Ecler APA1000, Service Manual

Page: 44 / 138

author:
Queralt
date:
000519
approved:
num:
51.0027
version:
01.01
VERIFICATION PROCESS
title:
APA POWER AMPLIFIERS
PRELIMINAR:
- Set the MONO-STEREO switch to STEREO.
- Check the GROUND-LINK switch.
- Place a mini-jumper at connector J123's terminals (power supply).
- Select the subsonic filter switch to OFF.
- Verify that the correct cables and connections are used.
- Connect the unit's mains power cable to a variac output, and leave it on the 0V
output voltage position.
- Keep an ammeter prepared to verify the unit's current demand.
VERIFICATION
- Turn on the unit without any load connected to its outputs by setting the main power
switch to its ON position. Increase slowly the variac's output voltage until it reaches its
maximum value, which is 230Vac. At this point, verify that the unit's bias current
demand keeps its factory adjusted value and, if not, proceed to readjust this parameter.
After this, fix the adjustment devices with sealing lacquer. Also check that the Power
On led is lit.
- Replace the ammeter by the corresponding fuse. Warning! The power supply will be
charged! Note: to discharge the power supply, apply a 0dB 2KHz input signal to the
unit and turn its mains voltage down to 0V by reducing the variac's output voltage.
- Turn off the unit and afterwards on again in order to verify the time it remains in
STAND-BY mode, which should last approximately 10 seconds. Also verify that when
the unit is turned on, the cooling fans run up until their maximum speed.
- Verify both XLR and JACK input terminals, also check the attenuation values by
sweeping their potentiometers between -v and 0dB.
∙ Verify the amplifier's output power while connected to the mains power supply:
- APA1400 635W 51V on 4
Ω
- APA1000 440W 42V on 4
Ω
- APA600 275W 33V on 4
Ω
- Verify the ANTICLIP system is functioning correctly by increasing the input signal
level up to values higher than 0dB. The output signal should be smoothly clipped.
Verify that if a mini-jumper is placed at the test terminals (which are located near the
VTL5C8 package), the ANTICLIP system switches on earlier, making the clipped signal
appear even more smoothened. Check that the front panel CLIP leds are lit, and
observe that, when the input signal is damped 1 or 2 dB, the CLIP indicator leds turn
off. Do not retire the mini-jumper.
- While applying a 0'5V input signal, verify the unit's frequency response bandwith,
which should be linear between 20Hz and 20KHz. The output signal should appear
ECLER
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