Leave the unit connected to its nominal mains voltage during 24 hours.
SAFETY VERIFICATION TESTS
Preliminary:
Unplug the unit to be tested from the mains outlet.
Short all ground terminals from signal inputs, outputs and other external connectors, except the
mains plug’s ground.
Turn ON the unit’s main power switch.
Ground continuity test:
Connect the tester probes between the mains ground contact and the unit’s backside main ground test
point. When applying a 10A current, verify that the ground impedance is lower than 0’1Ω.
Electrical insulation test:
Connect the electrical insulation tester probes between the mains outlet ground contact and both shorted
mains input poles.
Adjust the tester’s current limit down to 10mA.
Apply 1500Vac during 5 seconds.
The unit’s insulation should be able to resist this voltage, without generating spurious sparks or a
sparkover effect, and the tester may not detect any malfunction.
CAUTION: Do not disconnect nor touch the test probes until the test has finished completely!
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.
LE R
51.0175
version:
date:
title:
061018
project:
VERIFICATION PROCESS
M10-05
product:
AC-6
51-0175-0100 M10-05 AC-6 Àngles.doc 1 of 5
Page 46
AC-6 MIXING CONSOLE – VERIFICATION PROCESS WITH MU SIC.
Input sensitivities:
LINE -10dB
PHONO -40dB
CD 0dB
MICRO -50dB
MIX 0dB
RETURN 0dB
Output levels:
REC A 0dB
REC B 0dB
OUT 1 0dB/+6dB* (Bal)
OUT 2 0dB/+6dB* (Bal)
SEND 0dB
CUE 0dB
HEADPHONES 200mW /200Ω
* Internally selectable
Initial Control position:
1. TREBLE, MID and LOW tone control centred.
2. GAIN control centred.
3. MASTER 1 and 2 at maximum level.
4. CROSSFADER centred.
5. FADERs to maximum position.
6. PHONO/CD/LINE selection buttons switched to CD.
7. PRE/POST switched to PRE.
8. XFADER A-OFF-B selector switches centred.
9. Release PFL pushbuttons.
10. OUT1-MIX-OUT2 Vu-meter selector centred.
11. BALANCE control centred.
Note: Any change or manipulation on the unit ’s function select ion switch es, like input s electors, aux sends ,
etc should not have any influence on the mixer’s output sound quality, as for instance appearance of hum
noise, switching noise, faders scratches, etc. During the ve rification of fader sweeps, please note besides
the correct attenuation curve, that the output signal remains free from scratch noise. In every case it is
recommended to read carefully this verification procedure manual before checking the unit, in order to
avoid errors while validating results.
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Page 47
VERIFICATION
1. Connect the unit to a 230Vac mains outlet.
2. Check the main power switch, POWER. Leave it ON.
3. Verify that the three green power indicating leds are lit (+5V, +18V and –18V).
4. Connect an amplifier to the unit’s REC A output.
5. Before applying any input signal, verify that when manipulating the input selection switches
(PHONO-CD-LINE, MICRO-CD-LINE) the background noise on every position remains low and
free from hum, switch noise and scratches.
6. Connect a CD player to the unit’s channel 1 CD Input.
7. Verify that the Signal Present (SP) led lights up (in green).
8. Watch the Vu-meter (MIX). Both channels, L and R, show approximately a 0dB level. Turn up th e
input gain level in order to light up all of the Vu-meter’s leds, and check that all of them are in use.
9. Check that when a +10dB input level is given, the red PEAK-indicating warning led lights up.
10. Press the PFL selection switch, and check that it’s yellow indicating led also lights up.
11. Verify that the PFL MONITOR Vu-meter also shows level on both L and R channels, and when
increasing signal levels, all of the leds light up.
12. Verify the GAIN function: +15dB when turned to the right, -15 dB when tu rned to the le ft. Return th e
GAIN knob to its central position.
13. Verify the TREBLE, MID, BASS tone control. Cut-type tones.
14. Check that the MIX Vu-meter shows increasing or decre asing levels as a function of the FADER
position.
15. When testing the fader, check that when it’s moved up and down, the output signal remains f ree
from scratch noise. Leave the fader up to maximum level.
16. Verify that when XFADER OFF is chosen, the crossfade r does not have any function or influence
on the output signal.
17. XFADER A-OFF-B selector verification.
• Select posi tion A. Verify that the XFADER acts correctly, as when moved to the left (A) there is
music on the output, and when moved to the right (B) the output signal disappears.
• Select positi on B. Verify that the XFADER acts c orrectly, as when mo ved to the left (A) the output
signal disappears, and when moved to the right (B) there is music on the output.
• Verify the crossfader response curve by modifying its shape with the XF SHAPE control knob.
When turned to the left, transition is smooth, when turned to the right the transition becomes
faster.
18. Verify the PFL send. Connect a 200 to 600Ω headphone set into the jack outlet.
• Turn the SELECT knob to its central position.
• Verify the VOLUME control knob sweep.
• When turnin g the SELECT potentiometer to the right side (MIX), the headpho nes play the signal
from the unit’s mix bus.
• Slide down the FADER to its minimum level, and check that the headphones remain in silence.
• Turn the SELECT p otentiometer to the left side (PFL), the headphones play now the music taken
from the PFL bus.
