overclocking SAA7220 ?

[Bernhard]

Hi,

what will happen when I replace the crystal with one that has double or triple frequency ?
Cook the chip ?

[Bernhard]

33.8688 MHz crystal in a Marantz CD273:

[Bernhard]

Why does it work ?

[Bernhard]

I moved the 33MHz crystal into a CD960 and measured - no change.

Maybe a 66MHz crystal will also work.

[JohnW]

Bernhard,

When you used the 33MHz crystal, did you measure the frequency? – I suspect that it is a 3rd overtone type – and in fact oscillates at somewhere near 11.2896 when connected to the 7220 XO circuit. I understand that the SAA7220 gets very hot at the best of times, and I cannot image it operating at 33.8688MHz! – not to mention serial clock speeds between other devices.

I would really not recommence operating the 7220 any faster than its rated Max Clock speed - most seem to have a great problem operating at 11MHz - and are very sensative to operating voltage - I remember once seeing a batch of Marantz CD players (CD65 I believe) that had to modify the VCC rail to allow the SAA7220 to operate...

John