Hitachi 55in plasma TV, model 55HDS69. It will not power up from either the remote or the on/off switch on the side. The TV was used a lot, for more than 5 years. It shut off while running. The red standby light will turn on/off with the main switch underneath. When I first plug in the power cord, all 5 LEDs on the back (near the bottom of the TV) turn on for 1-2 seconds, then all turn off. I do not measure the 90V at the output of the power board, but I measure high voltage in the middle of the board, indicating that an input component is not open. I can also measure a 5.7V at a couple of places on the power board. I tried ordering a replacement power board HA01751 and it didn't make any improvement. I have a copy of the service manual, but don't see any trouble-shotting information for this failure. I have tried unplugging/replugging in the TV many times.

The LEDs all briefly turn on when I first plug the TV in, then turn off and stay off after that. All the voltages seem to measure essentially 0V (Does it matter that I unplugged the cable with the 60V and 80V signals?). However, I measure 339Vdc in the middle of the power board on some of the components. The LEDs all briefly turn on when I first plug the TV in, then turn off and stay off after that. All the voltages seem to measure essentially 0V (Does it matter that I unplugged the cable with the 60V and 80V signals?). However, I measure 339Vdc in the middle of the power board on some of the components.

OK sir please try to disconnect all output connectors only remains ac input then try to power ON...To determine if your power supply is logic switch type or not..If you measure 0v on all while the connectors is unplug (output) your power supply is logic type switch..If that's the case the possible problem is main board because the power board needs a logic signal from the main board to switch it and to release a output voltage to supply all boards..

You measure 399v. right? that voltage is a stock due to standby signal comes from main board that voltage is usually found on the chopper..

I suggest to replace the main board..to easily found the main board online please find the part # of that board (it is usually printed on sticker with combination of letters and numbers).. OK sir please try to disconnect all output connectors only remains ac input then try to power ON...To determine if your power supply is logic switch type or not..If you measure 0v on all while the connectors is unplug (output) your power supply is logic type switch..If that's the case the possible problem is main board because the power board needs a logic signal from the main board to switch it and to release a output voltage to supply all boards.. You measure 399v. right? that voltage is a stock due to standby signal comes from main board that voltage is usually found on the chopper.. I suggest to replace the main board..to easily found the main board online please find the part # of that board (it is usually printed on sticker with combination of letters and numbers)..

With all cables but the 120V disconnected, the input relay on the power board does not close. I was able to measure a 5.7V at a diode on the power board in the lower right corner, under the heatsink with 5V on it. With all cables but the 120V disconnected, the input relay on the power board does not close. I was able to measure a 5.7V at a diode on the power board in the lower right corner, under the heatsink with 5V on it.

OK sir that means the power supply is not logically switch..

If no lit on the 5 LED (knight rider) it means your main board is good..

The possible problems is one of the PDP module such as logic control,y and x sustain..

try to unplug the y sustain input voltage only..then power ON let me know what happen..

also do this on x sustain but the y sustain is connected only x sustain unplug..see what happen..

if the same symptoms after you do that try to replace the logic board.. OK sir that means the power supply is not logically switch.. If no lit on the 5 LED (knight rider) it means your main board is good.. The possible problems is one of the PDP module such as logic control,y and x sustain.. try to unplug the y sustain input voltage only..then power ON let me know what happen.. also do this on x sustain but the y sustain is connected only x sustain unplug..see what happen.. if the same symptoms after you do that try to replace the logic board..

When you say disconnect just the input voltage, do you mean just the 80V, or both the 60V and 80V? When you say disconnect just the input voltage, do you mean just the 80V, or both the 60V and 80V?

disconnect the input connector on the y sustain board exactly..

it have 6 pins and color white connector near the 2 small transformer..just unplug it and read the output on the power board if there's any change.. disconnect the input connector on the y sustain board exactly.. it have 6 pins and color white connector near the 2 small transformer..just unplug it and read the output on the power board if there's any change..

Here is some more information:
On Power Board CN63
Pin 1 = 5.4V
Pin 2 = 0
Pin 3 = 3.3V
Pin 4 = 0.1V
Pin 5 = 3.3V * (labeled as 3.8V)
Pin 6 = 5.3V
Pin 7 = 3.3V
Pin 8 = 0V * (labeled as 3.3V)
On Power Board CN64
Pins 1-2 = 0V * (labeled as 60V)
Pins 3-4 = 0V * (labeled as 5.1V)
Pins 5-7 = 0V
Pins 8-10 = 0V * (labeled as 80V)
On Power Board CN68
Pins 2-3 = 0V * (labeled as 3.1V)
Pin 4 = 0V * (labeled as 2.2V)
Pin 5 = 0V * (1.6V)
Pins 6-8 = 0V
Pin 9 = 3.3V
Pins 10-11 = 0V * (5.1V)
On Power Board CNPPS
Pins 1-3 = 5.7V
Pins 4-6 = 0V
Pin 7 = 10.8V
Pin 8 = 0V
Pin 9 = 17V
Pins 10-12 = 0V
Pins 13-15 = 10.9V * (12V) Here is some more information: On Power Board CN63 Pin 1 = 5.4V Pin 2 = 0 Pin 3 = 3.3V Pin 4 = 0.1V Pin 5 = 3.3V * (labeled as 3.8V) Pin 6 = 5.3V Pin 7 = 3.3V Pin 8 = 0V * (labeled as 3.3V) On Power Board CN64 Pins 1-2 = 0V * (labeled as 60V) Pins 3-4 = 0V * (labeled as 5.1V) Pins 5-7 = 0V Pins 8-10 = 0V * (labeled as 80V) On Power Board CN68 Pins 2-3 = 0V * (labeled as 3.1V) Pin 4 = 0V * (labeled as 2.2V) Pin 5 = 0V * (1.6V) Pins 6-8 = 0V Pin 9 = 3.3V Pins 10-11 = 0V * (5.1V) On Power Board CNPPS Pins 1-3 = 5.7V Pins 4-6 = 0V Pin 7 = 10.8V Pin 8 = 0V Pin 9 = 17V Pins 10-12 = 0V Pins 13-15 = 10.9V * (12V)

I unplugged the 6-posn Y-SUS connector CN31. It didn't make any difference to the 60V and 80V signals. I also unplugged the connector on the power board CN64, and still didn't measure any voltage at the 60V or 80V locations. I unplugged the 6-posn Y-SUS connector CN31. It didn't make any difference to the 60V and 80V signals. I also unplugged the connector on the power board CN64, and still didn't measure any voltage at the 60V or 80V locations.

sir I have a request can try to install again the old power board and see the voltages is still the same while the CN64 is unplug..For me to know if the power board you order is in good condition...

Thanks for the voltages info that was very helpful..

just keep on touch sir sir I have a request can try to install again the old power board and see the voltages is still the same while the CN64 is unplug..For me to know if the power board you order is in good condition... Thanks for the voltages info that was very helpful.. just keep on touch sir