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Service Notes
Performance Checks
A l l performance checks are in-cabinet procedures to be used
far checking specifications after repair or for incoming quality
control inspection. Note: AM measurements should be made
w i t h the 5306 and test equipment power cords connected t o
a nominal 120 V A C , 50/60 Hz line voltage.
The f o l l o w i n g test equipment is recommended:
A u d i o Test Osci I l a t o r - Krohn-Hite model 4 1 0 0 , or
equivalent.
Harmonic Distortion Analyzer—Hewlett Packard Model
3 3 3 A , 3 3 1 A or equivalent.
Intermodulation Distortion Analyzer—Crown Model I M A ,
or equivalent.
A C V o l t m e t e r — H e w l e t t Packard Model 4 2 7 A or equivalent.
Oscillator
40dB pad
Krohn-Hite)
> 150ft J
4100
5306 Mixer
Mic
T o 4 0 d B
pad and «
osci i lator
Input(s)
Alternate Oscillator Setup: 2s=600il.
Oscillator
40 dB oad
l 6 2 K a
Krohn-Hite
•620 a
4100
7<r
Configuration—Frequency
Frequency Response
1.
Connect the test oscillator t o any one of the six micro-
phone inputs through a 40-dB pad w i t h a standard
microphone cable. A pad is not necessary when testing
through one of the t w o program inputs.
Z
Connect an AC Voltmeter and a 620-ohm, 1-watt load
resistor across o u t p u t terminals marked " 6 0 0 O
Balanced." Note that the t w o center terminals should
be strapped.
31
With one microphone channel and Master Gain at maxi-
m u m , set the test oscillator frequency t o 1000 Hz and
adjust its amplitude t o indicate 1.95V RMS (+8 dBm) on
the A C voltmeter.
4.
Using 1.95V RMS as a reference level, the mixer should be
w i t h i n + 1.0 dB f r o m 20-20,000 Hz.
Cannon
Zs=150A
XLR-3-12C
To MJc
channel
under
test
AC Voltmeter or
Harmonic Distortion
Analyzer
Hewlett
Packard
;620
427A,
• 1W
333A
or 331A
Oscilloscope
Tektronix
|561B Main
Frame, 3B4 i
Time Base,;
|3A6 Vertical
Amplifier
Response
and THD
5.
Voltage gain of the system can be checked by substituting
the values in the formula A
6.
Input voltage t o the system can be measured by connect-
ing the A C voltmeter at the input terminal.
Total Harmonic Distortion
1.
Using the test set-up illustrated, replace the A C voltmeter
w i t h the harmonic distortion analyzer at the 5306 o u t p u t
terminals.
•2.
With the microphone gain control at maximum and
Master Gain at " 7 , " set the test oscillator at any frequency
between 30 Hz and 2 0 kHz. Adjust amplitude t o indicate
6.2V RMS (+18 dBm) on the distortion analyzer.
3.
Total harmonic distortion of the mixer should be less than
0.2% on any input channel.
Microphone
Channel
Distortion
Microphone
input
levels are as indicated
Distortion
levels of 1% and 0.2% at +78 dBm output
Master Gain at " 5 . "
Microphone Overload Indicator
1.
With the test oscillator still connected t o any one of the
six microphone inputs, connect the A C voltmeter across
the o u t p u t of the oscillator.
2.
Set the microphone gain control at m a x i m u m , and the
Master Gain at " O " .
3.
Set the test oscillator frequency t o 1000 Hz and increase
the amplitude until the overload indicator starts t o flash.
The A C voltmeter should read 40 mV nominal.
6
(dB) =20Log
(-2?-)
V
10
e , n
Characteristics—
for Total
Harmonic
with the
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