Saturday, August 18, 2012

HITACHI PLASMA TV -TROUBLESHOOTING POWER SUPPLY (2)

Hitachi Plasma TV Power Supply troubleshooting
                                                                        {2}
PWB CHECK
  • Look for any burns, open fuses etc:  
  • If burns found, replace the PCB as card basis.  It in not practical to make a repair to this board.
VOLTAGE CHECK
  • When AC is first applied, the power supply should turn ON and supply the following voltages.
  • Standby voltages [SBY 5V], SBY 3.3V on some models] and all voltages on the CNPSS connector.  
  • This requires Power-1 and Power-2 commands being high coming from the Dig-Main PWB CN-63.  After approx: two minutes, unless quick start is ON, a relay click is heard and the CNPPS voltages turn OFF.
  • If quick start is ON, power 1 & 2 commands remain high and all above voltages remain ON.
WHEN THE POWER BUTTON IS PRESSED:  

When the power button is pressed, the logic PWB sends Vsago and Vcego commands to the power supply; via CN64 connector.
  • There are two conditions the set can be in before the power button is pressed.

  1. If quick start is OFF, the Power-1  and Power-2 commands are output from the Digi-Main PWB after a short internal self diagnosis is run.
  2. If quick start is ON, the above stated does not happen because, Power-1 & 2 commands are already high, 'When AC is first applied'.
  • Generating the Vs and Va voltages?  This requires the  Vcego & Vsago commands being high coming  from the logic PWB CN-68 connector.
For a 42"
  • Va-CN64 pin number-1
  • Vs- [85v] CN64 pin number-7
  • -Vs-[-85.8v] CN 64 pin number 9 (For newer DW-3 chassis)
For a 50"
  • Va-[60V] CN64 pin number-1
  • Vs-[80V] CN64 pins 8/9/10
COMMON CONDITIONS 2&3 BELOW IN THE DW-3 SERIES
  • Any time Vs of Va voltages do not appear and a test is made, each time a new test to be made.
  • Press the Power button and turn the Plasma Off.
  • Wait until a click of relay is heard.
  • Unplug CN64 connector.
  • Re-plug the CN64 connector.  
  • If this is not done, the turn ON command for Vs/Va at pins 7&8 of the CN68 connector will not happen.
  • If the connector CN68 is pulled and voltage readings are taken on the CN68 connector at power supply the STB 3.3V will be present at pin-3.  There will be no voltage at pin-1.
P50H401 POWER SUPPLY REGULATOR BOARD


Continued on next post:

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