5
20MR10
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 PROTECT OR CIRCUIT TEST
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. Receive a good local channel.
4. Connect a
digital
voltmeter
to TP653 and make sure
that the
voltmeter
reads 21.4 ±1.5 V.
5. Apply external 27.2V 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 VOLT AGE 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 a strong air signal or a
properly
tuned in test signal.
3. Enter the service mode and select the
service
adjustment
"S03" and Bus data "01" (Y-mute on).
4. The
voltage
should
be
approximately
26.0kV (at zero
beam).
If a correct reading cannot be obtained, check
circuitry for
malfunctioning
components.
After the
voltage test, make
Y-mute of
f to the normal mode.
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.
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