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Old 17th February 2004, 08:08 PM   #21
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Hi Jean-Paul,

I'll check the value of R25 when I get home from work and post the info here.

So the print for diode orientation on the power supply PCB is correct... Makes my problem even more puzzling.

I have no 5v present on the output pin of the LM317 putting the problem somewhere between the diode and the regulator.

Maybe there's a bad solder joint on one of the adjustment resistors for the LM317...??? Have to check that when I get home.

Can't see how a bad cap on the power rail would cause this symptom, but maybe there's a bad cap involved...??

Gonna be an expert at this machine soon.

Thanks for checking the diode print orientation
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Old 17th February 2004, 08:13 PM   #22
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TV man, you are making a small thinking error. The near 0 Volt at the output of LM317 can occur when too much current is drawn. A short circuit in the 5V line elsewhere in the cdplayer is a possibility. As you said the regulator gets instantly hot this might be the case

Just disconnect the DAC board and see if you've 5V again.
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Old 17th February 2004, 09:28 PM   #23
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Hi Jean-Paul,

Ran home for lunch and had a peek at the CD3...

R25 (near D7 & D10) is rated at 31 ohms by the color bands, although the orange band looks like it might be faded red. I measured it and got 27.5 ohms which would put it in spec for 31 ohms +- 10%.

Thanks for the correction on the regulator problem... I have measured without the D/A daughter card connected and still get .1v on the LM317 output pin. Maybe a short between the output pin and the power ribbon cable socket..?? Will check for this later as my lunch break is over

Back to work...
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Old 17th February 2004, 10:28 PM   #24
guido is offline guido  Netherlands
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Quote:
Originally posted by jean-paul


So I don't see a reason for *not* making this cdplayer non os. Chipset is identical to other normal Philips cdplayers. The 16 x Fs process is done after the SAA7220 on a separate board with shift registers.
So the registers are used to make 16*Fs, interesting. Now that you say it, it does ring a bell. I still think they are working on the i2s dataline, delaying samples. So at one point in time you have the current and previous samples available to load the tda's. And then adding up the outputs, which are then NOT outputting the same data (current). Current outputs connected together = currents added.

And i think the shift registers are loading the data coming from the 7220. When moving to non os in the normal way (remove 7220 and connect the shift registers to the 7210 output, it will not work imo.

The output of the 7220 is 16 bit words, the 7210 is 32 bit words. That is why the 7220 output has only double wordclock and not 4 times, as you would expect from 4 Fs. Because half of the bits from the 7210 contain no information, it's wordclock is two times higher than actually needed.

A DAC looks at the i2s ws signal and has no problem with the 16 or 32 bits. The shift registers will not. Instead of loading data, you loading dummy bits (zero?) You might end up with something like the digital decimation principle :->

Not having the schematics, i cannot be shure. But my gut feeling says it will not work without some changes to the logic.

More reverse engineering please !!!

Greetings,
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Old 17th February 2004, 11:40 PM   #25
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Hi Guido,

I've been thinking about the non os mod too... my impression is that it won't work with the shift registers, but would be easy to implement without them as a straight 4 DAC parallel non-os setup. The 4 DAC chips are on individual daughter cards attached to the D/A section PCB. Reworking the connections to bypass the shift registers should be a snap. But then I'm a junior propellor head stumped by a simple voltage regulator mishap so wtfdik
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Old 18th February 2004, 02:09 AM   #26
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OK think I found it. Looks like one of the small caps from the 5v line to ground is shorted.

It's one of the little brown ones marked with a 10 and 16v (not the orange .01) on the 5v line.

Will change and test again.

Thanks for your help and patience Jean-Paul
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Old 18th February 2004, 04:52 AM   #27
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Changed the bad cap. Now there's music

The CD3 had a slight harshness on some of the highs and mid-highs before the diode upgrade. Now most of that is gone. More smoothness with the 11DQ10 in place of 1N4004. Also better seperation of sounds in the same frequency range ie. vocal harmonies mixed with orchestral violins. The diode swap is a nice improvement.

The stock CD3 had a very rich tone. Now it's richer and smoother with better detail at the same time. No thin digital sound with this player!!

All the old electrolytic caps need to be replaced next

I drank a glass of wine this evening and meditated on my appreciation for this forum and the patient help from Jean-Paul that brought this round of improvements to my musical enjoyment.

Cheers to you and thanks

More tweaking to come, long live the CD3!!
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Old 18th February 2004, 07:01 AM   #28
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Congrats TV man. Please replace all tanatlum caps in the power supply as they fail often. They have a tendency of failing when used directly on supply rails.
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Old 18th February 2004, 04:30 PM   #29
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GuidoB, I don't see the problems you describe. I just see a standard chipset with the difference that there is a board added after the SAA7220 and that it drives 4 DAC boards.

So removing the SAA7220, 4 x TDA1541A and the 16 x Fs board will leave me a cdplayer with SAA7210 which can output directly to TDA1543. Could be that I am making a thinking error and not having a schematic does not help either but I don't foresee many problems that can't be overcome.
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Old 18th February 2004, 09:23 PM   #30
guido is offline guido  Netherlands
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Quote:
Originally posted by jean-paul
GuidoB, I don't see the problems you describe. I just see a standard chipset with the difference that there is a board added after the SAA7220 and that it drives 4 DAC boards.

So removing the SAA7220, 4 x TDA1541A and the 16 x Fs board will leave me a cdplayer with SAA7210 which can output directly to TDA1543. Could be that I am making a thinking error and not having a schematic does not help either but I don't foresee many problems that can't be overcome.
Jean-Paul,

You are absolutely right about that, i thought you were going to use the logic and 1541's with non os.

It's when you would put the logic and dacs after the 7210 there are problems (i think from the info i have now).

Guess there is enough space available when you have removed the pcb's.

Succes!
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