Crown Macro-Tech MA-5002VZ Service Manual page 41

130446-1 Rev. A
Type of Test
or Adjustment
25. Noise
26. Crosstalk Check
27. VZ Modes
Post-testing Procedure:
©2000 Crown International, Inc.
Input Signal and
Load Parameters
No Signal Make sure the sensitivity switches are in the 26-dB
No Load position and the level controls are fully clockwise. Ter-
minate the input with a 600-ohm load. Using a 20 Hz–
20 kHz bandpass filter, measure the noise on the out-
put of the channel under test. Noise should be less
than 574 µVrms (105 dB down from 1300 watts into 8
ohms).
20-kHz Sine Wave Make sure the sensitivity switches are set in the
8-ohm Load 26-dB position. Load each channel to 8 ohms. Insert
a 20-kHz sine wave into channel 1 and adjust for 45
Vrms output. Terminate channel 2 input with 600 ohms.
Measure less than 80 mVrms at the output of channel
2. (Greater than 55 dB down at 20 kHz)
Move the input signal from channel 1 to channel 2
and the 600-ohm termination from channel 2 to chan-
nel 1. Ensure there is 45 Vrms at the output of chan-
nel 2. Measure less than 80 mVrms at the output of
channel 1.
1-kHz Sine Wave Note: VZ-ODEP mode was checked during the ODEP
8-ohm Load test, Step 23. I.M.D. and 1-kHz power checks ad-
equately tested the VZ (AUTO) mode. LOCK HIGH (if
present) was checked adequately in the static bal-
ance adjustment check, Step 12. Place the VZ Mode
Switches in LOCK LOW (see Figure 5.4). With an
8-ohm load on each channel, insert a 1-kHz sine wave
into each channel. Clipping should occur at approxi-
mately 36 Vrms (410 W).
At the completion of testing, replace the 30 A fuses (if
testing was done at 100–120VAC), and set all switches
per customer request. If none are specified by the
customer, the following are standard factory settings
for original shipment:
Dual Mono Switch: STEREO position.
Sensitivity Switches: Both to 1.4V position.
Compressor Switches: Both to FAST position.
LOI Switches: Both to ON position.
VZ Mode Switches: Both to VZ–ODEP position.
Level Controls: Both down (counter-clockwise) fully.
In most applications, VZ–ODEP is the VZ Mode to use
for best thermal performance.
MA-5002VZ Service Manual
Comments
Maintenance 5-13