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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 (FBT)
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).
1
Grasp protective
rubber cap
2
Squeeze & rotate
cap counter-
clockwise
to remove
Figure 2. Removal of FBT leads
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 an NTSC signal generator to the
antenna terminal.
3. Connect DVM (+) TPD4 and (-) TPD5 on D-Board.
(See Figure 3)
-
+
H.V. METER
Figure 3. Measuring H.V.
Important Safety Tests
).
Anode lead
3
Discharge to
CRT Chassis
FBT Distributor
FTB Distributor
CRT
CHASSIS
- 3 -
4. Connect a H.V. meter (static type, class 0.1) with
high voltage leads to high voltage distributor
on FBT. (See Figure 4)
TPD5 TPD4
-
+
DVM
Figure 4. DVM connected to D-Board.
5. Connect the 8 ~ 15 V DC variable power supply to
(+) TPB10 and (-) TPBGND, on B-Board.
Procedures:
1. Apply a monoscope pattern.
2. Adjust the Picture or Brightness controls so that the
DVM reads 17.5 volts ± 0.5 volts.
3. Increase the variable power supply until set turns
off. The set should turn off at 17.5 volts ± 0.5 volts
(DVM) and high voltage less than 35.5kV.
4. If the DVM reading is other than 17.5volt (± 0.5
volts), repeat steps 2 and 3.
5. Turn off the variable supply and confirm that the set
will turn on with the Remote Control.
CRT Protect Circuit
This circuit blanks the CRT in the event that there is a
loss of vertical sweep. The circuit is not adjustable;
however the circuit should be checked each time
service is performed.
To check circuit:
1. Turn the PTV On an select an active channel.
2. Adjust Brightness and Picture controls for a visible
picture.
3. On D-Board momentarily connect a short-jumper
from TPD2 to TPDGND. The CRT should blank. If
this does not occur, repair must be performed
before returning PTV to customer.
4. Remove short-jumper.
D-Board
Service Manual
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