Ecleree MPA4-80, Руководство по обслуживанию

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author:
Queralt
date:
000718
approved:
num:
51.0024
version:
01.00
VERIFICATION PROCESS
title:
EP01-99A
ECLER
- Disconnect the oscilloscope's both channels test probes, and connect them to outputs
3-4.
- Turn up channel three's input triming potentiometer, and check that it's sweep is
complete and smooth. At its maximum position, check that Vo=14V, and that the
output signal monitored on OUTPUT3 is only dependent from the INPUT3 signal.
- Turn up channel four's input triming potentiometer, and check that it's sweep is
complete and smooth. At its maximum position, check that Vo=14V, and that the
output signal monitored on OUTPUT4 is only dependent from the INPUT4 signal.
- Both output signals should have no phase differs.
- Now change the ST/BRIDGE selector to the BRIDGE position, and verify that
OUTPUT3 and OUTPUT4 phase differ has turned to push-pull. However, Vo remains
unchanged, 14V. S.P. CHIV's LED has turned off, and the unit's channels 3&4 section
is now controlled only by channel three's input trimming potentiometer. Turn it up and
leave it at its maximum position.
- At this point, all clip indicators should be lighting. If necessary, add a little bit of level
to the input signal.
- Set the IN1/IN1+IN2 selector to IN1, and verify that the output level as decreased
6dB.
QUALITY CONTROL
All mechanical parts should be visually revised, in order to detect scratches on the
unit's painting; all screws should be on their place,correctly tight and unmarked. Check
out the unit's general presentation.
BURNING (BURN-IN) TEST
Leave the tested unit connected to its correspondent voltage mains socket, applying
input signal and connecting load impedances, and working at 3dB under its maximum
output power level for at least 24 hours.
VERIFICATION USING MUSIC
Verify the unit's sound quality, which should be distorsion- and noise-free. Also check
that all potentiometers can run smoothly their whole sweep, without annoying noises
and crisperings. At their minimum position, check that output signal is completely
cutted off. To ensure that all electrical junctions are well-fixed, hit the tested unit
against your working table, obviously without damaging its outer presentation. Verify
also all inputs and outputs. At last, short-circuit the output terminals while carrying
amplified signal, and verify that once short-circuit is removed, the amplifying stages still
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