JBL 5152, Инструкция по установке и обслуживанию

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F r e q u e n c y R e s p o n s e
( 2 0 H z - 2 0 kHz, + 0 , - 1 d B @ +18 d B m , into 6 0 0 O
Ref. 1 kHz.)
Table 2 outlines the test set-up and s e q u e n c e for
measuring frequency response of the 5152.
J U M P E R S
F i g u r e 13
W A R N I N G
T H I S S E C T I O N O F T H E M A N U A L
C O N T A I N S S E R V I C E I N S T R U C T I O N S
F O R U S E B Y Q U A L I F I E D S E R V I C E
P E R S O N N E L ONLY.
4. Set the C H A N N E L 1 or C H A N N E L 2 level control,
depending on which channel is under test, to
m a x i m u m .
5. Set the oscillator level for a +18 d B m (direct output)
or + 2 4 d B m (transformer output).
6. Measure the distortion of the preamplifier at 3 0 Hz,
2 0 0 Hz, 2 kHz and 20 kHz.
H E W L E T T
P A C K A R D
3 3 3 A
F I G U R E 1 4 , T H D T E S T
S E T U P
M i c r o p h o n e E q u i v a l e n t N o i s e
( - 1 2 5 d B Ref. 0 . 7 7 5 V unweighted, 1 5 0 O s o u r c e
20 kHz equivalent bandwidth).
Using the test set-up, Figure 11 or 12:
1. Set the M I C / L I N E or P H O N O / L I N E / M I C switch
to MIC and the M I X / O V E R R I D E switch to MIX.
2. Install a 5195 transformer into I N P U T 1 or I N P U T 2.
3. Set the C H A N N E L 1 or C H A N N E L 2 level control
to m a x i m u m and the c h a n n e l not under test to
minimum.
4. Set the oscillator to 2 k H z and adjust the output
level of the 5152 to 0 d B m .
5. Measure the input signal.Typical readings are - 7 1
d B , indicating a gain of 71 d B .
6. Install the 20 kHz filter, Figure 11.
7. Disconnect the oscillator from the preamplifier.
8. Measure the noise level at the output of the 5152.
Typical readings are - 5 4 d B m .
9. Add the input level and noise m e a s u r e m e n t to
calculate the equivalent input noise.
E X A M P L E - 7 1 d B Ref. 0 d B m I N P U T L E V E L
- 5 4 d B Ref. O d B m N O I S E L E V E L
- 1 2 5 d B Ref. O d B m E Q U I V A L E N T
I N P U T N O I S E
10. T h e calculated equivalent input noise figure should
be - 1 2 5 d B (Ref. 0 d B m ) or better.
D C V o l t a g e M e a s u r e m e n t s
All D C voltage m e a s u r e m e n t s are with respect to
ground and are m a d e using a Fluke 8 0 0 0 A with a line
voltage of 120 V A C .
Voltages s h o w n with two readings on the schematic
indicate the two states of the T R I P D E T E C T O R and
F E T G A T E when properly operating.
E X A M P L E T R I P D E T E C T O R
+ 0.460 V N O T G R O U N D E D
+ 86.9 mV
T R I P
D E T E C T O R
G R O U N D E D
T A B L E 2
A C V O L T M E T E R O R
H A R M O N I C D I S T O R T I O N A N A L Y Z E R
Figure 1 + T H D test set up.
T H D
( < 0 . 2 % , 30 H z - 2 0 k H z ) .
Using the test set-up, Figures 9 and 14:
1. Set the M I C / L I N E or P H O N O / L I N E / M I C switch
to L I N E .
2. Set the M I X / O V E R R I D E switch to MIX.
3. Install j u m p e r s between terminals #4 and #5 and
between terminals #8 and #9 of e a c h 9-pin socket,
X T 3 0 1 and X T 3 0 2 , Figure 13.
N O T E : To u s e Table 2, read d o w n a n d
a c r o s s . N u m b e r s under L I N E , M I C a n d
P H O N O represent test s e q u e n c e .
F r e q u e n c y R e s p o n s e T e s t a n d
O p e r a t i o n a l S e q u e n c e .
L i n e L i n e M i c P h o n o
C o n n e c t test oscillator to input. 1
1
C o n n e c t test oscillator to input using
1
Figure 9 or Figure 1 2 .
C o n n e c t test oscillator to input using
1
Figure 10.
Set M I C / L I N E or P H O N O / L I N E / M I C 2
switch to M I C .
Set M I C / L I N E or P H O N O / L I N E / M I C
2 2
switch to L I N E .
Set P H O N O / L I N E / M I C switch to P H O N O .
2
C o n n e c t the A C voltmeter a n d a 6 2 0 O,
3 3 3
1 W load resistor a c r o s s output terminals
m a r k e d D I R E C T a n d G N D .
C o n n e c t the A C voltmeter a n d a 6 2 0 O,
3
1 W load resistor a c r o s s output terminals
m a r k e d HI a n d L O .
Set C H A N N E L 1 or C H A N N E L 2 level
4 4 4
control to m a x i m u m . Set the test oscillator
to 2 k H z and adjustthe amplitude to indicate
+ 18 d B m a c r o s s the D I R E C T a n d G N D
terminals of the O U T P U T strip.
Set C H A N N E L 1 or C H A N N E L 2 level
4
control to m a x i m u m . Set the test oscillator
to 2 k H z a n d a d j u s t t h e a m p l i t u d e t o indicate
+ 2 4 d B m a c r o s s the HI a n d L O terminals
of the O U T P U T strip.
Voltage gain of the s y s t e m c a n be c h e c k e d 5
5 5 5
by substituting the value in the formula:
A
v
( d b ) = 2 0
Loq
1 0
ClO
Input voltage of the s y s t e m c a n be
m e a s u r e d by connecting the A C voltmeter
6
6 6 6
at the I N P U T terminals.