Philips cd-471 mods - diyAudio
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Old 14th January 2011, 10:06 PM   #1
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Default Philips cd-471 mods

Hi,

I found a philips cd-471 at the thrift for silly money.
Always fun for some tweaking.
The player has a 4/19 mechanism and tda1541A dac.
I want to do this step by step.The player is not standard anymore.

Already changed:
* Psu diodes for BYV96-200
* Op-amps Opa2604/Opa2134/Ad826
* Psu caps Rubycon zl/panasonic fc
* muting transistors are removed
* 47 uf caps around the dac changed for Sanyo oscon
* Saa7220p/A changed for Saa7220p/B
* 4 caps panasonic fm by opamps
* Copper foil on the chips
* New psu with super reg for Saa7220p/B
* New psu with super reg for tda 1541A dac


The player sounds a lot better with these mods.
The last mod where the Sanyo oscon's and this was giant step forward.
I want to do more mods to this player. I found a couple of more mods:

* Changing output caps for mkp/mkt
* Decoupling the tda1541A dac with mkp/mkt
* Disable the headphone circuit
* Changing rca connectors
* New psu with super reg for a low jitter clock
* New psu with super reg for 7210
* Changing Oscon sp 47uf/16v for Oscon sepc polymer 220/470uf-16V
* Changing Panasonic FM 47uf/16v for Rubycon Zl/ZLH/ZLG 220/470uf-16v
* Damping the player with bitumen

Forgot something?
I'll take some pictures.

Last edited by Magura456; 31st January 2014 at 08:56 AM.
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Old 14th January 2011, 11:04 PM   #2
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Weird, it had the SAA7220A? Usually with TDA1541A I saw only the "7220B" versions...
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Old 15th January 2011, 12:37 PM   #3
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Probably the B version comes with the more exotic and top line players?
Anyway it's was difficult to put the chip in place with those tiny pins.
But the sound is better with the B chip.
Here 2 pics of the player (standard)
Attached Images
File Type: jpg P5020019.JPG (319.0 KB, 637 views)
File Type: jpg P5020026.JPG (491.9 KB, 579 views)

Last edited by Magura456; 15th January 2011 at 12:42 PM.
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Old 15th January 2011, 01:20 PM   #4
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Here some pictures with the mods.
Attached Images
File Type: jpg P1010018.JPG (898.4 KB, 585 views)
File Type: jpg P1010020.JPG (857.0 KB, 553 views)
File Type: jpg P1010021.JPG (895.4 KB, 532 views)
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Old 15th January 2011, 02:54 PM   #5
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I have a CD473, and I have rolled a few OpAmps too in it... I have stayed with LM4562.
But just plain TDA1541 chip in mine.
Attached Images
File Type: jpg crop1.JPG (349.1 KB, 285 views)
File Type: jpg crop2.JPG (311.7 KB, 187 views)
File Type: jpg crop3.jpg (402.8 KB, 202 views)
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Old 16th January 2011, 01:30 AM   #6
amc184 is offline amc184  New Zealand
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It sounds like you've covered the basic improvements pretty well, and the list you posted looks good, you're heading in the right direction. I have a few comments:

- Replacing the TDA1541A's many surface mount decoupling capacitors is worthwhile, they directly effect the sound, but not very dramatically. I recommend using polyphenylene sulphide (PPS) film capacitors, you can get these in 1206 and 1210 size package which will fit the PCB, much neater and more mechanically stable than tacking on leaded components. I've attach an image of this done on a TDA1541A based player.

- You didn't specifically mention it, but it sounds like you might be thinking of installing a low noise clock. That's definitely a good idea, it's one of the single biggest upgrades you can make to almost any player. It's best to get one with its own power supply (preferably including its own mains transformer), as half of the effect of a new clock is removing the power supply noise it makes so that it no longer effects the rest of the player.

- If you install copper foil over the ICs, don't forget to couple it to ground. I'd connect them to the ground plane through low value ceramic capacitors.

- Another thing to think about is damping. I don't have much of an opinion on it, but some players see improvement through damping their flimsy sheet metal cases.

