Chapter 2 — Checking Procedure
Checking Procedure
2238 Mediator Integrating Sound Level Meter
Service Manual
BI5043–13
19
Table 2.9 Tone Burst Test
Note: The 2238 handles both Fast and Slow through the same circuit. If there is a
fault, then the whole unit (excluding the microphone and preamplifier) must be
returned as an FRP.
2.3.11 Octave Filter Upgrade
Following an upgrade with Octave Filter ZT0328, the service technician can choose
to perform the following tests on any or all of the 29 Center Frequencies.
● Remove the microphone and use adaptor JJ2614 and JP0144 to connect the 2238
to a generator.
● Press , then to About, then to select. The last line on the 2238 display
should read Filter set: Yes. This shows that you have installed the filter set.
● Press once to return to main menu.
● First, set up to generate a reference signal. Press and down to Weightings,
then to select. Start by using to set the bandwidth to BB/S, then
press down to Freq. Wtg. and to set it to L, then to OK and to
Close and return to the active display.
● Set the generator to an appropriate level, and adjust the output until the display
on the 2238 reads 100.0dB.
● With this as a reference, press then and to select Weightings.
Use to set the bandwidth to either 1/1-octave/F or 1/3-octave/F.
● The 1/3-octave/F setting gives access to all 29 Center Frequencies, while the
“1/1-octave/F setting provides only 9. Then press down to “Center Freq.
and to set it to the desired frequency. Press to OK and to Close.
● The 2238 display should read LxxHzFP where xx is your center frequency. If not,
use while in the active display to go down to the first line, and until it reads
correctly.
● Input a signal from the generator at this frequency. The 2238 display should now
read 100.0 dB
±0.5dB.
● Repeat this sequence for the remaining selected frequencies.
Note: When measuring frequencies of 50Hz or under, set the weighting to 1/3-
octave/S. This prevents the reading from short term variations due to the low
Tone Burst
2000Hz
Acceptance Criteria
in dB re 1µVRMS
Actual
Reading
Reference 96.0dB 96.0dB
Fast (LCFP) – 200ms 95.0±1.0
Slow (LCSP) – 500ms 91.9±1.0
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