Philips cd-471 mods

[Magura456]

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 gone
* 47 uf caps around the dac changed for Sanyo oscon
* Saa7220p/A changed for Saa7220p/B
* 4 caps panasonic fc by opamps

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 Saa7220p/B
* New psu with super reg for tda dac
* New psu with super reg for a clock
* New psu with super reg for 7210
* Copper foil on the chips

Forgot something???
Is it difficult to integrate the new psu with the regs on the 7220 and the dac?
I'll take some pictures.

[SoNic_real_one]

Weird, it had the SAA7220A? Usually with TDA1541A I saw only the "7220B" versions...

[Magura456]

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)

[Magura456]

Here some pictures with the mods.

[SoNic_real_one]

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.

[amc184]

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).

[Magura456]

Originally Posted by amc184

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!

I´ve got several wima mks caps for the tda decoupling, but they are to big.
The mainboard don´t 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).

[poynton]

Originally Posted by amc184

........... 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


.

[amc184]

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.

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.

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.

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.

[Magura456]

I need a little help please...

I want to put a new psu with the burson audio super reg.
I´ve 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.