Question about Hitachi 53UDX10B 53" Rear Projection Television
When i press the button to turn tv on, it won't zap on. When i unplug tv, and then plug it back in. I see a few green light zap on in the back, but they then zap off a few minutes later. Also the red button in the front, turns on for a second but then is gone.
This does have power supply board but if you see lights (green) the power supply CIRCUIT BOARD IS OKAY. Ifyou want to attempt to repair your self try this if NOT call An Authorized Service Center & have them give a written estimate B4, avg. cost $550.00:
This power supply runs all the time when the AC is applied. The use of the power supply creating Stand By Voltage supplies eliminates the need for a Stand-By transformer. The following explanation will describe the Turning ON and OFF of the projection television.
The Microprocessor I001 generates the ON-OFF control signal from pin (53). The logic states of this pin are High = On and Low = Off. When the set is turned On, the high from pin (53) is routed to the Relay Drivers Q003 and Q004. This turns on Q003 and it’s collector goes low which turns off Q004 and it’s collector goes High.
This On/Off from the Relay Drivers will perform the following :
Turns on the Shut Down “Power Shorted” detection circuit, Q917 and Q919.
Turns on the Relay S901 through Q914 providing AC to the Deflection Power Supply on the Power/Deflection PWB.
SOME SHUT-DOWN DETECTION CIRCUITS SHUT OFF DURING STAND-BY: (See Figure 1)
During Stand-By, some of the secondary voltages produced are turned off, except the STBY voltages after regulation. This could cause a potential problem with the Short Detection circuits for shutdown. To avoid accidental shut down, Q917 also controls the activity of Q919. During Stand-By, the output from the Microprocessor On/Off pin (53) is Low. This Low is inverted by Q003 and inverted again by Q004 and this Low is routed to the base of Q917 turning it Off. This turns off Q917 because it’s base is pulled Low through D927. This action turns off Q917. When Q917 is off, it doesn’t supply emitter voltage to the Emitter of Q919. The base of Q919 is connected to 3 Low Detection inputs from [PROTECT 1], (See the Sub Power Supply Shut Down Circuit explanation and diagram for further details).
PROTECT 1 monitors IC02, 3 & 4 on the Signal PWB. IC02 produces 5.5V, IC03 produces 3.3V, and IC04 produces 2.2V.
NOTE: PROTECT 1 will never go below 2.2 V, unless the 2.2V line is shorted.
NOTE: If the 5.5V or the 3.3V regulator OPENS, the set will not go into shut down, they must have a short to produce a shut down input on PROTECT 1.
The set will shut down after the Screens go excessively bright, but this is from the 115V over current sensor, not PROTECT 1.
When the power supply is in Stand By, the Short Detection circuit could activate. By turning off Q919, no accidental shut down operation can occur.
Good Luck, big IRISH.
Posted on Sep 08, 2008
Need to replace the power supply
Posted on Sep 03, 2008
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