Kurzweil PC3x - Audio Output; Diagnostic Version 0.20 or Earlier

Diagnostics
Description of Tests
2 - 7
Audio Output
This is not a test that fails. It is an interactive test for the entire audio chain. However for this test
to pass reliably, the MARA Validity and MARA Delay RAM tests should pass. The software
creates waveforms (sine and sawtooth) and stores them in the Delay RAM. Therefore, MARA 1
and its Delay RAM need to be functioning for this test to produce a clean audio waveform.
When you select this test, the LCD displays the following:
Figure 2-6 LCD example, Audio output test
Note: If the diagnostic version is earlier than 0.20, this test is only useful to check the polarity of
the Main Output audio signals. Use the Sine Wave Test on page 2-8 for audio level and distortion
tests. If the diagnostic version is 0.20 or later, follow the on-screen instructions for use.
Warning: This test produces loud sine waves. Before beginning this test, turn the volume slider
on the PC3x and your sound system down to minimum.
Diagnostic Version 0.20 or earlier
To use diagnostic Version 0.19 or earlier to check amplitude, polarity, and frequency response
flatness; an oscilloscope is needed.
1. Move the Volume slider to maximum, then press the Play Sawtooth soft button.
2. A 275 Hz sawthooth with a peak amplitude of +/-0.30V will appear on the Main Left and
Main Right Outputs.
If the polarity is correct, the sawtooth ramp will be positive-going at the Tip contact of
each jack and negative-going at the Ring contact.
If the frequency response is flat, the ramp will be perfectly straight except for three tiny
ripples just before and after the flyback part of the signal.
The volume slider does not act normally during the test so leave it set to maximum. Only the
Main outputs will be driven. When finished checking the Main Output signals, press the Exit
soft button to exit the diagnostic.
The Play Sine soft button will produce a sine wave, also 0.30V peak amplitude, but it is not
pure and thus unsuitable for distortion measurements. Use the Sine Wave Test that follows.
Do not press the Sample Loop soft button. It will hang and require a power cycle to recover.
Running Audio output test
Frequency = 220 Hz
Output = Main outputs
PLAY PLAY SAMPLE
SINE SAWTOOTH LOOP EXIT