Installation And Service Instructions - Sharp 21MJ50 Service Manual

INSTALLATION AND SERVICE INSTRUCTIONS

Note: (1) When performing any adjustments to resistor controls and transformers use non-metallic
screwdriver or TV alignment tools.
(2) Before performing adjustment, TV set must be on at least 15 minutes.
CIRCUIT PROTECTION
The receiver is protected by a 4.0A fuse (F701),
mounted on PWB-A, wired into one side of the AC
line input.
X-RADIATION PROTECTOR CIRCUIT
TEST
1. After service has been performed on the
horizontal deflection system, high voltage
system, B + system, test the X-Radiation
protection circuit to ascertain proper operation
as follows:
1) Apply 120V AC using a variac transformer for
accurate input voltage.
2) Allow for warm up and adjust all customer controls
for normal picture and sound.
3) Select a local channel.
4) Connect a digital voltmeter to TP653 and make sure
that the voltmeter reads 21.5±1.5V.
5) Apply external 26.8V DC at TP653 by using an
external DC supply, TV must be shut off.
6) To reset the protector, unplug the AC cord and make
a short circuit between TP651 and TP652.Now make
sure that normal picture appears on the screen.
7) If the operation of the horizontal oscillator does not
stop in step 5, the circuit must be repaired before the
set is returned to the customer.
HIGH VOLTAGE CHECK
High voltage is not adjustable but must be checked
to verify that the receiver is operating within safe
and efficient design limitations as specified checks
should be as follows:
1. Connect an accurate high voltage meter between
ground and anode of picture tube.
2. Operate receiver for at least 15 minutes at 120V AC
line voltage, with strong air signal or properly tuned
in test signal.
3. Set service mode on (See next page.),Service
No.S19 and Bus data "01" (Y-mute on).
4. The voltage should be approximately 26.5kV (at zero
beam).
If a correct reading cannot be obtained, check circuitry
for malfunctioning components. After the voltage
test,make Y-mute off (normal mode).
7
20J-S100/100S
CJ20S10/21MJ50