Zenith HF-46 Stereo Receivers Models MC7031, MC7041, MC7051 ...
Zenith HF-46 Stereo Receivers Models MC7031, MC7041, MC7051 ...
Zenith HF-46 Stereo Receivers Models MC7031, MC7041, MC7051 ...
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RF, IF, MPX AND AUDIO ALIGNMENT PROCEDURE<br />
FOR MODELS <strong>MC7031</strong>, <strong>MC7041</strong> - Cont'd.<br />
STEP<br />
CONNECT<br />
GENERATOR<br />
TO<br />
DUMMY<br />
ANTENNA<br />
CONNECT<br />
VTVM/<br />
SCOPE TO<br />
INPUT<br />
SIGNAL<br />
FREQ.<br />
SET DIAL<br />
TO<br />
ADJUST<br />
PURPOSE<br />
36<br />
Test Point "A"<br />
FM Antenna Post<br />
(Disconnect Antenna)<br />
300 Ohm + 98 MHz 98 MHz<br />
R211<br />
(Mute)<br />
Adjust For No Sound Output<br />
When Input Is Below 1.7/xV<br />
With Mute Switch ON.<br />
37<br />
R208<br />
(Meter)<br />
Adjust For A Reading Of 6 On<br />
Meter M102 With 60 dbV (1mV)<br />
Input.<br />
NOTE:<br />
For FM Detector Alignment Use A Signal Of 75 KHz Deviation, 1 KHz Modulation. Also Connect Generator Modulation Frequency To<br />
Scope Horizontal. Adjust Generator IF Frequency To Center Total Bandpass Waveform. Do Not Change Generator IF Frequency For<br />
Remainder Of IF Alignment. (If Your Generator Does Not Provide Output For Audio Modulation Frequency Use Horizontal Output<br />
From Generator, Or Scope Horizontal Sweep, And Follow Step 38C.) Minimum Distortion Can Only Be Achieved By Use Of Step 38A<br />
Below.<br />
38<br />
Test Point "D"<br />
FM IF Input<br />
At Q2 Base<br />
Generator<br />
Output<br />
Probe "A"<br />
A. Distortion<br />
Analyzer<br />
(Thru a 100<br />
Usee Deemphasis<br />
Network<br />
Probe "B"<br />
And Scope.<br />
Center<br />
Frequency<br />
Of Ceramic<br />
Filters Y201,<br />
Y202, Y203.<br />
Gang<br />
Closed<br />
L205, L206<br />
(T202)<br />
A. Preferred Method: Distortion<br />
Analyzer At Test Point "H"<br />
Should Read Minimum Distortion.<br />
B. Scope<br />
B. Alternate Method: Adjust For<br />
Linear Scope Trace - No Curve At<br />
Ends Of Trace. Disregard Meter<br />
Reading.<br />
C. Scope<br />
C. Alternate Method: Adjust For<br />
Maximum Length And Symmetry,<br />
Similar To Scope Pattern "B".<br />
39<br />
Test Point<br />
"H"<br />
L205<br />
(T202)<br />
Adjust For Center Reading On<br />
Tuning Meter M101.<br />
40 Test Point "A"<br />
41<br />
FM Antenna Post<br />
(Disconnect Antenna)<br />
42<br />
43<br />
44<br />
45<br />
<strong>46</strong><br />
47<br />
300 Ohm<br />
106 MHz 106 MHz C1E Set Oscillator To Dial Scale.<br />
90 MHz 90 MHz L4<br />
Repeat Steps 40 & 41 For Minimum Change.<br />
106 MHz 106 MHz C1C Align FM Detector Stage For<br />
90 MHz 90 MHz L2 If Necessary<br />
Maximum.<br />
106 MHz 106 MHz C1 A Align FM Antenna Stage For<br />
90 MHz 90 MHz L1<br />
Maximum.<br />
Repeat Steps 43 Thru <strong>46</strong> For Minimum Change.<br />
NOTE:<br />
Apply Sufficient Signal Level — Approx. 100 Microvolts — To Obtain Full Limiting At Point Near 98 MHz.<br />
48 Frequency<br />
Counter And/<br />
or Scope<br />
Test Point<br />
"M"<br />
Unmodulated<br />
R F Carrier<br />
R303<br />
(VCO)<br />
A. Frequency Counter Should Read<br />
19 KHz, +100 Hz.<br />
B. Alternate Method: Connect Test<br />
Point "M" Signal To Scope Vertical<br />
And An Accurate 19 KHz Signal To<br />
Scope Horizontal Input. Adjust For<br />
One Square Synchronized Waveform.<br />
49<br />
Scope And/Or<br />
AC VTVM<br />
Left Tape<br />
Output<br />
98 MHz<br />
10% Pilot<br />
(L + R) (L - R)<br />
(L Only)<br />
R313<br />
Adjust For Separation. Maximum<br />
Left Output.<br />
50<br />
Right Tape<br />
Output.<br />
Check For Separation. Minimum<br />
Right Output.<br />
NOTE: Do Not Readjust Control R303 After Step 48.<br />
COLOR<br />
CODE<br />
CERAMIC FILTERS<br />
NOMINAL CENTER<br />
FREQUENCY<br />
FREQUENCY<br />
RANGE<br />
Black 10.64 MHz 10.61 to 10.67 MHz<br />
Blue 10.67 MHz 10.64 to 10.70 MHz<br />
Red 10.70 MHz 10.67 to 10.73 MHz<br />
Orange 10.73 MHz 10.70 to 10.76 MHz<br />
White 10.76 MHz 10.73 to 10.79 MHz<br />
13