• Release the PFL pushbutton; the output signals are cutted off.
19. Auxiliary send AUX. Connect the output signal on the SEND outlet.
• Verify the AUX SEND volume sweep.
• Verify the PRE/POST selection switch. When switched to PRE, the SEND output signal is not
affected by the FADER position. When switched to POST, the output level depends on the
FADER.
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20. Repeat the procedure from step 6 to 19 on the other inputs.
21. Verify the PHONO inputs.
• Without signal, but using an input charge (a pick-up capsule, or if not available a 600Ω load
impedance) the output signal should be free from hum and/or hiss.
• While applying input signal (music), verify the RIAA filter response and check a correct balance
between low and high frequencies (high and low tone). Check also that when an independent
sound source is connected to the RCA-type CD input located near the PHONO plug, its signal is
not transferred onto the PHONO channel (crosstalk). To ensure this fact, try this when
disconnecting the input signal from the PHONO input.
22. Verify the MICRO inputs.
• Connect a balanced microphone with phantom supply to the unit’s backside XLR-COMBO-type
socket. Check the OFF-PHANTOM switch. When turned OFF, the microphone shouldn’t work.
• Speak into the microphone and check the sound quality.
• Verify the CMRR, as the output signal should sound clear and free from hum and hiss.
Note: the MICRO input is usable both through the XLR and Jack inlets, as it uses a co mbo-type
input socket. Verify both connection types.
23. Verify the MIX input.
• Connect a CD player to the unit’s MIX input.
• Check that the output signal is correct. Use any of the REC A or B, OUT 1, OUT 2 etc outputs
as reference.
24. Verify the RETURN input.
• Connect a CD player to the RETURN input.
• Use any of the REC A or B, OUT 1, OUT 2 etc outputs as reference.
• Check that the AUX RETURN volume control functions correctly.
• Press the PFL signal send. Verify that the yellow indicating led lights up.
• Verify that the returned signal is available through the headphones with a good sound quality.
25. Verifying the TALKOVER system.
• Connect a microphone into channel 5, and choose the MICRO option on the selection switch.
• Connect a CD player to channel 1, and choose the CD option on the selection switch.
• Connect an amplifier to output OUT 1.
• While the faders and master controls are moved to the maximum level, the output signal should
carry both the music from the CD player and the speech from the microphone, mixed in a
balanced proportion.
• Press the MIC5 pushbutton. Check that a red led indicator lights up.
• When talking into the microphone now, the music form the CD player should be damped.
• Repeat this test while selecting different options on the TIME and ATT control knobs.
• Repeat this test procedure for channel 6 also.
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26. Verify the outputs.
• Connect a CD player to the unit’s MIX input.
• Connect the amplifier to the unit’s OUT 1 (bal) L&R output.
• Verify the unit’s main MASTER 1 fa der sweep; check that when MASTER 1 is moved down to
its minimum level the output signal is cutted off. Slide the MASTER 1 fader up to its top again.
• Verify the L+R selector. Check that the yellow indicating led lights up.
• When disconnecting one of the input channels, the output signal appears to be the same on
channel L and R, but with a 6dB level drop. Release again the L+R pushbutton.
• Verify the BAL 1-2 balance control.
• Check the OUT 2 (bal) output.
• Verify the unit’s MASTER 2 fader sweep; check that when MASTER 2 is moved down to its
minimum level the output signal is cutted off. Slide the MASTER 2 fader up to its top again.
• Check the CUE o utputs. The SELECT potentiometer should be turned to its right (MIX). Verify
now the CUE potentiometer sweep and attenuation.
• In case that during this testing procedure the outputs REC A and REC B have already been
verified, it will not be necessary to test them again.
Note: during the complete testing procedure, verify permanently the correct addressing between
the inputs and outputs, specially concerning on L and R channelling, to verify the unit’s internal
signal connections.
Outputs Level/Minimum Load OUT 1 (BAL) 0(+6)dBV 600Ω 1 (2)V
OUT 2 (BAL) 0(+6)dBV 600Ω 1 (2)V
REC A 0dBV/1kΩ
REC B 0dBV/1kΩ
SEND 0dBV/10kΩ
CUE 0dBV/10kΩ
HEADPHONES 200mW/200Ω
Maximum Input level (full gain) PHONO -21dBV
LINE +9dBV
CD +11dBV
MICRO -31dBV
Frequency Response PHONO RIAA±0.5dB
LINE/CD 10Hz÷40kHz -1dB
MICRO 10Hz÷30kHz -1dB
THD+N PHONO <0.03%
LINE <0.02%
CD <0.01%
MICRO <0.03%
RETURN <0.02%
MIX <0.02%
CMRR MICRO >75dB 1kHz
Signal Noise Ratio PHONO >95dB
LINE >102dB
CD >105dB
MICRO >85dB
RETURN >105dB
MIX >105dB
Tone control BASS -30/+10dB
MID -25/+10dB
TREBLE -30/+10dB
Kill Filters LOW 200Hz
(cut frequency at -6dB) HIGH 6.5kHz
Slope 12dB/oct in all the cases MID 200Hz & 6.5kHz
Phantom voltage +18VDC/5mA max.
Mains 90-264 VAC 47-63 Hz
Power consumption 47VA
Dimensions 482.6x355x142.5mm