This LCD TV will not turn on. When the power switch is pressed, the green LED on the front lights for a few seconds and then turns back off. There is no sound, (snap, crackle, pop, or other) and no picture or light from the screen.
I initially disassembled the entire set to inspect all of the circuit boards (top and bottom) and found no obvious burns, loose connections, pinched wires, or swollen caps. On a hunch, I replaced the main analog board, but that made no difference.
I have downloaded and studied the service manual, but am rather confused as to where exactly some of the voltage measurements are supposed to be taken It appears that the diodes listed in "Power Failure Circuit" all appear to be on the bottom of the circuit boards. Does that mean that I am to remove them from the TV and flip them over to test Voltage? If so, I can...it just seems like they would have listed locations on the top of the circuit boards to test instead.
Thus far, I have determined that I am getting AC in. I confirmed both 5.5 V and 3.3 V STBY power in the jumpers with voltage listed on analog board.
J1634 on the analog board is labeled 12/15V, however, in STBY I measure .04, and when I press the "On" button, this increases to 12V.
Otherwise, I have back probed the plugs and have found the following:
K603 24V on Pin #1, 2, 3, 4
K8FRA Pin #1 = 5.5V, #2 = GND, #3 = 3.54V, #4 =0.48V, #5 = 0.48V, #6 = 0.04V
K8CTRA PIN # 1 = 5.5V, #2 = GND, #3 = 0.11V
K5A #1 = GND, #2 = .04/11.95V (similar to what was at J1634), #3&4 = 5.05V
#12 = 3.3V
The schematic shows #7 as 9V, but I am only getting 0.11V off of it.
So my questions are, do any of these measurement help localize where the problem is? If not, can anyone suggest where to focus next?
Only one of the diodes listed in the power failure circuit appears to be on the digital board, so I guess I can try to test that diode to see if it appears to be open or not. The others are all on the Main Analog board so, I am suspecting since nothing changed when that was switched out, that those are not bad.
However, I am just not certain that one of the other components might not be triggering the fault/failure to start condition.
I initially disassembled the entire set to inspect all of the circuit boards (top and bottom) and found no obvious burns, loose connections, pinched wires, or swollen caps. On a hunch, I replaced the main analog board, but that made no difference.
I have downloaded and studied the service manual, but am rather confused as to where exactly some of the voltage measurements are supposed to be taken It appears that the diodes listed in "Power Failure Circuit" all appear to be on the bottom of the circuit boards. Does that mean that I am to remove them from the TV and flip them over to test Voltage? If so, I can...it just seems like they would have listed locations on the top of the circuit boards to test instead.
Thus far, I have determined that I am getting AC in. I confirmed both 5.5 V and 3.3 V STBY power in the jumpers with voltage listed on analog board.
J1634 on the analog board is labeled 12/15V, however, in STBY I measure .04, and when I press the "On" button, this increases to 12V.
Otherwise, I have back probed the plugs and have found the following:
K603 24V on Pin #1, 2, 3, 4
K8FRA Pin #1 = 5.5V, #2 = GND, #3 = 3.54V, #4 =0.48V, #5 = 0.48V, #6 = 0.04V
K8CTRA PIN # 1 = 5.5V, #2 = GND, #3 = 0.11V
K5A #1 = GND, #2 = .04/11.95V (similar to what was at J1634), #3&4 = 5.05V
#12 = 3.3V
The schematic shows #7 as 9V, but I am only getting 0.11V off of it.
So my questions are, do any of these measurement help localize where the problem is? If not, can anyone suggest where to focus next?
Only one of the diodes listed in the power failure circuit appears to be on the digital board, so I guess I can try to test that diode to see if it appears to be open or not. The others are all on the Main Analog board so, I am suspecting since nothing changed when that was switched out, that those are not bad.
However, I am just not certain that one of the other components might not be triggering the fault/failure to start condition.
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