[XCSSA] Oscilliscope help?

[X-otic Computer Systems of San Antonio]

On Mon, Mar 30, 2009 at 12:10 AM, X-otic Computer Systems of San
Antonio <xcssa at xcssa.org> wrote:
> On Sunday 29 March 2009 11:39:59 pm X-otic Computer Systems of San Antonio
> wrote:
>> I went ahead and got the Propeller dev kit and working with it has
>> been great so far, however I've come up on a problem.
>>
>> When I'm trying to read PWM signals with my oscilliscope, it shorts
>> out the chip and reboots it.  As a test, I used the usb to serial
>> "Propeller Key" adapter (which is essentially a USB to 3.3V serial
>> adapter)  as a test and kept transmitting while the oscilliscope was
>> attached to GND and the Tx pin.
>
> Hmm.. You using the probe's ground alligator clip to connect to the surface
> mount propeller board?  Just "clipping on" to the PCB is usually unstable at
> best.. at worst.. some times you'll short something out.. or even damage the
> traces on the board.  With thru-wire leads.. it easier to clip on.. but not
> so much with surface mount stuff.

It's not an "alligator clip" more like a micro-clip. (you push the end
like you would a syringe and then hook the coper hook end around what
you want to test).  This is on a breadboard and the ground lead is
connected to the same  ground as the rest of the board.  I've verified
this by even going back to the battery's negative terminal and still
have the same issue.

My test leads look a lot like  the ones in this link:

http://www.ece.rice.edu/%7Ejdw/figs/clip_leads.jpg


>
> What I recommend is actually soldering on a couple of "test point" wires.
> Solid wire for short term testing.  Stranded for longer term hookup points.
> One for GND and one for each test point.  The only example pic that I have is
> this one:
>
> http://theweeks.org/toms-stuff/2006-11_Alpha-Geek-Pics/2_Projects-old-and-new.jpg
>
> Examine the center photo of the Info-Globe hack.  Note how the red & green
> alligator clips are hooked up to the IR sniffer.
>
> Also.. might want to consider getting yourself some better hook-type test
> clips for hooking up to things.  Something with clip heads like this:
>        http://media.digikey.com/photos/3M Photos/923835-BU-C.jpg
> I think that Intertex has them.. but even Rat-Shack has them (in a pinch).
>


That link doesn't work, provides a "Error: System can't find the file"

>
>> No snickering... my oscilliscope is a Telequipment D61 and I used to
>> have the manual for it somewhere.
>
> Perfectly respectable 10MHz scope you have there.  You just have to make sure
> that you get someone to calibrate it for you every few years. :)
>

Well, I've probably had it for about 10 years and I seriously doubt
that the person that gave it to me had it calibrated.  What would I
need to calibrate it? I also have an older tube-driven scope that is
still fully functional and still works. :P

As always, thanks for the help, Tweeks!

FIRESTORM_v1