- Yet another thing to think about is alternative output stages. There are lots of designs out there, using vacuum tubes and discrete solid state. It's a big modification, a lot of time and effort is involved, but the results are very good. I've tried a tube output stage, and I was pretty happy (see attached image).
Attached Images
File Type: jpg a.jpg (33.8 KB, 260 views)
File Type: jpg b.jpg (147.0 KB, 268 views)
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Old 16th January 2011, 02:56 PM   #7
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Quote:
Originally Posted by amc184 View Post
It sounds like you've covered the basic improvements pretty well, and the list you posted looks good, you're heading in the right direction. I have a few comments:

- Replacing the TDA1541A's many surface mount decoupling capacitors is worthwhile, they directly effect the sound, but not very dramatically. I recommend using polyphenylene sulphide (PPS) film capacitors, you can get these in 1206 and 1210 size package which will fit the PCB, much neater and more mechanically stable than tacking on leaded components. I've attach an image of this done on a TDA1541A based player.

- You didn't specifically mention it, but it sounds like you might be thinking of installing a low noise clock. That's definitely a good idea, it's one of the single biggest upgrades you can make to almost any player. It's best to get one with its own power supply (preferably including its own mains transformer), as half of the effect of a new clock is removing the power supply noise it makes so that it no longer effects the rest of the player.

- If you install copper foil over the ICs, don't forget to couple it to ground. I'd connect them to the ground plane through low value ceramic capacitors.

- Another thing to think about is damping. I don't have much of an opinion on it, but some players see improvement through damping their flimsy sheet metal cases.

- Yet another thing to think about is alternative output stages. There are lots of designs out there, using vacuum tubes and discrete solid state. It's a big modification, a lot of time and effort is involved, but the results are very good. I've tried a tube output stage, and I was pretty happy (see attached image).
Thanks for your input!

Ive got several wima mks caps for the tda decoupling, but they are to big.
The mainboard dont fit anymore, the caps touching the bottom case.
A solution is to saw a hole in the bottom at the place of the tda.
But these pps caps are a good replacement! What brand are they and sounds it better like wima,vishay, etc?

About the clock...i got also a shigaclone with a trichord clock 4 with psu (black gate caps). I can use this clock for a little test.

What value did you use for grounding the copper shield or isn't important?

I want to build several psu's (pre-regs) with super regs for feeding several chips like the saa7220p/b, tda1541A,saa7210,maybe the clock.
So i need the space in the player, because i want all the components in the player. It's probably imposable but i give it a try with several toroids (30va/50va).
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Old 16th January 2011, 03:22 PM   #8
poynton is offline poynton  United Kingdom
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Quote:
Originally Posted by amc184 View Post
........... I've tried a tube output stage, and I was pretty happy (see attached image).
As a matter of interest, what make are your tube buffers and where are they available ?


Andy


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Old 17th January 2011, 02:21 AM   #9
amc184 is offline amc184  New Zealand
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Quote:
But these pps caps are a good replacement! What brand are they and sounds it better like wima,vishay, etc?
PPS capacitors are really good, probably somewhere between MKT and MKP. They have both low leakage current, ESR, ESL and DF, so they're ideal for the application. Just keep an eye on the voltage rating. I used AVX made ones, but both Panasonic and Cornell Dubilier make them as well.

Quote:
What value did you use for grounding the copper shield or isn't important?
I don't think shielding the ICs is important at all, but just use whatever ceramic capacitors you have lying around.

Quote:
So i need the space in the player, because i want all the components in the player.
The CD471 isn't a crowded case, but it isn't exactly empty either. There is space above the mainboard, but I would hesitate to put a transformer there. Maybe think about making an external case. My favourite TDA1541A player (a Mission PCM II) uses an external clock, in a lot of players there's simply not enough space.

Quote:
As a matter of interest, what make are your tube buffers and where are they available ?
The tube buffers are my own design. I have a few PCBs and parts left over, PM me if you want to know more. I realised those photos are quite old, I've posted a more up to date image.
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File Type: jpg TTO.jpg (129.6 KB, 252 views)
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Old 25th January 2011, 03:08 PM   #10
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I need a little help please...

I want to put a new psu with the burson audio super reg.
Ive got a build psu from my shigaclone to test it and i want to feed the Saa7220p/B separately with the new psu.
But i don't exactly where to put 5v line into the saa7220p/B chip.
Can someone tell me where i have to look?

Thanks.
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