Ecler DPA2500T, Service Manual

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DC OUT
- In order to run this test, do not connect any load
impedance.
- Adjust the signal generator to deliver a signal with
a frequency below 5Hz, and select the 3V scale
output level.
- Connect the oscilloscope to the unit's output,
5V/div vertical scale, 20ms/div time base. Use a
10x attenuating test probe.
-
Turn on the signal generator. Increase its output
level until the thyristor starts actuating, and the
observed signal becomes the typical sawed sine
wave. Use the oscilloscope's memory bank in
order to observe carefully this fact.
VERIFICATION USING MUSIC
Verify the unit's sound quality, with should be distortion- and noise-free. Once the unit is turned in and its
STANDBY cycle time has elapsed, the output relays release, but no annoying noise is heard through the
loudspeakers. Also check that all potentiometers can run smoothly their whole sweep, without noise 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 all in- and outputs. Short the output terminals while carrying
amplified signal, wait approximately 5 or 10 seconds, after with the unit should perform a general reset.
Verify the PROTECT indicating LED lights up, the output signal is cutted off, and the STANDBY cycle is
correctly done. Once the short-circuit is removed, the unit recovers normal functioning.
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.