Rodrigo,
Just convert the 3 pin wall plug to a 2 pin wall plug.  (lift the ground
pin)
Believe it or not, you will be able to check almost any voltage then.  But
keep in mind that when you connect the ground of the probe to a circuit,
that the entire chassis of that scope will be at that potential.
Just a side note:
Be careful when using different wall plugs.  I have seen a situation that
one scope was plugged in on one wall, and we were measuring a circuit on
another wall.  The 2 walls were wired to different legs of the 220. (US wall
outlets are made up of 110 to ground of each leg of a 220 line)  Anyway,
with a simple wiring mistake in one outlet of neutral and ground getting
swapped (usually no problem)  when the probe touch the circuit, very big
sparks flew!!

Best regards,
Giles


>From: "Rodrigo Valladares P." <r-vallad@UNETE.CL>
>Reply-To: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
>To: PICLIST@MITVMA.MIT.EDU
>Subject: [PICLIST] [EE]: bad oscilloscope?
>Date: Wed, 13 Feb 2002 23:52:19 -0400
>
>Hi all,
>
>After reading the benefit of an oscilloscope, i took one that is not used
>in
>my work to debug (is this used in hardware too ?) a pic circuit. I have
>ZERO
>experience with scopes, so, and i attach the probe to Ch1, the probe has a
>clip, i grip it to gnd and the pin of the probe to what was i really want
>to
>measure... BUT, i have a 50Hz superimposed over my signal, and showme not
>really what i expect, then measuring the line ac make some spark in the
>probe (the scope can accept 400 vac). Using a tester, and the scope off, i
>discover that the clip is connected to the line ground (0 ohm), and i
>suppose that the test probe was isolated from the main line. I'm wrong and
>i
>must go to buy "measuring with a scope for newbies" or the scope is bad?, i
>don't have none to ask in my work, because is not used and is there only by
>a mistake
>
>The scope is a tektronix tds-310, and the probes (both with the same
>result)
>P6109B 10X
>
>( BTW, 50 Hz is the line frequency here )
>
>Thanks in advance
>
>RVP.
>
>--
>http://www.piclist.com hint: The PICList is archived three different
>ways.  See http://www.piclist.com/#archives for details.
>
>


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