3
-
at an input voltage of approx. 3 Vpeak the protection circuit reacts and tries continuously to re-start!
The protect-LED blinks with the same frequency.
-
Repeat the test with f = 14 Hz; the power amplifier should not switch off.
5.8 HF-PROTECTION CIRCUIT TEST
Caution:
it is mandatory to drive the power amplifier without load resistors connected.
Drive the power amplifier with a +20 dBu sine burst signal (40 mS ON, 960 mS OFF)
f = 100 kHz
applied to
each channel at a time. The protection circuit should react. The power amplifier tries to re-start continuously.
The PROTECT LED blinks with the same frequency.
Repeat the test with
f = 50 kHz
; the power amplifier should not switch off.
5.9 LED INDICATOR TEST
apply a 1 kHz sine signal and increase its level. At approximately -30 dBu the SIGNAL LEDs should light and
at about +4 dBu the LIMIT LEDs light.
6. Level channel A & B
6.1
voltage amplification
unit
input
U(E)
test point
U(A)
load resist.
test freq.
Force
CH. A/B
0.9dBu
SPEAKER A/B
42.4V
∞
1kHz
Force
CH. A
0.9dBu
BRIDGED OUT
84.8V
∞
1kHz
Eliminator
CH. A/B
0.5dBu
SPEAKER A/B
49V
∞
1kHz
Eliminator
CH. A
0.5dBu
BRIDGED OUT
98V
∞
1kHz
6.2 MAXIMUM INPUT LEVEL: U (E) = +21 dBu
7. GROUND LIFT switch
the circuit ground (at the input or the output connector) is measured versus the common ground of the
enclosure (contact at the ground terminal, located on the rear panel - or common ground of the mains cord).
position of the switch:
GROUNDED
: R = 0
Ω
UNGROUNDED
: R = 5
Ω
8. Amplitudes - non-linearities
-
testing with load resistor 8
Ω
, dual mode
- MDW = 80 kHz
measuring
at nomonal output
remark
Force
Eliminator
THD+N ( f = 1kHz )
<0.05%
<0.05%
IMD-SMPTE
<0.08%
<0.08%
60Hz, 7kHz
DIM 30
<0.03%
<0.03%
3.15kHz, 15kHz
9. frequency response
the frequency response is linear. (please mind the cut-off frequencies)
low cut-off frequency
high cut-off frequency
-3dB
fl < 10Hz
fh = 85kHz
-1dB
fl = 13Hz
fh = 45kHz
10. factory default
BRIDGED MODE
switch se to
NORMAL
INPUT ROUTING
switch set to
DUAL/STEREO
LEVEL
controls set at their clockwise margin
