Marantz CD63 & CD67 mods list

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RCruz

RCruz

Member
Joined 2006
Paid Member
RCruz said:

In the CD53, I see the 120pF C601/602 caps are in parallel with the feedback resistors R603/604.
Click to expand...

After some "googling" I found the answer:

The 120pF bypassing the 27k resistor creates a roloff freq of 49121Hz acording to the formulae: C = 1 / (2 * pi * R * f)

Maybe this intended to prevent the opamp from oscilating, or to simply reduce high freq noise at the output.

Using a better opamp, maybe we could reduce C601/602 value ?

Ricardo
 
Malefoda

Malefoda

Member
Joined 2006
rx7france.com
UV101 said:



This is true if you are talking about "pluging in" to 8dil sockets.

I've currently got this DOS running in my philips CD960 which is a TDA1541 player. The only change required to get it working was to ground the inverting input for each channel.

TBH if you're starting to make changes in this area, you can obvioulsy use a soldering iron so i don't see why this ability to easily plug in and out is an argument.

The DOS in std form is a much better sounding circuit than the Bursons. It will replace the entire output stage of the player. Unless you make all the mods to the filter and outputstage (on Rays list pg1) and even then, you will always be at a disadvantage running the Burson's.

I'd personally recommend the DOS over the Bursons.

Ian
Click to expand...

What does DOS stand for?

The 960 looks ugly but is a great player... great DAC!
I think this usefull wbesite is already in your bookmarks guys:
http://lampizator.eu/LAMPIZATOR/REFERENCES/references.html

Matthieu
 
RCruz

RCruz

Member
Joined 2006
Paid Member
rowemeister said:

Ricardo you have a good ear so you need to try this and it only takes 5 mins to test.

RD14 / C521 near dac (same part) cut a leg.
Run short wire from dac clock output to decoder side of U193 near decoder (actually fitted with a resistor)

On the test one here the detail jumped out, the music became much smoother and fluid.
Click to expand...
Hi Brent

Do you mean you keep RD14, but wire it directly to the decoder CRIN (Pin13) ?

After having been dedicated to the Riaa, I feel the CDP needs some care in the high freq area :D

Thanks Lee

Ricardo
 
Thomo

Thomo

Member
Joined 2006
Looking at the board, I think you should lift one leg of rd14 to take it out of circuit.

Also lift the one side of U193 to do the same, and then feed clock input directly into the Decoder Pin 13.

Cheers, Lee.

Edit: you can just snip the legs, no need to even remove the board. Very handy and free mod - which is nice.

Lee.
 
RCruz

RCruz

Member
Joined 2006
Paid Member
Lifted the lid.....:smash:

It does not look very easy... instead of a resistor I have a cap in RD14 place.

Can not see the link... maybe under the decoder psu pcb ?!
 

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poynton

poynton

Member
Joined 2005
RCruz said:


After some "googling" I found the answer:

The 120pF bypassing the 27k resistor creates a roloff freq of 49121Hz acording to the formulae: C = 1 / (2 * pi * R * f)

Maybe this intended to prevent the opamp from oscilating, or to simply reduce high freq noise at the output.

Using a better opamp, maybe we could reduce C601/602 value ?

Ricardo
Click to expand...

Why????


It rolls off at above 44.1kHz reducing alias products


Andy
 
RCruz

RCruz

Member
Joined 2006
Paid Member
poynton said:


Why????


It rolls off at above 44.1kHz reducing alias products
Click to expand...
Thank you so much Andy

Now I am sure about those caps.

I have cpas bypassing the feedback resistor in the inverting voltage opamp in the 101b output and was wondering if I could change them.

It seems they are there just to limit the preamp bandwith and reduce noise.

Regards

Ricardo
 
P

padman

Member
Joined 2008
Hey all, Rekon you must be getting bored of my babbling but i'm so pleased with the results so far:D

I'm all out of parts now, well except the x7r cap as per acoustica inveterate meddling but i'm not ready for that just yet!!

Just seperated supplies and the player still works:D :D

Might pull the board 1 more time to remove HDAM completely R651 to 654 if i read correctly

Work so far
opamps and caps, HDAM bypass, shottkeys, PSU caps, seperated supplies to dac, headphone disconnected and sound ded plus footwear....... Thats it!!

The player sounds fantastic compared to original i'm amazed a £35 player and £50 parts a lot of reading and advise off you guys can change so dramatically :D :D

Thanks again guys Ian
 
S

stueyh

Member
Joined 2004
Seem to have hit a bit of a snag!

Fiited two 5v regs today (just LM-based ones). I checked the regs before and they were reading 5.01V so I thought that was close enough! Anyway, put everything back, powered up nothing apart from the CD slowly going backwards and forwards as if someone was trying some scratching.

Switched off, fiddled, switched back on and everything was back as normal.......for about 10 minutes then it just went, no power. The seperate PSU for the clock is working and thats installed after the switch so I can rule that out. I've readings anywhere on the board. The fuses are intact.

Anybody any ideas??
 
Fidelity Audio

Fidelity Audio

Member
Joined 2005
fidelityaudio.co.uk
stueyh said:
Seem to have hit a bit of a snag!

Fiited two 5v regs today (just LM-based ones). I checked the regs before and they were reading 5.01V so I thought that was close enough! Anyway, put everything back, powered up nothing apart from the CD slowly going backwards and forwards as if someone was trying some scratching.

Switched off, fiddled, switched back on and everything was back as normal.......for about 10 minutes then it just went, no power. The seperate PSU for the clock is working and thats installed after the switch so I can rule that out. I've readings anywhere on the board. The fuses are intact.

Anybody any ideas??
Click to expand...

Is the clock psu gnd to the cdp gnd?

After the regs do you have any smoothing caps?

Brent
 
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