Philips CD104 tweaks

[Elso Kwak]

Originally posted by JeroenR



Uhhh..... 1 is indeed 1000m.

Why do you ask.

Serious, I have no clue. I asked for 400mH because that is what I remember Guido reply once in a post. I got this one. (you can see it in the photo in my post on 20-2 in this thread, it is the small black dot in the middle) They told me it is 1H. As I do not have direct access to a decent parts-shop where I live I just used it. Next time I open the hood of the player I will check the label. My electronics experience is limited so I do not (yet) recognize silly values.

What would suggest as a good value?

Thanks,

Jeroen

Hi Jeroen, It could well be a Toko 1H coil but very limited in power handling. The max. current handling for these coils goes down with increasing inductance value:
5.6mH can handle 50 mA
100mH can handle only 9mA
1H I dunno but I think is clearly saturated.

In my clock I am using 2.2mH with no apparent advantage when using 47mH. Been there done that.

[JeroenR]

Originally posted by Elso Kwak

Hi Jeroen, It could well be a Toko 1H coil but very limited in power handling. The max. current handling for these coils goes down with increasing inductance value:
5.6mH can handle 50 mA
100mH can handle only 9mA
1H I dunno but I think is clearly saturated.

In my clock I am using 2.2mH with no apparent advantage when using 47mH. Been there done that.

Hi Elso, thanks for the warning. I will now definitely check the value.

[jives11]

I just noticed that there is a choke missing on my CD104.

5502 is shown as a choke providing the +5v supply to the SAA7030 yet on my CD104 it's actually a wire link ?

Interestingly the B&O CDX version of the doc shows it as link i.e reflecting the actual circuit board.

Wonder why they omited it, as I guess the OS filter polutes the +5v supply quite a bit ????? Cost of a 47uH choke is pretty small ?

[Co&]

Hi Jeroen e.a.,

Sorry for breaking in the chokethreads for boring you with the TDA1540, TDA1541 story.

*Why the more complicated route with the 1541? Is the 1540 that bad? Or was it just the chalange?*

The most important reason was that the 1540 dacs are 14 bits (technology was not ready for good 16 bit linearity). They are 'upsampled' by the digital filter to recover the original 16 bits. are 1541 series otoh are all genuine 16 bits stereo dacs....well that is if you take care of all the good advise by (former?) Philips designers and experienced DIYers (there is a lot of usefull info in this forum). If you take care of all the details I think modern dacs have a hard time keeping up (for the 16 bits).

Making the CD-104 NON-OS is a 'bit' tricky so to say, because ripping out the filter leaves you with two bits the 1540 DACS cannot handle . Maybe it works, they might just ignore the two LSBs (hopefully not the MSBs!).

Furthermore I allready had a SPDIF based TDA 1541A DAC running. Digging into the CD304 datasheets in search for the I2S interface I discovered that the TDA 1541 also has a mode that could support the output signals of the decoder (probably the 1541 was developed to also run with the established Philips decoder/filters). After rewiring the bunch it proved to work, actually a whole lot better than the SPDIF/I2S interface on the dac (also non-os).

The non-os 1541 is way better than the original with digital filter and 14bits dacs, but then again: I did no tweaking on the player.

Still the 1540 has somethings going for it: mono construction with dedicated decoupling on DAC and powersupplies, comparatively good sound (though a little coarse) and I believe that a lot of recordings don't even reach 12 bit resolution (especially the hot ones).

Sorry no pics yet. I totally lack craftmanship of any kind and am surprised that the bunch of wires and parts fires up and works!
Maybe later.

regards, Coen

[phofman]

Jeroen, take a loot at this thread

[rfbrw]

The SAA7030 does not recover 16 bits. It oversamples 16/44.1 to 14/176.4. DSP theory holds for each doubling of the sample rate, you can loose one bit and still retain the original performance. To quote Philips on the SAA7030,

It performs noise-shopping so that a 14-bit DAC yields the same in-band quantizing signal-to-noise ratio as from a 16-bit DAC supplied with unprocessed 44K1 samples.

The solution to using the TDA1540 without the SAA7030 in a CD player with the SAA70x0 chipset is to read the datasheet and put the SAA7000 into 14-bit mode.

[jives11]

Originally posted by jives11
I just noticed that there is a choke missing on my CD104.

5502 is shown as a choke providing the +5v supply to the SAA7030 yet on my CD104 it's actually a wire link ?

Interestingly the B&O CDX version of the doc shows it as link i.e reflecting the actual circuit board.

Wonder why they omited it, as I guess the OS filter polutes the +5v supply quite a bit ????? Cost of a 47uH choke is pretty small ?

I should have given the link to the schematic.
http://www.diyaudio.com/forums/attac...amp=1141413130

In this diagram there is a 47uH choke (5502) top left feeding the entire +5v supply to the digital filter (SAA7030) to pins 2,15,16,22,23,24. In my CD 104 it's a link. On every decoder board I have seen an image of ,in this forum and assorted japanese sites and Grundig CD7550 site - it's a link. Odd ?

[JeroenR]

Originally posted by Co&
Hi Jeroen e.a.,

Sorry for breaking in the chokethreads for boring you with the TDA1540, TDA1541 story.

....

Making the CD-104 NON-OS is a 'bit' tricky so to say, because ripping out the filter leaves you with two bits

.....

Sorry no pics yet. I totally lack craftmanship of any kind and am surprised that the bunch of wires and parts fires up and works!
Maybe later.

regards, Coen

It is not a chokethread and you are not boring me.

Any info regarding the 104/304/1540 etc is welcome...

Somewhere in this thread (or another) is described how to bypass the 7030 and put the 7000 in 14 bits; connect pint 16 to 5V via 1k. I will try this this weekend and let you know. And I will make a photo.

I'm still not happy after the clock went in. Did not bring the improvement I had hoped for. My girlfriend already asked me when we would start hearing the piano again, she is missing it...... I think I realy need a new I/V for this machine.

[JeroenR]

Originally posted by JeroenR



Hi Elso, thanks for the warning. I will now definitely check the value.

Hi Elso,

The shop confirmed the choke can handle about 200mA. The "about" in the answer made me doubt a bit though. They could not find the supplier... the item was too long on the shelve.

But here are some pictures, what do you think? Wires look thin...

Thanks,

Jeroen

[JeroenR]

And now top view.

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