Marantz CD50

[soulminer]

Hi Guys.

By any chance, does anyone have a schematic/circuit diagram and/or service manual with diagrams for a Marantz CD50. I believe it uses the same mainboard as a few other Marantz models that utilise the TDA1541A and SAA7220P/B, such as the CD40, CD60, CD65 and CD75. I think it may also share mainboards with some similar Philips players too. Maybe the CD-820, CD-880 or CD-960

I have just popped a couple of 8 pin DIL sockets in so I can do a spot of "op-amp rolling", but would dearly like to improve things such as replacing coupling caps, removing muting transistors, improving circuit components, etc, etc.

Thanks in anticipation,

[SimonC]

Hi Lee,

Take a trawl through the digital source section at www.diyaudio.com
There's loads of people on there who have useful info about Marantz CDP's. They have a big following on there amongst the CDP modders.

The link from Meno near the bottom of this still seems to be live:
http://www.diyaudio.com/forums/showt...=&pagenumber=2

Hope this is some use.

Simon C

[soulminer]

Wow !!! Brilliant !!! Managed to get the PDF from the guy's personal directory on the last link you provided. Many, many thanks Simon !! Now I can start "mod'ing" in earnest !!


Cheers.

PS: I had not even thought of looking on DIYAudio... It seems to be a good resource for stuff like this. I may spend a few hours browsing this site once again. Thanks for the pointer.

[soulminer]

For anyone that's interested, I purchased a used CD50 from a chap on eBay for the princely sum of £15. I have owned a fair few CD players in my days, including offerings from Naim, Arcam, Micromega, Tube Technolgy and Exposure to name but a few and was never really enamoured with any except maybe the TT. So, I decided to have a fiddle with one of these TDA1541 players to see if it was any good, and settled on the Marantz for cost and spares availability reasons.

On initial play, out of the box, so to speak, it was plainly quite dated, with that digital sheen to everything, but very easy to listen to and quite unremarkable really. Fairly detailed and I could have used it as was with no real complaints.

On acquiring the CD50 service manual last night (cheers again Simon), I decided to have a play. I have since turned this slightly drab and dated machine into possibly one of the best players I have heard to date, and it's only halfway modified too.

I have removed both NE5532N op-amps and fitted some 8 pin DIL sockets (high quality turned pin) to the main board. I have replaced the NE5532Ns with Texas Instruments NE5532Ps as that was all that Maplin had in stock (no shock there then!!) Hmmmm... maybe a slight improvement in detail and ambience with what seemed like a little more space around things. Not bad for total cost of £3.40, and it means I can do a little op-amp rolling now. I will get some OPAs and ADs to fiddle with soon.

I have fitted a small silicon damping ring (from a "Herbie's Halo") around the clock crystal can in lieu of a clock upgrade in the near future. This little mod also improved detail retrieval and seemed to improve focus too. Things seemed sharper and more defined in the sound stage. Not bad for a total cost of, errr... nothing!!

I carefully de soldered the SAA7220 decoder chip from the board, bent pins 1, 2 and 3, and 15, 16 and 18 up (for purposes of reversal) and then soldered it back in. I then soldered some little PTFE insulated silver links from pins 1 to 18, 2 to 16 and 3 to 15. This removes any filtering and oversampling which the SAA7220 had as standard (4x). I also broke the connection from pin 2 to pin 4 on the TDA1541A and connected pin 4 to ground (pin 5).The system is now non-oversampling (NOS). This was a superb modification for zero cost. The player is now in a different league. It has much more detail, but is also so much more natural and fluid. There are no hints of digital glare or artefacts any more and the space and ambience around players in performances is superb. I would go as far to say that it is now approaching an almost analogue sound.

I have also removed the muting transistors and resistors from the output circuit by connecting the output of the op-amps directly to the phono sockets on the chassis. I have even ditched the blocking caps. This had the effect of improving the treble and detail again slightly. The amount of detail this thing is pulling out is now really good. I am hearing nuances in recordings I know well, for the first time, but it is never too much. It is still extremely musical and non-fatiguing.

All of the transport has been removed, cleaned and re-greased with Teflon grease, and any ancillary item removed from the player, such as variable output control boards, headphone sockets, etc.

So total cost of all mods so far... £3.40 and £15 for the player itself. Hmmmm... not bad. Next up is to order 10 Schottkys for all the PS rectifiers and some decent caps (BG, Elna, Sanyo) for the PS smoothing. Some op-amps for rolling (of which the AD826 is meant to be the best) and some Dynamat for chassis and transport damping. This lot should come in under the £50 - £75 mark leaving a new system clock to be purchased some time in the future. I reckon this player with all the aforementioned mods should easily outperform some players I have owned that cost in excess of £2k, and it will have cost me in the region of £100 and a few hours tinkering. Most importantly though, it is so easy and satisfying to do, and as with any DIY/modification, gives one a massive sense of achievement.

Long live the TDA1541A and CDM 9/14 combo !!

Cheers,

[Audiognome]

Hi Lee,

I'm very interested in what you're doing! I'm also playing with CD players, although I haven't been quite as brave as you, yet (the lack of a schematic isn't helping, in my case).
With regard to the op-amps, I've found that changing the "cooking" op-amps to LM4562 was a worthwhile improvement. Unfortunately I don't have any spare, but I do have a couple of OPA2604, if you'd like to give them a go. Surface mount package only, I'm afraid, but you could always solder them across another socket and plug that into the sockets you've fitted on the board. PM me if interested.
Now, I must go and update my thread as well ...

Nigel.

[soulminer]

Hi Nigel.

Many thanks for the offer, but about a day too late I'm afraid. I ordered some from RS last night in DIL package along with some OPA2134 and AD826ANs. I will have a play when they arrive and time permits.

Performing the NOS mod on the SAA7220 and removing the muting transistors brings its own problems in the form of pops and clicks when idle and also track noise whilst "next-ing" or "previous-ing" or pausing. The answer here is to connect pin 23 (MUSB) of the SAA7220 to pin 18 (MUTE) of the SAA7310. This restores the player to its previous set-up, but mutes the player in the decoder rather than discretely using the transistors. Nice little mod. Just done it now.

Cheers,