Crown Macro-Tech MA-5002VZ Service Manual page 38

MA-5002VZ Service Manual
Type of Test
or Adjustment
19. LED Check,
Current Limit Check
20. 10 kHz Square Wave
Slew Rate Test
21. DC/LF Protect
5-10 Maintenance
Input Signal and
Load Parameters
1-kHz Sine/Sq Wave Turn the amplifier on after being off at least 10 sec-
Various Loads onds. Observe that the ODEP lights come on after
about 4 seconds. The SPI/IOC lights should go off (if
on during delay) at this time. Input a 1-kHz 2 Vrms
sine wave into each channel and observe that the SPI/
IOC lights are on bright. Turn down the input level to
about 0.5 Vrms and observe that the SPI/IOC lights
remain on, but dimly. Remove the input signal and
load the amplifier to 8 ohms/Ch. Insert the 0.5 Vrms
signal again and note that the I
come on green. Change the load to 1 ohm/Ch, switch
to a square wave (20% Duty Cycle), and increase in-
put level to 2 Vrms. Note that the I
turn red. This check also constitutes the Current Limit
Check.
10-kHz Sq. Wave
8 ohm Load With an 8-ohm load on each channel, insert a 10-kHz
square wave and adjust amplitude to produce an
output 10V below clipping (see Figure 5.3). Observe
a 30V/µS (or higher) slew rate. The output waveform
should be stable with no ringing or over-shoot.
4-Hz Sq. Wave
8-ohm Load Insert a 5Vpp 4-Hz square wave with an 8-ohm load
on the output. The protection relay should cycle.
Figure 5.3 10-kHz Square Wave
130446-1 Rev. A
Comments
/I
LOAD LIMIT
/I
LOAD LIMIT
©2000 Crown International, Inc.
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