20AR20/30
INSTALLATION AND SERVICE INSTRUCTIONS
Note: (1) When performing any adjustments to resistor controls and transformers use non-metallic
screwdrivers or TV alignment tools.
(2) Before performing adjustments, the TV set must be on at least 15 minutes.
CIRCUIT PROTECTIONHIGH VOLTAGE CHECK
The receiver is protected by a 3.15A fuse (F701),High voltage is not adjustable but must be checked
mounted on PWB-A, wired into one side of the ACto verify that the receiver is operating within safe
line input.and efficient design limitations as specified checks
should be as follows:
X-RADIATION PROTECTOR CIRCUIT TEST
1. Connect an accurate high voltage meter between
After service has been performed on the horizontalground and anode of picture tube.
deflection system, high voltage system, B+ system,2. Operate receiver for at least 15 minutes at 110~220V
test the X-Radiation protection circuit to ascertainAC line voltage, with a strong air signal or a properly
proper operation as follows:tuned in test signal.
3. Enter the service mode and select the service
1. Apply 220V AC using a variac transformer foradjustment "S19" and Bus data "01" (Y-mute on).
accurate input voltage.4. The voltage should be approximately, 26.5kV (at zero
2. Allow for warm up and adjust all customer controlsbeam).
If a correct reading cannot be obtained, check circuitry
for normal picture and sound.for malfunctioning components. After the voltage test,
3. Receive a good local channel.
4. Connect a digital voltmeter to TP653 and make suremake Y-mute off to the normal mode.
that the voltmeter reads 20.6 ? 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.
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ACEC
