HP 8924E, Assembly

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Chapter 14, Diagnostics Descriptions
Description Of Audio Diagnostics (AFDIAGS3)
N:\mkt\MANUALS\HP8924C\ALR\diagnos.fb
Audio Analyzer 1 Internal Paths
This test checks Audio Analyzer 1’s paths which receives the input from the
Modulation Distribution assembly. The paths are illustrated in
figure 62
,
figure 63
, and
figure 64
.
In Path 1, the audio source is set to DC. The simplest path through the Modulation
Distribution assembly is chosen. The signal passes through Audio Analyzer 1 by
this path to the DVM. In Path 2, the source is set to AC and the signal is peak
detected before being measured by the DVM. In Paths 2 to 4, the gain of the
Programmable Input Gain amplifier is tested for gains of 1, 10, and 100 (0, 20, 40
dB). The input signal is adjusted to keep the signal level in the range of the
circuits that follow. In Paths 5 to 12, the frequency response of the filters are
tested.
Paths 8 and 12 specifically test the optional filters. The presence and identification
of the filters is determined by measuring a DC voltage from a resistive divider on
the filter daughter-board. 0 V corresponds to no filter present; 0.95 to 1.1 V
indicates the 6 kHz high-pass filter; and so forth. Measurement limits are based on
the specified frequency response.
The measurement limits are
±
10% of nominal
±
10 mV offset for levels not
involved with frequency responses (Paths 1 to 5). Through the filters, the
measurement limits vary:
±
20% in the passband and much wider in the stopband
(Paths 6 to 12).
The failure codes for Audio Analyzer 1’s internal paths are as follows: