Crown Audio IQ-USM 810 사용자 설명서
©2000 Crown International, Inc.
IQ-USM 810 Service Manual
4-2 Maintenance
130447-1 Rev. A
4.4 IQ Message String Syntax
4.4.1 Host to Device Messages
The following syntax is used for host to device mes-
sages:
Send: XX XX XX XX XX; Description
sages:
Send: XX XX XX XX XX; Description
XX:
A byte of the message explicitly given in hexadeci-
mal.
XX:
XX:
A byte of the message as defined by the two-letter
codes in Section 4.2.
Description:
Description:
A short phrase to indicate the function of
the message string. The description is added for refer-
ence only. It is not sent as part of the Ucode message.
ence only. It is not sent as part of the Ucode message.
4.4.2 Device to Host Messages
The following syntax is used for device to host mes-
sages.
Return String: XX XX XX XX XX
sages.
Return String: XX XX XX XX XX
XX:
A byte of the message explicitly given in hexadeci-
mal.
XX:
XX:
A byte of the message as defined by the two-letter
codes in Section 4.2.
XX:
XX:
A byte of the returned message that requires range
testing in accordance to the associated test.
4.5 Standard Initial Conditions
The following tests assume this setup unless stated oth-
erwise.
Unit under test built and programmed as documented,
less top cover and labels.
Preset 32 loaded
Inputs set to line mode.
Input potentiometers set to 0 dB.
Unit under test powered by 120VAC
Unit under test connected to test computer via the
RS232 connector with constant IQ communication at
115.2 K baud.
Output Impedance of Audio Sine-wave Source: 50 W
balanced.
Audio Output Load:
erwise.
Unit under test built and programmed as documented,
less top cover and labels.
Preset 32 loaded
Inputs set to line mode.
Input potentiometers set to 0 dB.
Unit under test powered by 120VAC
Unit under test connected to test computer via the
RS232 connector with constant IQ communication at
115.2 K baud.
Output Impedance of Audio Sine-wave Source: 50 W
balanced.
Audio Output Load:
≥
10 kW balanced.
4.6 Test Procedures
4.6.1 LOAD PRESET 32
Note: Preset 32 is the factory default test preset. This preset
sets the audio paths straight through (no gain, filters, or pro-
cessing) to their respective AUX outputs. Main outputs A and
B are driven from inputs 1 and 2 respectively.
sets the audio paths straight through (no gain, filters, or pro-
cessing) to their respective AUX outputs. Main outputs A and
B are driven from inputs 1 and 2 respectively.
Procedure:
Send the select preset 32 command:
Send: DA DT CT B2 7F 09 20 CS; Select preset 32
Send the select preset 32 command:
Send: DA DT CT B2 7F 09 20 CS; Select preset 32
Send the load preset command:
Send: DA DT CT B4 7F 09 01 CS; Load preset
Send: DA DT CT B4 7F 09 01 CS; Load preset
Note: The load preset command must be sent within approxi-
mately 2 seconds of the select preset command.
mately 2 seconds of the select preset command.
Note: Preset 32 may also be selected using the front panel
controls.
controls.
1) Use the “
∧
” and “
∨
” buttons to select preset 32. (Dis-
play shows P32.)
2) Press “SEL” button.
2) Press “SEL” button.
4.6.2 OUTPUT NOISE
Spec:
LINE mode:
≤
–75 dBu and
≥
–80 dBu, 22 Hz to
22 kHz bandwidth.
Note: The test and printed specifications do not match. The
printed specifications are for an "A" weighted 20-Hz to 22-kHz
bandwidth. Production tests do not use "A" weighted filtering.
printed specifications are for an "A" weighted 20-Hz to 22-kHz
bandwidth. Production tests do not use "A" weighted filtering.
Initial Conditions:
Inputs terminated at
≤
50 W bal-
anced. Bandwidth = 22 Hz to 22 kHz.
Procedure:
Procedure:
Verify each main and AUX output meets
spec.
4.6.3 FREQUENCY RESPONSE
Spec:
+0.1, –0.6 dB from 20 Hz to 20 kHz.
Initial Conditions:
Normalized to a reference of a
1 kHz, 0 dBu signal.
Procedure:
Verify each main and AUX output meets spec with one
of the following methods:
A 10+ point, logarithmically spaced, sweep.
Testing at these frequencies: 20 Hz, 100 Hz, 500 Hz
1 kHz, 5 Hz, 10 kHz, and 20 kHz.
Procedure:
Verify each main and AUX output meets spec with one
of the following methods:
A 10+ point, logarithmically spaced, sweep.
Testing at these frequencies: 20 Hz, 100 Hz, 500 Hz
1 kHz, 5 Hz, 10 kHz, and 20 kHz.
4.6.4 HARMONIC DISTORTION
Spec:
< 0.030 % and > 0.001 % THD+N, with a 22 Hz
to 22 kHz bandwidth.
Initial Conditions:
Initial Conditions:
Input signal: 1 kHz, 0 dBu.
Procedure:
Verify each main and AUX output meets
spec.
4.6.5 COMMON MODE REJECTION
Spec:
>40 dB at 60 Hz in line mode, 22 Hz to 22 kHz
bandwidth.
Procedure:
Input a 60 Hz +18 dBu balanced signal.
Monitor the associated AUX output with a 22 Hz to
22 kHz bandwidth and set the reference.
Change the input to common mode (same frequency
and amplitude)
Verify the associated AUX output is attenuated at least
40 dB below reference with a 22 Hz to 22 kHz band-
width.
Procedure:
Input a 60 Hz +18 dBu balanced signal.
Monitor the associated AUX output with a 22 Hz to
22 kHz bandwidth and set the reference.
Change the input to common mode (same frequency
and amplitude)
Verify the associated AUX output is attenuated at least
40 dB below reference with a 22 Hz to 22 kHz band-
width.