Sharp CX51N3, Service Manual

7

7-1

7-2

CX51N3/N4

PIF ADJUSTMENT

NO. Adjustment part

Adjusting procedure and conditions

Waveform and others

1

Fig. 1

2

RF-AGC
TAKE OVER
POINT
ADJUSTMENT
(I

2

C BUS

CONTROL)

1. Receive "PAL COLOUR BAR" signal.

» 

Signal Strength: 57 

±

1 dB

µ

V (75 ohm open)

2. Connect the oscilloscope to TP201 (Tuner’s

AGC Terminal) as shown in Fig. 3.

3. Call "AGC" mode in service mode. Adjust the

"AGC" bus data to obtain the Tuner output pin
drop 0.1 V below maximum voltage.

4. C h a n g e   t h e   a n t e n n a   i n p u t   s i g n a l   t o

63~67dB

µ

V, and make sure there is no noise.

5. Turn up the input signal to 90~95 dB

µ

V to be

sure that there is no cross modulation beat.

Note:

For the 50 ohm signal strength
gauge, when not using 50/75
impedance adapter, signal
strength is 52 

±

1 dB

µ

V(75 ohm

open), instead of 57 

±

1 dB

µ

V

(75 ohm open).

Precaution:

The loss of using impedance
adapter

»

 Bias box: About 4.5 V

Oscilloscope

0.1V

TV Set

Bias box

TP201

+

+

–

–

Tuner IFT
(PRESET)

1. Get the tuner ready to receive the E-9 CH

signal, but with no signal input.
Adjust the PLL data.

2. Connect the sweep generator's output cable

to the tuner antenna. (RF SWEEP)

3. Adjust the sweep generator's to 80dBuV.
4. Connect the response lead (use LOW IMPED-

ANCE probe with wave detector; see Fig.1) to
the tuner's IF output terminal. (This terminal
must have the probe alone connected).

5. Set the RF AGC to 0 - 6 V with no saturation

with the waveform.

6. Adjust the tuner IF coil to obtain the waveform

as shown in Fig. 2.

Note: Be  sure to keep the tuner cover in

position during this adjustment.

E-9 CH

P

                C

10k

100k

1n60

75ohm

IF OUT

-1.5+/-0.8dB

1000p

Oscilloscope

Fig. 2

Fig. 3

PURITY ADJUSTMENT

NO. Adjustment part

Adjusting procedure and conditions

Waveform and others

1

PURITY ADJ.

1. Receive the GREEN-ONLY signal. Adjust the

beam current to ~ 700 

µ

A

2. Degauss the CRT enough with the degausing

coil.

3. Maintain the purity magnet at the zero mag-

netic field and keep the static convergence
roughly adjusted.

4. Observe the points a, b, as shown in Fig. 1-1

through the microscope. Adjust the landings
to A rank requirement.

5. Orient the raster rotation to 0 eastward.
6. Tighten up the deflection coil screws.

»

 Tightening torque: 108N 

±

 20 N

(11kgf 

±

 2 kgf)

7. Make sure the CRT corners landing meet the

A rank requirements. If not, stick the magnet
sheet to correct it.

    Note:This adjustment must be done after

warming up the unit for 30 minutes or
longer with a beam current over 700 

µ

A.

* For the following colours press R/C RGB key to

change.

* Press R/C RGB key for 1 sec-

ond in NORMAL MODE, the col-
our will change to RGB mono
colour mode.

a

b

A

B

A

B

A = B

A = B

Rank "A" 

(on the right of the CRT)

Rank "A"

(on the left of the CRT)

Green-only

Blue-only

Red-only

Signal-colour

screen cleared

Fig. 1-1

Fig. 1-2

Fig. 1-3

ADJUSTMENT PRECAUTION: Make sure TV Set in "Nomal Condition" before switch to Service Mode for Adjustment.