how to troubleshoot?

[Jon Darby]

Howdy, everyone!
   Here's a question: I picked up an old tube Heathkit oscilloscope from an
R/C airplane convention in Pennsylvania a few years ago knowing I would need
one some day. Well, it seems to work wonderfully, but my eyes are 100%
untrained in in oscilloscopes, so is there a test procedure I can do to put
it through its paces and know it is functioning properly? Build a little
oscillator with known values and frequency maybe? How do you test an
oscilloscope in general? Is this a stupid question?

Your pal,
Jon

-----Original Message-----
From: patchell <patchell at silcom.com>
To: Linc at christeld.freeserve.co.uk <Linc at christeld.freeserve.co.uk>
Cc: Synth-Diy <synth-diy at node12b53.a2000.nl>
Date: Saturday, January 13, 2001 12:09 PM
Subject: Re: how to troubleshoot?


>    I have a digital scope at work, don't remember the model number, but a
>500MHz BW, 1GS/s Tek scope.  Real nice scope......BUT....aliasing can be a
real
>problem.  A good example is what I am doing right now.  I am trying to
track
>down an oscilation in a power amplifier that drives a three phase motor.
>Depending on how I set the sample rate, the display looks completely
>different.  The oscilation is about 1MHz and the signal that is supposed to
>come out is 500Hz.  The oscilation can look real funny, depending on how
close
>it happens to be to a ratio of the sample rate.  I generally have to turn
the
>sample rate knob (which also sets the equivalent to the sweep rate) in
order to
>make sure I get a "good idea" of what is really going on.  I have gone down
>many blind alleys because I failed to realize that the scope was lying to
me.
>Analog scope don't have this problem.  Still, as long as you know that the
>digital scope will lie, you can be careful.
>
>    Personally, my home scope is an analog.  It is only 20MHz bandwidth,
but
>that seems to be more than adequate for synth work.
>
>    -Jim
>
>Lincoln Fong wrote:
>
>> >>However if you got cash to spend get a digital so u can upload upload
the
>> results to the pc/mac(now were talking 1000$ range)
>>
>> I have always used analogue scopes and whilst talking about upgrading the
>> other day with a friend he mentioned that a good analogue is sometimes
>> better than a digital. I think it was something to do with the
quantisation
>> causing difficulty taking readings(?). Do you scope afficianados have a
>> preference? Its mainly for audio work which may have an influence. My
>> current one is 20MHz.
>> pc uploading is not necessary.
>>
>> Lincoln
>>
>> Ps without wanting to start another acronym bonanza what does AFAIK stand
>> for???
>
>--
> -Jim
>------------------------------------------------
>* Visit:http://www.silcom.com/~patchell/
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>*I'm sure glad Merry Christmas comes just once a year
>* -Yogi Yorgensen
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