P14345 Hardware Test Procedure
1 Introduction
The scope of this document is to outline the procedures used in testing, verification,
and validation of the Hybrid Audio Dynamics Processor. This document will provide
guides and methods used in testing. Users should continue to update the document
as portions are tested and the systems are analyzed.
2 Hardware Sub-System Testing
2.1 Input Section Testing
This test confirms that the difference amp is functioning as designed.
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Populate all components in the input section, except for the 0 Ohm jumper on
the output.
Check for shorts between power and ground.
Generate a 1VPP 1kHz sine wave using the function generator and apply it to
the Channel 1 non-inverting input. Use an oscilloscope to compare the input
to the output, they should be identical.
Generate a 1VPP 1kHz sine wave using the function generator and apply it to
the Channel 1 inverting input. Use an oscilloscope to compare the input to
the output, they should be phase shifted 180 degrees.
Generate a 1VPP 1kHz sine wave and use the balancing test board to create
the single sided signal into a differential signal. The differential signals
should measure 1VPP each. Apply those signals to the Channel 1 inverting and
non-inverting inputs. Measure the output, it should be 2 VPP.
Repeat for Channel 2.
2.2 Precision Rectifier Testing
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Populate all components in the precision rectifier section, except for the 0
Ohm jumper on the output.
Check for shorts between power and ground.
Generate a 1VPP 1kHz sine wave using the function generator and apply it to
CH1_RECT_IN.
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Use an oscilloscope to compare input vs. the output. The output should be a
rectified copy of the input. Observe rectified zero crossing incidents for
distortion.
Repeat for CH2_RECT_IN.
2.3 Low Pass Filter Testing
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Populate all components in the LPF section, except for the 0 Ohm jumper on
the output.
Check for shorts between power and ground.
Setup up the oscilloscope to perform an FFT.
Connect Oscilloscope Channel 1 to LPF_IN_1 and Channel 2 to LPF_OUT_1,
perform the FFT.
Compare the frequency response of the filter against the design parameters.
Repeat the same procedure for LFP_IN_2 and LPF_OUT_2.
2.4 Output Stage Testing
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Populate all components in the output stage testing.
Check for shorts between power and ground.
Generate a 1VPP 1kHz sine wave using the function generator and apply it to
CH1_LN_DVR_IN.
With an Oscilloscope, observe the input and the +_OUT, they should be
identical.
With an Oscilloscope, observe the input and the -_OUT, they should be 180
degrees out of phase.
Repeat with CH2_LN_DVR_IN.
2.5 VCA Section Testing
There are multiple tests for the section and they are a little more involved than the
previous sections. The first test is to confirm the build is correct and that control
voltages are correct.
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Populate all components in the VCA section, except for the 0 Ohm jumper on
the output AND the VCAs AND R108-R111.
Check for shorts between power and ground.
Populate R47-R49 in the MCU section.
Generate a 1VPP 1kHz sine wave using the function generator and apply it to
U11.29 & U11.30
Check the voltages at R109 and R111, it should be 0.045VPP
Turn RV1 and RV2 until the voltage at U4.4 & U4.5 is 0.1V +/- 0.05V.
The next test to confirm that the gain constant is -6.1mv/dB.
 Populate U4, R108, and R109.
 Check for shorts between power and ground.
 Apply 400mV to U11.29 & U11.30.
 Generate a 1VPP 1kHz sine wave using the function generator and apply it to
CH1_VCA_IN. Measure CH1_VCA_OUT against CH1_VCA_IN, there should be
3dB of gain reduction.
2.6 MCU Testing
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Populate all components in the MCU section.
Check for shorts between power and ground.
Load code.
Perform Software Testing to verify hardware
3 Hardware Performance Testing
3.1 Common Mode Rejection Testing
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Generate a 10VPP 1kHz sine wave using the function generator and apply it to
CH1- and CH1+. Using the oscilloscope and measure the input vs. the output
at the test point. Using the math function of the oscilloscope, display dB. The
magnitude of CMR should be greater that 50dB.
3.2 Bandwidth Testing
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Hook the output of the network analyzer to inputs CH1-/+.
Hook the inputs of the network analyzer to the output CH1-/+.
Perform a frequency sweep from 1Hz-200kHz and obtain the Bode plot.
Compare that data against design requirement. Target range is 20Hz –
20kHz.
3.3 Noise Testing
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Configure a precision op-amp with a gain of 100.
With the system not in bypass and no make-up gain, hook channel one output
to the precision op-amp out.
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Observe the op-amp output. Determine if the op-amp is picking up the
system self noise and then amplifying it. Determine if more gain is needed to
get a more accurate reading.
Divide the RMS noise signal by the gain to determine the self-noise and
compare it to the design specifications.
3.4 Distortion Test
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Consult with other engineers on the best method of doing this.