ACCEPTANCE TESTING
5-21
Audio voltmeter
Specification
Level accuracy:
±3% ±3 mV ± resolution 20 Hz to 50 kHz (DC and 20 Hz to 50 kHz
when DC coupled)
Resolution:
1 mV or 1% of reading.
Test equipment
Description Minimum specification Example
LF generator 50 Hz to 50 kHz 30 mV to 5 V RMS. IFR 2965
DC power supply 0 to 50 V
DVM DC measurement and AC measurement 20 Hz to
50 kHz.
Solatron 7150+
(1) Refer to Results table 5-26 on page 5-46. Connect the equipment as shown in Fig. 5-13,
connecting the LF generator output to the UUT AF input and via a T-piece to a DVM.
(2) Press [HELP/SETUP], [Setup], [AF Filters], [Factory Preset], [Return], [Return], [Return].
Set the UUT to [AF TEST] press [AF Filter], [50 kHz LP] to set the Audio Input filter to
50 kHz Low-pass. Press AC/DC coupling until AC coupled is displayed.
(3) Set the DVM to measure Volts AC and the LF generator to frequency 1 kHz , level 30 mV
RMS (adjust until the DVM indicates as close to 30 mV as possible). Check that the level
indicated on the UUT voltmeter is within ±3% ±3 mV ± resolution of the level indicated on
the DVM.
(4) Repeat step 3 with LF generator levels of 200 mV, 0.4 V, 0.8 V, 2 V, 4.5 V.
(5) This step is a functional check only and confirms that the audio filters switch in correctly
with minimal insertion loss. Press [HELP/SETUP], [Setup], [AF Filters], [Factory Preset],
[Return], [Return], [Return].
• Set the UUT AF filter to 15 kHz LP and check that the UUT voltmeter indicates within
±6% ±3 mV ± resolution of the level measured with the 50 kHz LP.
• Repeat with the 300 to 3.4 kHz BP filter.
• Repeat with the 50 to 15.0 kHz BP filter.
• Set the LF generator to 100 Hz and set the UUT filter back to 50 kHz LP. Note the
reading and then set the UUT filter to 300 Hz LP. Check that the UUT voltmeter
indicates within ±6% ±3 mV ± resolution of the level measured with the 50 kHz LP.
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