Electronics > Beginners

Replace internal 10MHz crystal with external frequency standard?

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james_s:
The number is printed right on it, all I did was google LMX2582.

I'm not familiar with the particular frequency standard so I can't really say without knowing more. I'm sure it would be possible to do without too much effort but I don't think I'd be trying to modify an instrument like that unless there was a really good reason, there is always risk of damage and of course you will void the warranty and probably greatly reduce any resale value. What's wrong with the factory oscillator?

I don't mean this as an insult, but it seems like one of those tasks where if you have to ask how to do it, you probably don't need it.

radioactive:

--- Quote from: FriedMule on October 11, 2019, 08:43:01 pm ---[
Great way to guide me, I think I have found it:-)
It looks to mee as a passive crystal, right?

--- End quote ---

The LMX2582 has a differential reference input.  In the image you posted,  you can see one side of the differential input ac-coupled to a resistor tied to ground and the other side of the ref input being fed by the 10 MHz single-ended oscillator output.  At least that is what it looks like from the image.

FriedMule:

--- Quote from: radioactive on October 12, 2019, 04:42:50 am ---
--- Quote from: FriedMule on October 11, 2019, 08:43:01 pm ---[
Great way to guide me, I think I have found it:-)
It looks to mee as a passive crystal, right?

--- End quote ---

The LMX2582 has a differential reference input.  In the image you posted,  you can see one side of the differential input ac-coupled to a resistor tied to ground and the other side of the ref input being fed by the 10 MHz single-ended oscillator output.  At least that is what it looks like from the image.

--- End quote ---
Yes it is propperly how it is, but can first be sure after desoldering:-)

--- Quote from: james_s on October 12, 2019, 03:03:17 am ---The number is printed right on it, all I did was google LMX2582.

I'm not familiar with the particular frequency standard so I can't really say without knowing more. I'm sure it would be possible to do without too much effort but I don't think I'd be trying to modify an instrument like that unless there was a really good reason, there is always risk of damage and of course you will void the warranty and probably greatly reduce any resale value. What's wrong with the factory oscillator?

I don't mean this as an insult, but it seems like one of those tasks where if you have to ask how to do it, you probably don't need it.

--- End quote ---
LOL yes my comment was because I thought you had told the name on the crystal, but did wary fast find out that you meant the chip, but I kept the comment because it is still true:-)
The reason for me to replace the crystal is that it wanders all over the place and do in no way agree with my frequency standard. So I thought that why not get the scope to use the same standard as the rest of my gear and thereby let it all be in sync.

I had / do hope I could build a small circuit that could be "dumped" in the place where the crystal is now, without having to do much other then desolder the crystal and solder my contraption. :-)

EDIT: If I desolder the gray plate under the crystal, I think I can be less harch against the crystal and there are some space to use, maybe I could use some sort of soldi wire to act as "legs" pointing at the original soldering spots?

magic:
You will not desolder this 4-pad sub-PCB easily without a hot air gun. Maybe with ChipQuik.
And using hot air, you will melt the whole assembly and risk having it fall apart if you aren't careful.

You will greatly increase patient's chance of survival if you leave the generator alone and remove the coupling capacitor instead.

And really start with scoping the circuit to know what kind of voltage levels it uses and make sure you can generate a proper signal for it before taking anything apart.

Maybe see how it's done in the version with factory-made clock input.

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