Zenith J584W - Page 13

RF, IF AND MPX ALIGNMENT PROCEDURE FOR CHASSIS
1WJR55 , 3WJR50,50Z, 3WJR52,52Z
11
STEP
CONNECT
GENERATOR
TO
DUMMY
ANTENNA
CONNECT
VTVM/
SCOPE TO
INPUT
SIGNAL
FREQ.
SET DIAL
TO
ADJUST
PURPOSE
PREFERRED METHOD - WITH AM SWEEP GENERATOR
NOTE: For AM IF Alignment Use AM Sweep Signal Generator Of 10 KHz Deviation, 60 Hz Modulation For Full Bandpass Display. Bandswitch
In AM. Also Connect Modulation Frequency To Scope Horizontal. (If AM Sweep Not Available, See Steps 8 Through 16.)
1
Short Test Point "L" (AM Gang Antenna Section) To Chassis Ground.
2
Test Point "K"
AM IF Input
47 Ohm in
shunt with
gen. output.
Then from
Scope
Detector
Output
+ 455 KHz
Gang
Closed
Adjust Generator To Center
Frequency Of Ceramic Filter.
3
hot lead a
27 Ohm in
series with
a .01 MF
capacitor.
See Fig. 1.
Across R107
Tune Generator To Center Total Bandpass
Waveform. Do Not Change Generator Frequency
For Remainder Of AM IF Alignment.
4
Center Freq.
Of Ceramic
Filter In T102
Gang
Closed
L103,L104
(T102)
Adjust For Maximum Gain And
Symmetry.
5
T103
Adjust For Maximum.
6
Remove Short Between Test Point "L" And Chassis Ground.
7
Test Point "L"
AM Ant. Input
As Above
Scope
Detector
Output
Center Freq.
Of Ceramic
Filter In T102
Gang
Closed
L102
Adjust For Symmetrical Pattern, With
Maximum Attenuation At IF Center
Frequency.
ALTERNATE METHOD - IF AM SWEEP GENERATOR IS NOT AVAILABLE
NOTE: For AM IF Alignment Use A Signal With 400 Hertz Modulation. Bandswitch In AM.
8 Short Test Point "L" (AM Gang Antenna Section) To Chassis Ground.
9
Test Point "K"
AM IF Input
47 Ohm in
shunt with
gen. output.
Then from
hot lead a
27 Ohm in
series with
a .01 MF
capacitor.
See Fig. 1.
VTVM
Detector
+ 455 KHz
Gang
Closed
■
10
Output
Across R107
Rock Generator While Adjusting
(T102 Primary) For Maximum.
L103
Adjust For Maximum.
11
Rock Generator While Adjusting L104
(T 102 Secondary) For Maximum.
12
Repeat Steps 10 & 11 For Minimum Change.
13
Equal Output Should Be Found If Generator
Is Detuned Equal Frequency Each Side
Maximum.
14
Center Freq.
Of Ceramic
Filter In T102
Gang
Closed
T103
15
Remove Short Between Test Point
M L" And Chassis Ground.
16
Test Point "L"
AM Ant. Input
As Above
VTVM
Detector
Output
Center Freq.
Of Ceramic
Filter In T102
Gang
Closed
L102
Adjust IF Trap For Minimum.
17
One Turn Loosely
Coupled To AM
Wavemagnet
None
1600 KHz
1600 KHz
C103
Set Oscillator to dial scale.
18
600 KHz
600 KHz
T101
19
Antenna
Repeat Steps 17 & 18 for minimum change.
20
1400 KHz
1400 KHz
C1F
Align Antenna stage.
21
600 KHz
600 KHz L101 if necessary
22
Repeat Steps 20 & 21 for minimum change.
NOTE: For FM IF Alignment Use A Signal Of 250 KHz Deviation, 50 Hertz Modulation For Full Bandpass Display. FM In MONO, AFC OFF,
Preset R211 And R302 To Mid Rotation Before Connecting Generator. Connect Generator Cable Ground To Gang Frame.
23
Test Point "D"
FM IF Input
47 Ohm in
shunt with
gen. output.
Then from
hot lead a
27 Ohm in
series with
1 181 MF
capacitor.
See Fig. 1.
Scope
Test Point
"G"
10.7 MHz
Gang
Closed
L201, L202
(T201)
Align I.F. transformer for maximum
output and symmetry as indicated
in Scope Pattern "B".