Tektronix TDS3000C Series User manual

Troubleshooting Your Design
with the TDS3000C Series Oscilloscopes

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Table of Contents
Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Debug Digital Timing Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Debug Rise Time and Fall Time Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Debug Threshold Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Debug Digital Logic Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Capture Elusive Glitches and Waveform Anomalies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 10
Check Signal Integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 12
Test For Presence of Video Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Test Each Line of a Video Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Determine if this Video Signal is the Desired Video Signal . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Check Video Color Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Check the Quality of a Communications Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 - 19
Make a Quick Pass/Fail Test of a Device-under-test (DUT) . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Look for Unintentional Circuit Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Remote Troubleshooting Using Your Computer’s Browser . . . . . . . . . . . . . . . . . . . . . . . . . . 22

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Getting Started
To optimize your measurements, it is important
to start at the beginning – by compensating
your probes and returning your oscilloscope to
a known state.
To compensate your probe, follow these
simple steps:
1. Connect the probe to channel 1.
2. Attach the probe tip and reference lead to the
Probe Comp connectors. If using the probe hook-tip,
ensure a proper connection by firmly twisting the tip
onto the probe.
3. Push Autoset.
4. Check the shape of the
displayed waveform to
determine if your probe
is compensated correctly.
5. If necessary, adjust your probe. Repeat as needed.
To return your oscilloscope to a known state,
follow these simple steps:
1. Press the front panel Save/Recall menu button.
2. Press the Recall Factory Setup bottom screen
menu button.
3. Press the OK Confirm Factory INIT side screen
menu button.
4. Press the front panel Autoset button.
Autoset
button
Probe
Comp
Channel 1
Adjusting Probe P6139A
Overcompensated
Undercompensated
Compensated Correctly

Debug Digital Timing Problems
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Digital designers need to quickly find and analyze a
wide range of circuit timing problems. For example,
race conditions and transients can cause circuits to
perform inaccurately. The TDS3000C Series’ pulse
width trigger can help troubleshoot such situations
by triggering when a signal pulse width is less than,
greater than, equal to or not equal to a specified
pulse width.
To use the pulse width trigger to capture a
glitch:
1. In the Trigger section, press the Menu button.
2. In the bottom menu, press Type until Pulse is selected.
3. In the bottom menu, press Class to select Width.
4. Select, as desired, Source, Polarity, Trigger When,
Level and Mode & Holdoff.

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Debug Rise Time and Fall Time Problems
Both analog and digital electronics designers
face problems related to slow edges (the rate of
change of volts over time), as measured by the
rise or fall time. The signal’s edge speed, known
as the slew rate, can affect the operation of
digital bus transceivers, transmission lines and
op-amp circuits. The TDS3000C Series’ slew
rate trigger can help troubleshoot such situations
by capturing waveforms where the slew rate is
less than, greater than, equal to, or not equal
to a specified rate. Automatic measurements
can supply supporting data.
To use the slew rate triggers:
1. In the Trigger section, press the Menu button.
2. In the bottom menu, press Type until Pulse is selected.
3. In the bottom menu, press Class to select Slew Rate.
4. Select, as desired, Source, Polarity, Trigger When,
Thresholds, and Mode & Holdoff.
To run automatic measurements:
1. Press the front panel Measurebutton.
2. Press the Select Measurement bottom menu button.
3. Select the desired measurements from the side menu.

Debug Threshold Problems
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Digital designers must quickly find and analyze
bus contention and other threshold problems.
The runt pulse trigger is useful to troubleshoot
such situations. A runt pulse is an illegal digital
signal that re-crosses a first threshold level before
crossing a second threshold level. A positive
runt pulse is a signal that first re-crosses the low
threshold level; a negative runt pulse is a signal
that first re-crosses the high threshold level.
To use the runt pulse triggers:
1. In the Trigger section, press the Menu button.
2. In the bottom menu, press Type until Pulse is selected.
3. In the bottom menu, press Class to select Runt.
4. Select, as desired, Source, Polarity, Trigger When,
Thresholds, and Mode & Holdoff.

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Debug Digital Logic Problems
Digital designers must troubleshoot logic condi-
tions on digital circuits. They may need to deter-
mine what happens when, or if, two signals meet
a Boolean trigger condition. They may want to
evaluate conditions when two signals become
logically true or false, such as from the output of
a two-input AND, OR, NAND, or NOR logic gate.
When troubleshooting digital logic synchronous
state machines, designers may want to determine
if a state signal is true or false at the time a clock
signal transition is true. The TDS3000C Series’
logic triggers, such as its pattern and state
triggers, can be used to tackle these problems.
To use these logic triggers:
1. In the Trigger section, press the Menu button.
2. In the bottom menu, press Type until Logic is selected.
3. In the bottom menu, press Class to select either
Pattern or State.
4. Select, as desired, Inputs, Trigger When, Thresholds,
and Mode & Holdoff.
5. For pattern triggers, also define whether to trigger on
AND, OR, NAND, or NOR conditions.

Capture Elusive Glitches and Waveform Anomalies
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In today’s high-speed digital designs, elusive glitches
and random anomalies can cause circuits to fail.
The TDS3000C Series speeds anomaly detection
with its digital phosphor technology and patented
WaveAlert waveform anomaly detection feature.
The TDS3000C Series employs digital phosphor
technology to capture and display infrequent wave-
forms or waveform variations. Its real-time intensity-
grading provides you with information about the
frequency of occurrence of signal amplitudes
and widths, making it easier to understand the
characteristics of the transients you’ve captured.
To fully utilize the TDS3000C Series’
digital phosphor technology:
1. Press the Display button to show the display menu.
2. Press Waveform Display on the bottom menu.
3. Confirm that Persist Time on the side menu is set to
Auto.
4. Press the Clear Persistence side menu button.
5. As desired, select the Backlight Intensity and
Graticule settings.
6. As desired, rotate the Waveform Intensity front
panel knob to adjust the persistence of the anomalous
waveform.

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Capture Elusive Glitches and Waveform Anomalies (continued)
The TDS3000C Series’ WaveAlert waveform anom-
aly detection feature speeds your troubleshooting
task by helping you find elusive problems faster.
WaveAlert monitors the incoming signals on all
channels and will detect and highlight any wave-
form that deviates from the “normal” waveform
being acquired. You have full control over how
sensitive WaveAlert is to changes, and you can
select from several actions for the oscilloscope to
take when it finds a problem – stop the acquisition,
sound a beep, print the problem waveform and/or
save the problem waveform to disk.
To use the WaveAlert waveform anomaly
detection feature:
1. Display the waveform on the screen.
2. Press the Acquirefront panel menu button.
3. Press the WaveAlert menu button.
4. Press the WFM Anomaly Detection side menu
button to select On.
5. Press the Highlight Anomalies button to select On.
6. Rotate the general-purpose knob to set the comparison
sensitivity value.
7. Use the Waveform Intensity front panel button to
adjust the persistence of the anomalous waveform.