On 01/02/2011 09:58, alan.b.pearce@stfc.ac.uk wrote:
>>> That's a 32.768 kHz watch crystal.  No polarity, but somewhat
>>> vibration sensitive.  Still, it will probably work when you solder it
>>> back.
>>>
>>> Put a big glob of glue on it.  It's a bad design to have a part that
>>> big mounted without mechanical support.
>>>
>>> Regards,
>>> Mark
>> It's almost certainly a crystal.
>> The frequency could be almost anything up to 24MHz or so.  I have a
>> flash drive with a 12MHz crystal that's almost identical.
>>
>> In your case if you can't read the markings, you may be able to
>> measure the frequency using a simple oscillator circuit  and scope
>> etc. Or you could just solder it back in place and scope that or see
>> if it works. A dab of glue should stop it getting loose again.
> Yes, I agree, I doubt it is a 32kHz, more likely to be in the MHz range, =
to suit the USB connection, so 6, 8, 12 or 24MHz seem to be the favourites.

Me too, I'm 99.9% sure it's a crystal (tuning fork type IIRC) - I have a=20
few here of the 32.768kHz variety, just got a couple (of different part=20
numbers) out to look at - one case is completely blank, and the other=20
has 32 768 in tiny black numbers visible under a loupe.
I agree it's more likely a speed to suit the USB, though it's possible=20
it could be an RTC/Timer peripheral crystal if there is something else=20
on the board providing the USB clock.
I would go ahead and solder it back in (should be easy enough, just add=20
a bit of flux and you could probably do both pads at once, just tin the=20
tip of iron a little first, rather than adding solder to the joint -=20
like you would for drag soldering), think it's a pretty safe bet it will=20
be fine (though if you want to be extra cautious you could check it as=20
suggested)


--=20
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