how to safely take measurements with oscilloscope??

[c4757p]

By the way, even if you did put your ground clip on a dead short, you're unlikely to blow your scope. The ground connection from the front-panel connectors goes straight through the massive bulk of the chassis (or the slightly thinner shielding metal of a newer digital scope) to the earth pin on the mains connector. You'd need a hell of a power supply to blow that up. You're more likely to damage your probe, or even more likely the circuit you're testing, which is less of a loss than an oscilloscope.

[kasumyku]

@ c4757p    that was pretty much my main concern, just bought my first brand new scope so I didn't want from my first few testings to blow it up, that will be a drawback...but as every experienced electronics guy says " I hope you will fail the first time..." so we can all learn from mistakes 

[ddavidebor]

Checking the test points with a multimeter before attaching a scope is an excellent practice. Even more so if the DUT is plugged into mains. Checking the voltage between the bnc jack on your scope and the point on your circuit you are about to hook the scope ground to can prevent a nasty surprise.

Well, a multimeter is not necessary.

Just try to measure with your scope without the ground clip.

Since the scope is ground referenced, you'll find voltages between ground and a ground referenced path.

[IanB]

Checking the test points with a multimeter before attaching a scope is an excellent practice. Even more so if the DUT is plugged into mains. Checking the voltage between the bnc jack on your scope and the point on your circuit you are about to hook the scope ground to can prevent a nasty surprise.

Well, a multimeter is not necessary.

Just try to measure with your scope without the ground clip.

Since the scope is ground referenced, you'll find voltages between ground and a ground referenced path.

That's not the point. You do not want to find any high voltages with your scope probe since the scope input cannot necessarily handle them. You want to find the high voltages with your multimeter so you can avoid probing them with your scope and protect your expensive scope from harm.

[ddavidebor]

well, you MUST know that order of magnitude is the voltage in your board.

it's 3v battery? 30v power supply from transformer? 300v bridge rectifier? 3000v hight tensione crt? or a 15000 ones?

next, just probe with 10x and live happy

[vk6zgo]

@ c4757p    that was pretty much my main concern, just bought my first brand new scope so I didn't want from my first few testings to blow it up, that will be a drawback...but as every experienced electronics guy says " I hope you will fail the first time..." so we can all learn from mistakes 

I've never subscribed to that idea,you don't learn Electronics theory by just diving in like a "Bull in a China shop".
What you will learn from things that don't work is to pay more attention to theory & think things through before leaping in.

Learn from other people's mistakes & listen to what experienced people say.
Some err on the side af too much caution,others are too "laid back",& most are somewhere in the middle.

[G7PSK]

I have just come across this book today, ordered a copy to have a look as it appears interesting the seller still has another copy. Might be cheaper elsewhere but I was not about to bother looking.

http://www.ebay.co.uk/itm/150955438475?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

[alm]

Reading the Tektronix appnotes "XYZs of Oscilloscopes" and "ABCs of probes" would also be informative and is free. Note that there are several versions, the old ones focussed on analog scopes and the more recent versions (eg. the one you can find on their website) are about modern digital scopes.

[fpliuzzi]

In addition to the two excellent appnotes alm mentioned, here's another Tektronix appnote that may be of interest. The attached PDF file is "Fundamentals of Floating Measurements and Isolated Input Oscilloscopes".

Regards,
Frank