Clock replacement

[nad]

Another question for any helpers out there......

Does anyone know if it is common practice when fitting any type/brand of ugraded clock to remove and jumper the 2 associated ceramic capacitors leading to earth from the old oscillators legs and also remove the parallel/series resistor?

Thank you

[Andrew Eckhardt]

The original capacitors are there as load specified for oscillation at the particular crystal frequency. If you are injecting a clock signal there is no need for these components anymore. If you are making your own oscillator you will need proper support components for your new crystal, specified by the manufacturer. Often these values will need trimmed for Exact operating frequency, and using the wrong ones will send you way out of the ballpark.

[nad]

Originally Posted by Andrew Eckhardt

The original capacitors are there as load specified for oscillation at the particular crystal frequency. If you are injecting a clock signal there is no need for these components anymore. If you are making your own oscillator you will need proper support components for your new crystal, specified by the manufacturer. Often these values will need trimmed for Exact operating frequency, and using the wrong ones will send you way out of the ballpark.

Thanks, great info. I'm fitting a diykits.com.hk clock and don't want to screw anything up. Do I remove the caps to ground and 'jumper' each of them (in point to out point on pcb) and just remove the resistor?


Thanks again
Ant

[Andrew Eckhardt]

I don't know what you're modifying. I can't even tell you which pin to tie the TCXO output to. You should have some info on the IC that you're externally clocking. The behavior (of a possibly disabled) internal oscillator will be described in the datasheet.

[nad]

Originally Posted by Andrew Eckhardt

I don't know what you're modifying. I can't even tell you which pin to tie the TCXO output to. You should have some info on the IC that you're externally clocking. The behavior (of a possibly disabled) internal oscillator will be described in the datasheet.

Sorry, its a NAD C515BEE and I didn't get anything with the clock apart from a simple schematic for populating the board.

Can't find anything on the old oscillator (WIN 16.934 MHZ (12PF)) either.

Thanks

[Andrew Eckhardt]

Originally Posted by nad

Sorry, its a NAD C515BEE and I didn't get anything with the clock apart from a simple schematic for populating the board.

Thanks

Do you have a schematic for your NAD unit or know the number of the IC you're feeding a new clock? Maybe someone on here knows about generic external clocking "protocol", but I can only help with manufacturers data.

[nad]

Originally Posted by Andrew Eckhardt

Do you have a schematic for your NAD unit or know the number of the IC you're feeding a new clock? Maybe someone on here knows about generic external clocking "protocol", but I can only help with manufacturers data.

Sorry, new to this diy, IC?

I dont have the schematic, although I'm desperately in need of it.

[Andrew Eckhardt]

Originally Posted by nad

Sorry, new to this diy, IC?

I dont have the schematic, although I'm desperately in need of it.

What is the part number on the chip you're adding the clock to?

[nad]

Originally Posted by Andrew Eckhardt

What is the part number on the chip you're adding the clock to?

Sorry for the delay...
It's a Toshiba TC94A54MFG 001 0725HBL 981968

[Andrew Eckhardt]

rats

That's an old IC. I can't get data on that, so I can't even tell you which pin is the input or output of the internal osc. You'll need someone that knows.