PANASONIC PT-51DX80A
Manual de Servicio

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 (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 counterclockwise to remove Anode lead 3 Discharge to CRT Chassis 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 D-Board

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DVM Figure 4. DVM connected to D-Board. 5. Connect the 8 ~ 15 V DC variable power supply to (+) TP10 and (-) TPGND1, on B-Board. Procedures: 1. Apply a monoscope pattern. 2. Adjust the Picture or Brightness controls so that the DVM reads 16.5 volts ± 0.5 volts. 3. Increase the variable power supply until set turns off. The set should turn off at 16.5 volts ± 0.5 volts (DVM) and high voltage less than 35.5kV. 4. If the DVM reading is other than 16.5 volt (± 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.

FBT Distributor 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.

CRT Protect Circuit

(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)
FTB Distributor

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 and select an active channel. 2. Adjust Brightness and Picture controls for a visible picture. 3. On A-Board momentarily connect a short-jumper from TP095 to GND. The CRT should blank and set turns off. If this does not occur, repair must be performed before returning PTV to customer. 4. Remove short-jumper. 5. Confirm that the TV turns on.

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CRT CHASSIS

H.V. METER

Figure 3. Measuring H.V.

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Service Manual