Probably easy clock question

[Tor M]

Hi!

I have bought a seconhand Philips player, and I`m going to go non oversampling.

So my question is:

When I remove the saa7220 digital filter I have to feed the clock (Tent clock) directly to the clock input at the saa7310 decoder. Do I then have to add a resitstor (200K- 1M) between the the clock input and the clock output on the 7310? Or is this resistor only needed when it is fed by a passive crystal?

Thanks

Tor Martin

[jean-paul]

Please leave the resistor where it is or you'll experience weird behaviour of your cdplayer !!! Remove only the crystal and the 2 small capacitors.

edit: I misunderstood your question probably. When there isn't a resistor in the datasheet/typical application of SAA7310 you don't need one. It's too late now to check.

[Tor M]

Hi!

Thanks for answering, Jean Paul!

Sorry, my question may have been a bit "unclear".

The player is a cd 820, and it uses the same mainboard as cd 620, marantz cd40.......

The 7310 gets it`s clock signal from the "xsys" pin on the 7220 without having a resistor between it`s "X-in" pin and it`s "X-out" pin.

The 7220 have the standard 220k resistor in paralell with the crystal, between x-in and x-out.

So I thought this was easy, after I remove the 7220, I just feed the x-in pin of the 7310 with a tent clock, the same way is was fed before. But then I found this page where they add the resistor: http://xoomer.virgilio.it/hi_fi/jitt.htm

Hopefully this is not needed, because it would go between pin 25 and 26 on the smd version of the 7310, and I would rather avoid soldering anything between thoose small pins.

Thanks

Tor M

[Guido Tent]

Originally posted by Tor M
Hi!

Thanks for answering, Jean Paul!

Sorry, my question may have been a bit "unclear".

The player is a cd 820, and it uses the same mainboard as cd 620, marantz cd40.......

The 7310 gets it`s clock signal from the "xsys" pin on the 7220 without having a resistor between it`s "X-in" pin and it`s "X-out" pin.

The 7220 have the standard 220k resistor in paralell with the crystal, between x-in and x-out.

So I thought this was easy, after I remove the 7220, I just feed the x-in pin of the 7310 with a tent clock, the same way is was fed before. But then I found this page where they add the resistor: http://xoomer.virgilio.it/hi_fi/jitt.htm

Hopefully this is not needed, because it would go between pin 25 and 26 on the smd version of the 7310, and I would rather avoid soldering anything between thoose small pins.

Thanks

Tor M

Hi Tor,

This way you do not need the resitor. The resistor is often present to make sure the crystal oscillator is correctly biased

succes

[jean-paul]

In some cdplayers I noticed weird behaviour when the original crystal and parallel resistor were removed. I think Marantz CD 38 or 36 was one of them.

[peranders]

Weird in what way? This resistor is only feedback so the crystal can start oscillating. If you feed a good signal into the inverter input, I can't see how this resistor could do something positive, but on the other, it's not harmful either, or...?

[jean-paul]

Spindle motor spinning very fast and/or skipping ( behaviour like disconnected clock ). The internal ports locked like a comparator without the resistor. Modern chipsets have the resistor often built in as you can see in their datasheets. I know its supposed to be used with crystals.

After having experienced this phenomenon I leave the 220 K to 1 M resistor where it is as it does not do harm.

Please note that I am talking about older generations of Philips chipsets here.

[Tor M]

Hi!

Thanks for answering!

I`ll feed the 7310 without the resistor, and if it starts acting weird I know where to add it.

Thanks

Tor Martin

[carlosfm]

Tor, I don't know that player, but check it out if removing the 7220 you don't loose the S/PDIF output.
If you won't ever need it, fine.

[Fin]

I am installing a Tent Clock (XO2) in a Philips CD624. The original arrangement has the crystal connected to the SAA7321 Bitstream DAC (with built in filter).

The standard installation involves removal of the crystal and accompanying 2 capacitors and then connecting the new colck module to the points vacated by the crystal.

Is this the best implementation?
Should I also make a connection from the clock module directly to the SAA7310 decoder?
If so - should I cut the clock trace between the SAA7310 and SAA7321?