Crown Com-Tech 1610, Service Manual

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Com-Tech 810 and 1610 Amplifier Service Manual
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6-3
Rev. 0
Figure 6.3 10 kHz square wave response
Procedure: Load each channel to 8 ohms. Inject a 20
kHz sine wave into channel 1 and, if the amp is a
CT-
810, increase the level to 48 VAC at the output. If the
amp is a
CT-1610 increase the level to 64 VAC. Termi-
nate the channel 2 input with 600 ohms. Measure less
than 48 millivolts AC at the output of channel 2 on a
CT-
810 (less than 64 millivolts for a CT-1610). Repeat for
channel 2 by driving channel 2 and terminating chan-
nel 1. Measure less than 48 millivolts at the output of
channel one for a
CT-810 (less than 64 millivolts for a
CT-1610).
6.2.13 Output Power
Spec: Maximum Average Power at 0.05% THD. Both
channels driven.
Com-Tech 810:
8 ohm = 300 watts/channel maximum
4 ohm = 480 watts/channel maximum
12.5 ohm (70V mode) = 455 watts/channel
maximum
Com-Tech 1610:
8 ohm = 535 watts/channel maximum
4 ohm = 860 watts/channel maximum
6.25 ohm (70V mode) = 955 watts/channel
maximum
Procedure: Load each channel to 8 ohms. Inject a 1
kHz sine wave and, on a
CT-810, measure at least 49.0
VAC at the output of each channel with less than 0.05%
THD. With a
CT-1610, the VAC measurement should be
65.4. Load each channel to 4 ohms. Inject a 1 kHz sine
wave and, on a
CT-810, measure at least 43.8 VAC at
the output of each channel with less than 0.05% THD.
On a
CT-1610 the VAC reading should be 58.7. Switch
the output mode switches to 70V. If working on a CT-
410, load each channel to 12.5 ohms, on a CT-1610 the
load should be 6.25 ohms. Inject a 1 kHz sine wave
and, on the CT-810, measure at least 75.4 VAC at the
output of each channel with less than 0.05% THD. On
the
CT-1610, you should measure at least 77.3 VAC.
6.2.14
ODEP Limiting
Spec: Clean limiting into a resistive load (see Figure
6.4).
Procedure: Load each channel to 4 ohms. Set the mode
switches to 70V. Inject a 50 Hz sine wave into each
channel and increase the level for 20 VAC at the out-
put. If the unit is equipped with a fan, stuff a rag into it,
preventing the fan from turning. Observe the wave form
on an oscilloscope. After about 1 minute
ODEP limit-
ing will occur (see Figure 6.4). Once limiting occurs the
wave form will collapse at a rapid rate. Make sure both
channels limit. Remove the load and signal, remove
the rag from the fan, and allow the amp to cool. Put
each channel back into the 8/4 ohm mode.
6.2.15 Fan Operation
Spec: Continuously variable. Varies with ODEP volt-
age.
6.2.16 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 ampli-
fier cycles on and off. It should cycle on and off when
the output reaches approximately 6 Vrms.
20kHz power
0 dB < .01%
Figure 6.4 ODEP limiting wave form