Fan Operation; Lf Protection; Intermodulation Distortion (Imd); Post Testing - Crown Macro-Tech MA-2402 Service Manual

MA-2402 Service Manual

5.3.12 Fan Operation

Spec:Continuous full speed.
Procedure: Verify operation per above specification.

5.3.13 LF Protection

Spec: Amplifier channel will cycle into protect with .5
Hz 6Vp-p or 2 Hz 6 Vrms sine wave at the output.
Procedure: Inject a 2 Hz sine wave into the input of the
channel under test. Increase the level until the amplifier
cycles on and off. It should cycle on and off when the
output reaches approximately 6 Vrms.

5.3.14 Signal to Noise

Spec: 100 dB below rated 8 ohm power 20 Hz-20 kHz
(A-weighted).
Procedure: Short inputs. Load each channel to 8 ohms.
Measure less than 645 µV at the output of each chan-
nel.

5.3.15 Intermodulation Distortion (IMD)

Spec: 8 ohms, 0 dB = FTC continuous average 20 Hz-
20 kHz power
0 dB < .01%
–35 dB < .05%
5-4 Maintenance
Procedure: Load each channel to 8 ohms. Inject a
SMPTE standard IM signal (60 Hz and 7 kHz sine wave
mixed at 4:1 ratio). Set the 60 Hz portion of the signal
for 50.8 Vrms output. Set the 7 kHz portion to 25%. With
the IM analyzer measure less than 0.01% IMD. Repeat
the test at –35 dB (reference 50.8 Vrms) and measure
less than 0.05% IMD.

5.3.16 Displays

Spec:
Enable - On when low voltage supply is on.
ODEP - Dims in proportion to ODEP limiting.
IOC - On with error amp clip (distortion).
SPI - Flash in sync with amplifier output.
Procedure: Verify indicators per above specifications.

5.3.17 Post Testing

After completion of testing, if all tests are satisfactory,
the amplifier controls should be returned to the posi-
tions required by the customer. If conditions are un-
known or unspecified, factory settings are as follows:
Level Controls: 9 to 11 O'Clock.
Sensitivity Switch: .775V.
Stereo/Mono Switch: Stereo (Dual)
Power: Off.
130445-1 Rev. A
©2000 Crown International, Inc.