connectors and remove the cdm when spraying the board !!!!

These mods are more or less the standard approach of mine with the CDM oldies. There are more possibilities however like using an extra 7805 for SAA7220 alone or adding a new separate supply for the output stage.

I don't have a manual of this one but it is the standard Philips mainboard so you can use almost any manual you want of similar types.

Be careful with desoldering parts as the pcb tracks peel off easily. Better use desolder braid for that....

Comments from other members

Change all the rectifiers diode(with snubber network) to the fast recovery UG2B. Replaced some of the jumper wire with Ferrities bead for most of the supply lines.

Currently working on the ground looping. Detected that the SAA7310 is within the same loop as the servo amp(Motorola TCA0372 nd TDA8808/9 servo processor. I am now confused whether to group the TDA8808/9 and the SAA7310 in the same ground path cause they shared the same +5V regulator . But I am sure that the TDA8808/9 will be pretty noisy.

At the moment I settle for ground sharing of TDA8809/9 and TCA0372. The other ground will be shared by all others digital ICs.

Feeding the TCA0372 with it's own supply and ground is the best solution but it takes space which you don't have in that one. Personally I think it s too much work but it can be done in some of the oldies.

Feed the SAA7220 with it's own supply or decouple it with OSCON.

I need your advice on the ground looping. Is those grounding scheme that i applied is the correct way. I meant grouping the TCA0372 with the TDA8808/9 together and SAA7310/PCF3523P another separate group.

Some CD630 mods:

Well, started from +-15 v PS. Took of 7815/7915 and capacitors before and after. Diodes remain. Capacitors before regulator chanched to Elna Silmic 1000x35 - they are big, so one placed vertically in the same holes and another one lying on the bottom side of printed board (PB). After regulator Elna Starget 470x35 - both also on the bottom side of PB. Essentially regulator made on M5230L + transistors (Rohm) from datasheet. Placed also on the bottom side in the holes from 7815/7915. Capacitors from consume side (TDA1541 - 15V, LM833) changed to BG ST 100x16v. Resistors 10 ohm in-series remains. Capacitors of digital supply TDA1541 (+ - 5 v) changed to BG NX 220x6,3v. Digital power supply remains. O.K. Results: CD listening is YES "Magnification". Much & MUCH clearly, more opened and a new voices & instruments appeared !!! Sadly dislocate absence of deep , controlled bass. Without bas overall don't like this sound. Now will do digital PS on M5290 & clock. Will check. Heard that it's very hard to extract a deep bass from TDA1541A. What's your opinion?

The original capacitors are Nichicon 470x35 v and they are ~ three times smaller than Elna Silmic 1000x35, so I sad "big" just because of the can size ( 18 x 35,5, mm ) and yes, they are the biggest ones in can size that would fit, but not in the values. I just have them, so I used them. You can use any other capacitors even with the bigger values with ~ this sizes (Panasonic FC or FJ for example), but values bigger than 1500 mF would not be reasonable I think. I suggest you to put AFTER the regulator Black Gate's FK 470 mF (220 also will be O.K.) x 16 v and from the consume side also let's say 50-100 mF x16 v. They are making VERY good job. I'm already ordered FK and will change the presence ones for them.
Well now I have another issue...

I appears that my Marantz CD-40 is not the one that I though it was. It's a CD-40A which apparently is some kind of REALLY cheap player for those all-in-one systems. Inside it's all Sanyo. None of the stuff from the pics that I have found on this sight. It seems that I don't have much to work with here so I guess I'll dump it.

Can anyone reccomend a good used player to buy for some hot-rod expermentation???



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Hi Messerschmitt

what a strange place this BB is. I was given a CDP recently, and its a clone of yours. (You are right about the dull sound).

Mine is badged as a CDC 350CD, made by Chuo Denki. (about '89)

The main chips are Yamaha YM3805 and NJM2068.
I could not find anything on the Yamaha decoder, and the op amps are not considered very highly on this board.

The previous owner is no audiophile and of modest means, so I suspect Chuo Denky made these as OEM for whomever, then sold off the end of the run under the CDC badge.

There is one significant difference, the drive is completely different, the puck holder is hinged to the side (on the on/off relay arm) rather than over the tranny like yours. (Possibly a Sanyo drive)

Its rather well made, and the NJM2068 may have a lot to answer for.:cannotbe: so maybe good for modding

If the Yamaha decoder has any reputation that is.




Yes the same Chuo Denki that makes that super expensive belt drive transport....:cannotbe:
Well, at least I'm not the only one...

Well, at least I'm not the only one that own one of these!

Have you ever test driven a new car and decided: "this just doesn't feel right"? That's the same feeling I get when I think about modding this CDP.

There is possibility everywhere! Maybe even in this CDP, but I think I will pass. I'd like to start with an already decent CDP and learn to improve it. After all, my goal is to learn more about CD technology!

If you'd ike to play with this CDP let me know. It can be had for a song.

I would like some recomendations for some good players to modify for use!


A real CD40...........

Messerschmitt said:
I would like some recomendations for some good players to modify for use!

Why not start with what we originally thought you had - a real Marantz CD40/50/60 or a Philips CD630........?

One of these should be quite cheap, the schematics are available, they are well known by other modders/diyers, they have CDM4/19 (quite good), TDA1541A (very good), SAA7220 (so you can go oversampling or non-oversampling) - and a detailed list of mods is provided earlier in this thread (by me - of course).
Why not start with what we originally thought you had - a real Marantz CD40/50/60 or a Philips CD630........?

I'll second that.

I also have a real Marantz CD40, and would mod that in preference to the CDC, simply because its a known quantity, and the support this brings on this board. In the 'States they may masquerade under the Magnavox badge...

Yamaha YM3805 anyone?:rolleyes:


i'm sorry but my english it'is'nt good enough..
So, if i understood well, do you have service manuale of marantz Cd 40?
If so, thanks i advance if you could please email me.
I have an old one cdp, that have some problem with Cd's upload.
Could be the drawer, or some motor, DC supply... it's impossible to know for me, without schematic and design.

ash_dac said:

I could do with the schematic (need to examine psu).

I have the newer Marantz cd40, and plan to chuck a tda1543 dac in there from the I2S.

I picked the player up for £15 (about the price for five pints of beer).


Thank you very much, Ashley.
great informations!!!
I have the newer One ..:)
The first link it's good.
I don't understand deutsche, but...
best regards

ash_dac said:

Sorry I do not have the schematic :(

Which version of Marantz cd40 do you have ?

New type:-

Old type:-

Maybe try this ebay seller:-

Kind regards,

ash_dac said:

What does your cdplayer do when a cd is inserted?



Ciao Ashley,
at the first, my english is"dgrgorgnrogrp" , so sorry, ok?
When i put the cd in the drawer, and i push close, the drawer it's ok, but the cd, inside, jump out of right position, the clamper can't make anything, and cd don't rotate.
I think could be a mechanic problem, but could be a problem of supply, too, i don't know-
I'm looking for the sensor of drawer and other part, taht i don't know how could name in english.
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