Aural Exciter Tests ( Model 303 Only) - Aphex COMPELLOR 300 Operating Manual

7.4 AURAL EXCITER Tests ( Model 303 Only)
Id
NOTE... Disconnect P401 from the AURAL EXCITER board at H401 to enable inser-
tion of test signals. The normal power supply via H402 is still retained for
the following tests, which are conducted with the power on.
7.4.1 Filter Test
This test should be done using a tracking generator and spectrum analyzer.
Inject a - 10 dBm signal from the tracking generator to pin 3 of H401 and
monitor the filter output at the DRIVE control clockwise end. Set the ana-
lyzer to sweep at 1 kHz/div. Verify the gain is unity above the cutoff fre-
quency, and that the cutoff frequency tunes with the TUNE control. Observe
that the shape set by the PEAKING control holds through the tune range.
Verify that PEAKING is adjustable from at least 2 dB down to zero.
7.4.2 Harmonics Processor Test
Apply a - 10 dBm, 5 kHz tone to pin 3 of H401. Set TUNE full counterclock-
wise. Set PEAKING and DRIVE full clockwise. Check the signal at the
clockwise end of the MIX pot with an oscilloscope. You should see a wave-
form similar to Fig. 7-3.
Fig. 7-3. Waveform shape appearing at clockwise terminal of MIX pot.
Reduce DRIVE to minimum. The waveform should smoothly resume a
nearly sinusodial shape and diminish in amplitude as DRIVE is reduced.
7.4.3 Mix Return Test
Retain the setup used in the Harmonics Processor Test and return DRIVE to
full clockwise. Monitor the output of pin 1 of H401 with the oscilloscope.
Turn MIX full clockwise. Check that the 1N/OUT switch functions by
observing the output as it changes shape and amplitude.
With the IN/OUT Switch IN, verify that the waveform is similar in shape to
Fig. 7-3. Reduce the MIX Control to zero and observe that the waveform falls
in amplitude and loses the non-sinusodial shape in proportion to mix level.
Check that the signal at pin 1 of H401 is equal to pin 3 when MIX is at zero.
Test & Troubleshooting Procedures 7-5