Plowman (News) wrote in message
...
I have a device where the crystal and associated network is external to
the CPU. Which isn't working. Looking across the two connections with a
scope there's no approx 30 kHz as should be - but what looks like very
dirty mains hum. Any way of easily testing the crystal other than by
substitution?

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*Why is the man who invests all your money called a broker? *

Dave Plowman London SW
To e-mail, change noise into sound.


Testing crystals,ceramic resonators and filters
Signal generator (RF) and scope. Connect the grounds together
and then connect the sig gen to the scope via the crystal.
Sweep the oscillator and resonant response at fundamental
and overtones will show on scope trace. Use a f counter
as well if f is required. If testing while
in circuit (unpowered) use less then 1V sig gen o/p .
The response may be muted comnpared to free component
especially for ceramic resonators.

from my tips files below

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Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/