Sanyo M7790K - SW2 ALIGNMENT; FM ALIGNMENT; FM MPX (Multiplex) ADJUSTMENT

TUNER ADJUSTMENT (continuea)
SW2 eee
bl Alignment
Calibration
of
Tuning Range
Adjustment
of
Tracking
| Connections =
Frequency
Connect AM signal
generator to
antenna terminals
(TP1 and TP2)
through dummy
antenna
(300/10pF).
of Signal
INPUT OUTPUT Generator
Connect VTVM with
3.22 dummy load
and oscilloscope
to Phones/Ext.
Speaker jack.
Setting
23.7MHz High End
8.5MHz 8.5MHz
21.0MHz | 21.0MHz
Repeat the above steps until no further change is noted in any of the adjustments.
FM ALIGNMENT
Alignment
Connections
Obtain sine-wave of 400Hz
and maximum amplitude.
Standard test frequency 400Hz and deviation 22.5kHz
Frequency
INPUT
Place output of
gene-scope to
Calibration Pin 3 of IC1
of through capacitor
IF (10pF).
2
Calibration Connect FM signal
of generator to antenna
Tuning Range
Adjustment
of
Tracking
terminals (TP1 and
TP2) through
dummy antenna
(75Q, unbalanced
type).
of Signal
Generator
OUTPUT
Connect input
Tuning Dial
Setting Adjustments
Turn T2(blue core)
fully counter-
Remarks
Obtain symmetrical curve
and maximum amplitude.
Obtain S curve and
maximum amplitude.
106MHz
terminal of gene- clockwise
scope to detector T1.
output terminals
(CN1-1 and CN1-2, 10.7MHz Low End
or CN1-3).
T2 (blue core)
87.2MHz L2
Connect VTVM with
3.20 dummy load 109.0MHz | HighEnd TC2 (PVC)
and oscilloscope
to Phones/Ext. 9OMHz 90MHz L1
Speaker jack.
106MHz | TC1 (PVC)
Obtain sine-curve and
maximum amplitude.
FM MPX (Multiplex) ADJUSTMENT
Before the adjustment, set the switches as follows:
e@ Function Select Switch
e Band Select Switch
e@ Mode Switch
pape (V.C.0.) ADJUSTMENT
Connect a Frequency counter and a resistor (830k) to the
sixth pin (Test Point TP4) in IC3 (TA7343P) as illustrated.
2. Adjust the potentiometer (P1) until the oscillation frequency
of IC3 becomes 38kHz (+20Hz).
FM
aes ie ee
Ferquency Counter
Repeat the above steps until no further change is noted in any of the adjustments.
38kHz (+20Hz)