Thursday, March 31, 2011

Modding/Upgrading Marantz CD50 - part 4

Other mods to this player:
part 1
part 2
part 3
part 4 (this paper)
part 5

My final ideia for this player was a custom dedicated power supply regulators for the 2 most vital receiver chips - SAA7310 and SAA7220P/B.
I decided to use the upmarket version of 78xx regulator - LM2940CT-5, which is not so much noisy as the 78xx family and is easy to deploy on a PCB.

Here is the schema I used for the PSU regulators. One this I should notice is that you should use tantalum caps or premium grade ones, low ESR.
For the 2200uF I have got 2 x Elna Starget which are low ESR caps and good for audio.
1uF cap is Kemet tantalum - very fast capacitor! and with low ESR again
the 220uF caps are again Kemet tantalum but old stock in big corpus
and of course close to the chip we have 330uF Sanyo Oscon SEPC (this one is on the PCB of the player).

You might wonder why there is a 1R resistor in series. That was taken from the original Marantz design. It forms a Low Pass Filter with the Sanyo cap thus eliminating a low of the noise from the stock 7805 regulator at the cost of resistance.
That's okay in my opinion for this class of CD player. So I kept the resistors because the sound was better also checked by ears.

*) download power supply schema



Power regulators' board which will be installed in the cd player


Power regulators' board back


New power board installed (bottom view)




Stealing points for power line of the power reg board





Closer look to new power regulation board


Power connection for SAA7220P/B chip on 24 pin leg


Power connection for SAA7310 chip on 28 pin leg

And ... that's it! I am done with this marvellous cd player!
It has everything that can be upgraded and sings like a pure natural reality.

I hope these articles will be useful to someone and if you have questions please leave me a comment below.

2 comments:

  1. no comment but a BIG thank you :)

    ReplyDelete
  2. Thank you, too. I am glad that someone shared his opinion. :)

    ReplyDelete