Zenith HF-46 Stereo Receivers Models MC7031, MC7041, MC7051 ...

STEP
CONNECT
GENERATOR
TO
DUMMY
ANTENNA
RF, IF AND MPX ALIGNMENT PROCEDURE
FOR MODEL MC7051 - Cont'd.
CONNECT
VTVM/
SCOPE TO
INPUT
SIGNAL
FREQ.
SET DIAL
TO
ADJUST
PURPOSE
FM ALIGNMENT
Note: For FM IF Alignment Use A Signal Of 250 KHz Deviation, 50 Hertz Modulation For Full Bandpass Display. Bandswitch In FM. Preset R208,
R21 1 And R303 To Mid Rotation Before Connecting Generator. Connect Generator Cable Ground To Gang Frame.
32 Shunt C1B To Ground With A .001 MF Capacitor.
33
34
35
36
37
Test Point "D"
FM IF Input
At High Side
Of C1F
Test Point "A"
FM Antenna Post
(Disconnect Antenna)
Generator
Output
Probe
"A"
Scope
Detector
Probe "C"
Test Point
At IC201
Pin 1.
300 Ohm Scope
Test Point
"H"
10.7 MHz Gang
Closed
Tune Generator To Center Total Bandpass
Waveform. Do Not Change Generator Frequency
For Remainder Of FM IF Alignment.
Center Freq.
Of Ceramic
Filters Y201,
Y202, Y203
Gang
Closed
T1
Align I.F. Transformer For
Maximum Output And Symmetry
As Indicated In Scope Pattern
"A".
98 MHz 98 MHz
R216 Adjust For No Sound Output
When Input Is Below 1.7/iV With
Mute Switch ON.
R215 Adjust For A Reading Of 4 To 5
One Meter M1 02 With Input Of
60dBV (1mV).
NOTE: For FM Detector Alignment Use A Signal Of 75 KHz Deviation, 1 KHz Modulation. Also Connect Generator Modulation Frequency To
Scope Horizontal. Adjust Generator IF Frequency To Center Total Bandpass Waveform. Do Not Change Generator IF Frequency For
Remainder Of IF Alignment. (If Your Generator Does Not Provide Output For Audio Modulation Frequency Use Horizontal Output From
Generator, Or Scope Horizontal Sweep, And Follow Step 38C). Minimum Distortion Can Only Be Achieved By Use Of Step 38A Below.
38
39
Test Point "D"
FM IF
Input
At High Side
Of C1F
Generator
Output
Probe
"A"
A. Distortion
Analyzer
(Thru A 100
Usee Deemphasis
Network)
Probe "B"
And Scope.
B.Scope
C.Scope
Test Point
"H"
Center
Frequency
Of Ceramic
Filters Y201,
Y202, Y203.
Gang
Closed
L204, L205
(T201)
L205
A. Preferred Method: Distortion
Analyzer At Test Point "H"
Should Read Minimum Distortion.
B. Alternate Method: Adjust For
Linear Scope Trace-No Curve At Ends
Of Trace. Disregard Meter Reading.
C. Alternate Method: Adjust For
Maximum Length And Symmetry,
Similar To Scope Pattern "A".
Adjust For Center Reading On
Tuning Meter M101.
40 Test Point "A" 300 Ohm
106 MHz 1 06 MHz C1H Set Oscillator To Dial Scale.
41 FM Antenna Post
42
43
44
45
46
47
(Disconnect Antenna)
48 Audio Osc. — Test Point
"F"
49 Test Point "H"
90 MHz 90 MHz L7
Repeat Steps 40 & 41 For Minimum Change.
106 MHz 1 06 MHz C1D, C1F Align FM Detector Stage For
90 MHz 90 MHz L3, L4
Maximum.
106 MHz 106 MHz C1B Align FM Antenna Stage For
Maximum.
90 MHz 90 MHz L2 If Necessary
Repeat Steps 43 Thru 46 For Minimum Change.
200 KHz
T301 Align For Minimum.
NOTE : Apply Sufficient Signal Level — Approx. 1 00 Microvolts — To Obtain Full Limiting At Point Near 98 MHz.
Frequency Unmodulated
R308 A. Frequency Counter Should
50
Counter And/
Or Scope
RF Carrier
Read 19 KHz, + 100 Hz.
51
52
Test Point
"M"
Scope And/Or
AC VTVM
Left Tape
Output
Right Tape
Output.
NOTE: Do Not Readjust Control R308 After Step 50.
98 MHz
1 0% Pilot
(L+R)
(L-R)
(L Only)
T302
R318
B. Alternate Method: Connect Test
Point "M" Signal To Scope Vertical
And An Accurate 19 KHz Signal
To Scope Horizontal Input. Adjust
For One Square Synchronized
Waveform.
Adjust For Separation.
Maximum Left Output.
— Check For Separation. Minimum
Right Output.
COLOR
CODE
CERAMIC FILTERS
NOMINAL CENTER
FREQUENCY
FREQUENCY
RANGE
Black 10.64 MHz 10.61 to 10.67 MHz
Blue 10.67 MHz 10.64 to 10.70 MHz
Red 10.70 MHz 10.67 to 10.73 MHz
Orange 10.73 MHz 10.70 to 10.76 MHz
White 10.76 MHz 10.73 to 10.79 MHz
15