HITACHI - PLASMA TV _ NO PICTURE _ TROUBLESHOOTING _ MODELS _P42H401, P42H4011, P50H401, P50H4011, P55H4011, P55H401, P42T501, P50S601, P50V701, P50X901, P50T501, P55H401, P55T501 and P60X901 - [2]

                                                                       [2]

PWB CHECK

Look for any burns, open fuses, etc... If burns found, then replace the PWB.

If fuses open, first check for low ohms condition before replacing the fuse an attempting to turn on the set.

VOLTAGE CHECKS:  

When AC applied, then when the Power Button is pressed.

• When AC is first applied, the power supply should turn on and supply the following voltages for a little more than 2 minutes.
• Stand-By voltages (SBY 5V), (SYB 3.3V on some models) and all voltages on the CNPPS connector?  (This requires Power 1 and Power 2 commands being high coming from the Digi-Main PWB CN63). After approx. 2 minutes, (unless Quick Start is on), a relay click is heard and the CNPPS voltages turn off.

If Quick Start is on, the Power 1 and 2 commands remain high and all above voltages remain on.

WHEN POWER BUTTON IS PRESSED

When the power button is pressed, the Logic PWB sends Vsago and Vcego commands to the power supply via the 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 diagnostics is run.
2. If Quick Start is on, the above does not happen because the Power 1 and 2 commands are already high as stated in “When AC is First Applied”.

• Generating the Vs and Va voltages. (This requires the Vcego and Vsago commands being high coming from the Logic PWB CN68 connector).

42"

Va CN64 pin 1

Vs (85V) CN64 pin 7.

-Vs (-85.5) CN64 pin 9. (New for the DW-3 Chassis)

50"

Va (60V) CN64 pin 1

Vs (80V) CN64 pins 8 or 9 or 10.

FOR CONDITIONS 2 and 3 BELOW IN THE DW-3 SERIES:

• Any Time Vs/Va voltages do not appear and a test is made, each time a new test is to be made,
• Press the Power Button and Turn the Plasma OFF.
• Wait until you hear a "Click".
• Unplug the CN68 connector.
• Re-Plug the CN68 connector. If this is not done, the Turn On command for Vs/Va at Pin 7 and 8 of the CN68 connector will not happen.

 If the Connector CN-68 is pulled and voltage readings are taken on the CN68 connector at the Power Supply, the STB 3.3V will be present at pin 3. There will be no voltage at pin 1.

This answer to Are you Generating Vs and Va voltages will be

1. Yes (Green Power LED will be always on)
2. Brief rise the collapse (Green Power LED will go Green then Go Off or may stay Green)
3. No (Green Power LED will go Green then Go Off or may not go Green at all).

If the answer is 1.  Yes (Green Power LED will be always on).

• This indicates providing Vs and Va voltage to the X-SUS and Y-SUS PWBs. Use an Analog Scope.
•  Look at the outputs from the X-SUS and X-BUS.
•  Use the Top Pin of the connector going to the Panel, on either side.  See if there is activity.

                                                           TOP PIN TO PANEL X-BUS PWB: 29V p/p

• No Activity will usually indicate a defective PWB.
• But if no activity is seen, before condemning the PWB, pull the Ribbon cable from that PWB to the Panel and check again.
• If activity returns, this will usually indicate a defective panel.
• Have to pull all Ribbon Connectors before condemning the PWB

If the Panel is defective with this process, in most cases evidence can be seen on the screen.

Example: If the top ribbon cable is pulled, the Top of the screen will be black, but the bottom will have raster.

If the answer is 2:  (Green Power LED will go Green the Go Off) Brief rise then collapse of the Vs and Va voltages.

This indicates a "Load" on the line.

• Pull the CN-64 connector feeding Vs/Va voltages to the X-SUS.
• Take an ohmage reading from the Va and Vs lines on each PWB.

This means you have to read the Connector on the Power Supply and the pulled connector going to the X-SUS.

See if there is a low value. Low value indicates a defective PWB.

• Normal reading should be infinity. (Using the diode mode on the DV/Voltmeter, there will be a brief charge time, then infinity.)
•  In other words, it may appear as a low ohm reading, but should rise to infinity or open.

(Also note, if there is a charge on the line, the meter may show a low. You must Pull the CN68 connector and take a reading again).

The line should now be infinity when reading the Power supply pins for Va and Vs and when reading the connector going to the X-SUS PWB.)

If a Low, on the connector, pull the CN32 Connector. (Bottom right hand plug on the Y-SUS PWB).

AFTER CONNECTOR IS PULLED OUT

• If the low disappears, then the Y-SUS or SDR PWBs are at fault. (See Note 1 below before condemning PWB).
• If the low remains, then the X-SUS PWB is faulty.

Pull all Ribbon connectors going to the Panel on-by-one while reading the Vs/Va pins.

If the low disappears, the panel is defective. (But, check SDR buffers first.)

If the low remains, the Y-SUS and/or SDR PWBs are defective.

If no evidence found:

• Pull the Ribbon cables to the Panel.
• Does Va / Vs voltage stay up?
• Yes: Defective Panel
• No: In this case neither PWB can be confirmed as the fault. Most often it will be the Y-SUS PWB.

 Can  disconnect the SDR Upper or Lower or both from the Y-SUS PWB and test Vs/Va voltages.

They will come on and stay up with these PWBs removed from the Y-SUS PWB.

If the answer is 3:  No Vs/Va activity.

1. This usually indicates either a dead load on the line or no Vsago / Vcego commands from the Logic PWB CN68.
2. Check the Va/Vs turn on commands.
3. The SBY 5V from CN63 pin 1 must be present before Vsago / Vcego lines can function.
4. When the Power Button is pressed, within moments, (Vcc5.1V) should come when the Vcego and Vsago Commands go high

TESTING THE Va/Vs TURN ON COMMANDS:

• Press the Master Power (Vacation) Switch (on the bottom) to remove AC.
• Wait until you hear a "Click".
• Unplug the CN68 connector. Re-Plug the CN68 connector.

If this is not done, the Turn On command Vcego/Vsago at Pins 7 and 8 of the CN68 connector will not happen.

This must be done every time a new check is made on the CN68 connector if Va/Vs voltages did not come up and stay up.

Attach a DC voltmeter to the CN-68 connector Vcego and/or Vsago, (see preceding 4 pages for pin locations).

Press the Vacation Switch to re-apply AC power and wait for about 30 seconds for initialization.

Press the Power Button while watching the voltmeter.

1. Normal: After several seconds, Vcego and Vsago pins should climb to 3.3V.
2. Trouble sensed: After several seconds, Vcego and Vsago pins should climb, then drop quickly to 0.2V.
3. Abnormal: No Activity at all.

In this case will be either 2 or 3 above.

ABNORMAL: No Activity.

• Pull the CN64 Connector.
• Repeat: Testing the Vsago / Vcego Turn On Commands procedure.
• If condition changes to (2) above, then there is a load on the Va/Vs lines.

If the Answer is 2.

•  Follow the procedure for checking Y-SUS and X-SUS and the Panel listed above.