Speech Adapter Audio Test Circuit

Speech Adapter Audio Test Circuit

       This article describes a Speech Adapter audio input test
circuit.

      During normal operation a microphone is the standard audio
input device attached to the adapter audio input circuitry and is
used to record speech.  At various times the adapter will require
testing when a microphone may not be available.

      The Test Circuit provides a unique way to test the audio input
circuitry and speech record function without the necessity of
attaching an external microphone.  The Test Circuit is automatically
connected to the audio input when the microphone is disconnected.
This feature will be used in four situations.
1.  During Manufacturing Test when running diagnostics.
2.  When the customer runs diagnostics to identify the cause of
functional failures.
3.  When the dealer runs diagnostics on returned Speech Adapters to
verify failure.
4.  When the IBM Parts Center runs diagnostics to verify failures.

      Thus, the Speech Adapter can be tested in most situations
without the necessity of having a microphone available.
CIRCUIT FEATURES
1.   The test signal source is a Programmable Interval Timer.  (This
device is normally used by the Adapter to generate clock signals.)
Thus, the test signal can be turned on or off and the frequency
changed through program control, by the Personal Computer.
2.   The Test Circuit and microphone are attached to the audio input
at the same point.  Thus, the Test Circuit lists all...