Sharp WQ-T281Z - Page 7

WO-T2812
WQ-T2812
CIRCUIT
ADJUSTMENT
(TUNER
SECTION)
AM IF/RF ADJUSTMENT
SWITCH Volume Control: Maximum
POSITION Function Selector: Radio
SIGNAL 400 Hz, 30%, AM modulated
GENERATOR
AD-
POINTER | JUST-
SETTING | MENT
TEST FRE-
STEP! staGce | QUENCY
AM IF
requency curve.
AM RF
Lowest
L10
Band frequency
2
coverage
3 1,650 kHz Patti TC8 | Adjust for maximal
ae Oey output.
Repeat steps 2 and 3 until no further improvement can be
made.
cs 7 600 kHz | 600 kHz Adjust for maximal
Tracking BtGut
| 6 1,400 kHz| 1,400 kHz pus:
Repeat steps 5 and 6 until no further improvement can be:
made.
SW1 RF
re 2.25 MHz Pils. Lg
Band qu y Adjust for maximal
coverage output.
requency
= Repeat steps 8 and 9 until no further improvement can be
made.
26mne | 26Mne
Tracking
6.0 MHz | 6.0 MHz
13
Repeat steps 11 and 12 until no further improvement can be
made.
510 kHz
Adjust for maximal
Output.
SW2 RF
Band q y
coverage ;
requency
Repeat steps 14 and 15 until no further improvement can be
made.
i
Tracking
icine
acacia
Adjust
for
maximal
18
19
MHz
19
MHz
output.
i Repeat steps 17 and 18 until no further improvement can be
made.
Adjust for maximal
output.
Oscilloscope
Sweep
Test
IC2
Generator
Loop
Bar
Antenna
Figure 9-1 AM IF
455 kHz
Figure 9-2 AM IF CURVE
Electronic
Voltmeter
Signal Test
Generator Loop a
Bar Antenna
Figure 9-3 AM RF
Electronic
Voltmeter
Signal
Generator
Rod Antenna
SW1/SW2 Dummy
Figure 9—4 SW:/SW.2 RF
¢e To Rod Antenna
R =30 ohm
Z=50 ee 249 PE
Z: Output impedance of signal generator
To Chassis GND
Figure 9—5 SW:/SW2 DUMMY
FM IF/RF ADJUSTMENT
Function Selector: Radio
SEI TION Band Selector: FM Mode Selector: Stereo
Volume Control: Maximum
SIGNAL
GENERATOR
|
400
Hz.
30%,
FM
modulated
ane
au
Fey
SOINTER
doer.
SETTING
|
MENT
1. Using a minus
driver, turn the
core of T2
IF T1 counterclockwise
diok before taking it
10.7 MHz frenuane out of the bobbin.
¥ 2. Adjust for best
“1TF’ curve.
curve. .
Repeat steps 1 and 2 until no further improvement can be
made.
Band q y Adjust for maximal
coverage output.
frequency
Repeat steps 4 and 5 until no further improvement can be
made.
Tracking
108 MHz | 108 MHz
9 Repeat steps 7 and 8 until no further improvement can be
made.
ue
w N m
<0
Adjust for maximal
output.
VCO FREQUENCY ADJUSTMENT
ilar
400
Hz,
30%,
FM
modulated
(mono
signal
DIAL
POINTER
SETTING
ADJUST-
MENT
FREQUENCY REMARKS
FM mono position FM stereo position (unmodulated)
Adjust for 38 kHz
+ 100 Hz.
i es | FE
L7
Figure 10—7 ADJUSTMENT POINTS
—10—
10.7 MHz Oscilloscope
FM Sweep
Generator
iC1
Figure 10—1 FM IF
vr
10.7 MHz
| : 10.7 MHz
Figure 10—2 FM IF CURVE Figure 10—3 FM S CURVE
Electronic
FM
Signal
C3
Voltmeter
Generator Rod Antenna Ga) Pin
FM Dummy
Figure 10—4 FM RF
IC3
FM
Signal
(6)
Pin
Frequency
Generator
1000 pF Counter
Figure 10—5 VCO FREQUENCY
R1
To Rod Antenna
YS)
eee
To Chassis Ground
R1= 37.5 ohms
Z = 75 0hms <9 2 IS ohne
7 R1= 50 o0hms
Z = 50 ohms ee = 50 ohms:
Z: Output impedance of signal generator
Figure 10—6 FM DUMMY