Oscilloscope Audit Procedure
This procedure outlines the
steps in determining and documenting the current performance status of analog oscilloscopes. An oscilloscope probe with a 10X option is
required.
Plug the oscilloscope into AC
power and turn it on. It will typically
take several seconds for the oscilloscope to warm-up, which allow
the traces to be observed. The
oscilloscope, typically, has two channels.
Each channel will be tested. The
signal source for the test is the PROBE ADJUST output on the oscilloscope front
panel. This signal is a fixed square
wave output of approximately 1 kHz and 0.5 vpp. The probe might need adjustment for the
waveform to optimally appear as a square wave.
The adjustment is a small inset screw on the oscilloscope end of the
probe. But first, a display or trace is
required.
CH1 --
Locate the TRIGGER section of
the front panel. Assure that the TRIGGER
MODE is set to AUTO and the SOURCE selection is CH1. If a trace is not visible on the screen,
press the BEAM FIND button and a bright beam should appear on the screen. Whether the beam is on the upper or lower
half of the screen indicates how the trace CH1 vertical POSITION is adjusted
and how the CH1 vertical POSITION should be readjusted.
TRIGGER MODE settings
MODE – AUTO
SOURCE – CH1
HOLDOFF
– MIN if so equipped
VERTICLE MODE settings for CH1:
MODE – CH1
VOLTS/DIV – outer concentric knob at 0.1 volts for 10X
probe
inner concentric knob
(
COUPLING – AC
HORIZONTAL MODE settings for
CH1:
SEC/DIV – outer concentric knob at 0.2mS/div
inner concentric knob (
no DLY or MAG
Now, connect the probe to the
PROBE ADJUST signal on the front panel.
You should now see a square waveform displayed. If not, assure that the HOLDOFF is at
MIN. You may have to adjust the TRIGGER
LEVEL to see a steady waveform.
The vertical deflection
should be about 5 major divisions (0.5V) and the period should be about 5 major
divisions (1mS). Adjust the vertical and
horizontal position controls to optimize the waveform position for
measurement. Determine and document the waveform
vertical amplitude to a resolution of 0.01V.
Determine and document the waveform period to a resolution of 0.02mS.
CH2 –
Repeat the CH1 process for
CH2, replacing CH2 for every CH1 in the instructions. Document the results.