Sharp VT-3448X, Руководство по обслуживанию

Страница: 12 / 144

SERVICE ADJUSTMENT
n
ADJUSTMENT
TUNER
: (preset)
Get the tuner ready to receive the signal,
but with no signal input. Adjust the data.
Connect the sweep generator’s output cable to
the tuner antenna. (RF sweep)
Adjust the sweep generator’s output level to
Connect the response lead (use a low-impedance
probe with wave detector; see
to the
IF output terminal.
I F-OUT
1
1
(This terminal must have the probe alone con-
nected.)
Fig.
Set the RF voltage to with no
tact with the waveform.
Adjust the tuner IF coil to obtain the waveform as
shown in Fig.
Note : Be sure to keep the tuner cover in posi-
tion during this adjustment.
and AFT ADJUSTMENT : (AFT)
coil
Disconnect the antenna from the tuner antenna
terminal.
Apply DC voltage to pin (IF
of
l
DC voltage: V
Fig. 2
Using a digital voltmeter, measure the DC volt-
age at pin of
l
(The digital voltmeter must be able to take
readings down to the third decimal place.)
at V
Relieve of the DC voltage.
Reconnect the antenna in position and receive
the signal.
l
(With the AFT off, adjust the receiving fre-
quency to MHz.)
DC voltage at
- - - - - -
Connect the DC digital voltmeter to
Adjust so that the voltmeter should read
the same voltage as in Step
l
Allowable error: V
AFT coil
Receive the E-l signal in the same condi-
tion as in Step above.
DOWN A B
c UP
Fig. 3
Connect the oscilloscope to pin 1 (AFT,
of
Adjust so that the DC voltage reading be
l
(from the V variable range)