What should I look for when purchasing a used oscilloscope?
I would recommend purchasing an oscilloscope made by a top-tier
manufacturer such as Tektronix or Agilent (formerly HP). These are
quality professional instruments which you should be able to get
easily serviced or purchase parts for.
Besides checking for the usual physical defects like rust,
cobwebs, a thriving insect colony take a look at the following --
- There is usually a calibration signal on the front
of the oscilloscope. For each channel --
- connect the calibration to the channel input
and adjust the voltage range selector.
- change the trigger source to the channel that
the signal is connected to. Adjust the trigger
level and verify that the oscilloscope triggers
when the level is set to value within the trigger
range. Also verify that the oscilloscope *does not*
trigger when the trigger level is outside the signal range.
- Change the voltage range selector knob and
verify the display is measuring the correct levels.
- Verify that the timebase function works.
- Oscilloscope probes are impedance matched to the input
of the oscilloscope. If the oscilloscope comes
with the proper probes this can save you a considerable amount
- Original manuals are useful but most manuals can
be downloaded form the manufacturer.