Sharp 25VT-CJ10, Service Manual

Page: 12 / 56

25VT-J100
25VT-CJ10
12
INSTALLATION AND SERVICE INSTRUCTIONS
Notes: (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 CIR-
CUIT TEST
After service has been performed on the horizontal
deflection system, high voltage system, or B+ system,
test the X-radiation protector 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 using the remote controller,
set the brightness level and contrast level to
maximum.
3. Check the voltage of test point TP653. (It’s voltage
should be about 10.3V DC.)
4. Apply external 13.3V DC at TP653 by using an
external DC supply, The increased voltage will cause
the horizontal oscillator to stop and the TV to shut
off.
5. To re-start the osillator, remove the external DC
power supply and short together TP651 and TP652.
Once the TV set operates normally again, remove
the short between TP651 and TP652.
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.
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 to Service mode on, service item: MUTE, and
bus data 1(Y-mute on).
4. The voltage should be approximately 28.1kV (at zero
beam).
If a correct reading cannot be obtained, check
circuitry for malfunctioning components.
Upon completion of voltage check, readjust screen
control for proper operation and set S851 to center
position (cut off mode).