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Service Manual
Important safety tests
Measuring H.V.
The anode caps are cemented to the CRTs. To gain
access for high voltage measurement, remove the red
CRT’s anode lead from the flyback transformer
distributor. Grasp the anode lead protective cap at its
bottom and squeeze it against the locking cap body
inside, rotate 1/4 turn counter clockwise and pull the
anode lead sleeve out of the FBT distributor. Connect a
high voltage lead (+) from your H.V. meter to the FBT
distributor, and the common (-) to cold ground (
).
(see figure 2).
Note:
Reinsert
the
anode
lead
into
the
FBT
distributor until it is tightly and fully seated.
Turn the locking cap clockwise to lock in place.
(EHT) Protector operation check
With the cabinet back removed, apply a nominal 120V
AC to the PTV.
Over voltage test
Preparation:
1.
Turn PTV “OFF”
2.
Connect
a
NTSC
signal
generator
to
the
antenna terminal.
3.
Connect DVM (+) TPD50 and (-) TPD51 on
D Board (see figure 4)
Figure 3. Measuring H.V.
4.
Connect a H.V. meter (static type, class 0.1) with
high voltage leads to high voltage distributor
on FBT. (See figure 4)
Figure 4. DVM & power supply connection.
5.
Connect the 15 ~ 25 V DC variable power supply to
(+) TPD8 or IC802 pin 2 (D-Board) and (-) heat
sink of Q551 (see figure 4).
Procedures:
1.
Apply a NTSC white pattern.
2.
Turn PTV ON.
3.
Adjust the picture or brightness controls so that the
DVM reads 12.4 volts ± 0.4 volts.
4.
Increase the variable power supply until set turns
off. The set should turn off at 12.4 volts ± 0.4 volts
(DVM) and high voltage less than 36.4kV.
5.
If the DVM reading is other than 12.4 volts (± 0.4
volts), readjust picture or brightness control and
repeat steps 3.
6.
Turn off the variable supply and confirm that the set
will turn on with the remote control.
Figure 2. Removal of FBT leads
FBT distributor
Anode lead
Grasp protective
rubber cap
Push & rotate
cap counter-
clockwise
to remove
Discharge to
CRT chassis
3
1
2
-
+
H.V. METER
FBT Distributor
CRT
CHASSIS
Cold ground
-
+
DVM
TPD51 TPD50
D-Board
Variable
power
supply
(15~25DC)
(+)
(-)
IC802 PIN 2
HEAT SINK OF Q551
MA150
D-Board
100
Ω
1/2 W
OR TPD8
