Gai-tronics 69439-001 External Audio Interface (EAI) Uživatelský manuál stáhnout pdf (Strana 8)

Pub. 42004-677L2C

Model 69439-001 External Audio Interface Page: 8 of 9

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Frequently Asked Questions

Q: When the card rack is powered, but the MCU is either not installed or not properly configured, is

there some feature of the EAI that can aid in determining if a connection to one of the audio inputs is

properly wired?

A: Yes. The bottom four LEDs, labeled AUD

IN #1, AUD IN #2, AUD IN #3, and AUD IN #4, are

controlled by the EAI independently of the MCU. Each LED shows the detected audio status of the

600-ohm audio input corresponding to the LED’s label. After injecting a signal on a wire in question, one

can use the associated LED to tell if the wire is connected.

Q: Is there a common reason why one of the bottom four LEDs, labeled AUD

IN #1, AUD IN #2, AUD

IN #3, and AUD IN #4, may never turn off?

A: Yes. The 600-ohm audio input corresponding to the LED might be detecting excessive noise. One

common cause of this excessive noise is a ground problem.

Q: Why are the levels on the audio outputs 6 dB higher than specified?

A: A 600-ohm resistor is not connected across the audio output.

Q: Must the resistor network be installed when using the contact input terminals?

A: Yes; if not, the system will report a fault condition.

Specifications

Electrical

Board

Power ................................................................................................ 575 mA maximum @ +5 V dc ±10%

150 mA maximum @ +12 V dc ±10%

150 mA maximum @ −12 V dc ±10%

1.0 kHz Sine Wave Detectors

NOTE: Use a card rack audio bus when measuring amplitude.

In-range frequency........................................................................................ (within) inside 1.00 kHz ±1%

In-range amplitude on card rack audio bus......................................inside 4.24 Vp-p (1.50 Vrms) ±1.5 dB

Out-of-range frequency............................................................................. (beyond) outside 1.00 kHz ±3%

Out-of-range amplitude on card rack audio bus.............................outside 4.24 Vp-p (1.50 Vrms) ±4.5 dB

600-Ohm Audio Input

Audio input voltage.................................................................................2.82 Vp-p (1.00 Vrms) maximum

Audio input to card rack audio path frequency response................................ 250 Hz to 12.0 kHz ±1.5 dB

Audio input to card rack audio path distortion + noise............................ THD + noise <0.5% @ 1.00 kHz

Audio input impedance........................................................................... ≥24 kΩ from 250 Hz to 12.0 kHz

Audio detect level for LED.................................................................282 mVp-p (100 mVrms) maximum

Audio not detected threshold for LED..............................................28.2 mVp-p

(10.0 mVrms) minimum

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Gai-tronics 69439-001 External Audio Interface (EAI) Uživatelský manuál Strana 8