7
\$\begingroup\$

You bought your first entry level oscilloscope (e.g. Rigol DS1004Z series, 4 Channels, 50-100MHz, 1Gs/s) and while it is slowly warming up to room temperature you are wondering if the unit you have is really working well and did not suffer any damage from shipping etc.

Since your next complex measurement equipment is a multimeter, you wonder how to test it. Like, for a new computer you run memory test, hdd test, burn in tests (like mprime), so what is kind of an equivalent for oscilloscopes that can make you certain it is functioning mostly correctly?

Besides the built in square wave generator, what can you measure and check if it is properly displayed?

I am thinking of something like

  • A simple (breadboardable? though probably not at 100MHz) circuit that is almost guaranteed to work and can be used to check most things like bandwidth and accuracy of the scope.
  • A signal source that is rather easily accessible to most people and has quite known characteristics that when off tell you something is wrong.

Note: I am not asking about how to get familiar with the scope, but rather than some simple checks that assess it is functioning probably correctly.

\$\endgroup\$
  • \$\begingroup\$ Do you have a function generator? \$\endgroup\$ – Roger Rowland Mar 30 '15 at 10:59
  • \$\begingroup\$ @RogerRowland: No, "Since your next complex measurement equipment is a multimeter" ... nothing fancier than that. Think of a hobbyist starting with EE or so. \$\endgroup\$ – PlasmaHH Mar 30 '15 at 11:00
  • 3
    \$\begingroup\$ AndrejaKo is right : to accurately test it you need a fully equipped lab. However, for sanity checks : (1) a battery (2) the oscillator on an Arduino or Launchpad, or throw together a sketch to output a square wave. If all else fails, breadboard a 555. (3) if you have an AC mains transformer (say 12V), look at its secondary voltage and be appalled how non-sinusoidal the mains is... \$\endgroup\$ – Brian Drummond Mar 30 '15 at 11:36
  • \$\begingroup\$ Regarding doing a "burn-in" on a new computer, see superuser.com/questions/828722/… \$\endgroup\$ – Nit Mar 30 '15 at 14:21
11
\$\begingroup\$

If the square-wave looks fine after probe compensation and the scope passes self-check/self-calibration, then there really is nothing you can do at your level.

To properly check it, you'd need a good lab and you don't have that. Presumably, manufacturer would have performed quality control on the unit and did factory calibration with equipment much better than you have, so if you trust the manufacturer, you should be fine. If you don't, then, as I wrote previously, there is nothing you can do without proper equipment.

\$\endgroup\$
  • \$\begingroup\$ When I've bought new or refurbished oscilloscopes from Tek or Agilent, they come with a "certificate of calibration" that asserts the QA. When I've bought used scopes, it's up to me to verify against other equipment. \$\endgroup\$ – MarkU Mar 31 '15 at 1:46
5
\$\begingroup\$

Find a friend with an oscilloscope, and some circuits you can probe (these can be anything you have available).

Probe the circuits at various points with your new oscilloscope and the borrowed one, and check they see substantially the same thing. In most consumer devices, you will find a range of analogue and high frequency signals, just stay away from the mains power supply until you are competent to work in that area!

This does depend on temporary access to another oscilloscope, but is probably the simplest and most reliable method outside of having a full calibration laboratory. As a bonus, it will let you test your oscilloscope capabilities and give you confidence that you can use it correctly.

Any solutions which involve 'building a simple circuit' will always leave you wondering whether the circuit or the new oscilloscope is doing something unexpected.

\$\endgroup\$
3
\$\begingroup\$

Here's a list of more basic things you can check:

  • Check all the knobs (360 degrees in both turning directions) and buttons.
  • Compare readings at each voltage range to some reference, such as a multimeter. (If you hear a relay click at certain levels, you should test the range at each relay click.)
  • Test as many trigger types as you can. Compare the levels at which the scope triggers compared to where you set it, and compare the offsets for each direction.
  • Do all input tests for each channel.
  • Verify that the input of one channel does not affect any other more than it should. (Your manual probably specifies the minimum rejection ratio. At the very least, two channels of similar voltages shouldn't visibly impact one another.)
  • If your scope has additional functions like USB, Ethernet, SD card, etc, make sure to test these as well.

Obviously, these checks are far from perfect (you certainly won't be able to validate your scope this way, as AndrejaKo mentions), but this should help you find any glaring hardware faults. Just make sure you fully understand what you're seeing before you freak out about anything that seems off.

\$\endgroup\$
  • 3
    \$\begingroup\$ I'd add, open the manual to page 1 and work through all the features. Try everything once, at least everything you can. You might not be able to verify if the result is right, but at least you've now read the manual all the way through once.... ;-) \$\endgroup\$ – RBerteig Mar 30 '15 at 22:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.