TV won't come on.
Is the red light on? Does it change to blue when you press the power button?
If the red light is lit, part of the power supply is working to provide the standby voltage. If it is not lit at all, check to make sure power cord from the mains power (wall outlet) cord is securly and fully inserted in the back of the set. If it still remains dark, the power supply is the primary suspect.
If no light, initially check the fuse, it is 5 Amps and a little smaller than a mini marshmallow. It is located on the right side of the board as you face the back of the set. It will be in the vicinity of the connector comming up from the power cord adapter. To test this, check other voltages as described below first, as the power supply board must be removed to get at the bottom leads of the fuse.
If the light simply remains red no matter what button is pushed, the power supply board is the first place to check for faults. If you have a voltmeter, unplug the set and remove the center plastic panel of the set, this reveals a metal plate, which is retained by three more screws along the bottom. The base can remain in place.
With that plate removed, use care when it is plugged in as there is lethal v voltage potential on the right side of the opening as you are facing the back of the set. There will be two boards, the one on top with the metal plates visible is the power supply. The lower board processes the inputs into video and audio components and is the "A&D board", These are important to know if you are buying them off of Ebay or other internet vendor.
With the set unplugged look for a mounted connector on the left side near the top where 2 sets of multiple wires come out of it and plug into a pair of connectors on the lower side of the power supply board (Black,red and another color) There are multiple red and multiple black wires- in the mounted connector, there is just enough room to insert a probe tip with a little bit of force, just enough to ensure the tip is in contact with the conductive connector in 1 each of the black; insert the black test lead from the meter, and the red test lead of the meter to one of the red in the larger mounted connector. The several red wires attach to the same copper pad on the power supply board so only one measurement needs to be taken to determine if power is available for the inverter board or boards. The black wires attach to one pad as well. With the meter set to it's highest DC voltage scale, plug the set back in and switch to lower scales as needed to ***** a avoltage measurement. see if you have a voltage in the area of 24 volts. If you do- check the fuse(s) on the inverter board or capacitors of same boards (depends on production run.
If you have 24 volts, the blue pilot lamp should be lit on the front. You can see on the face of the set if the tubes are lit or not. If you have 24 volts but no light- the fault is with the inverter or the CCFL tubes. The inverter should be pretty obvious if it is the issue because the capacitors will have bulging tops. The chip fuse for each section should checked for continuity If there is, the fuse is good. These require a high ripple current type of electrolytic capacitor. A general purpose type will not last in this location.
If the set has the CCFL's lit, but no response to an input signal, move the test leads carefully, or unplug set to move them to the corresponding red and black wires of the bundle that plug just above the paired sets that go to the inverters, the upper set has 3 red, 3 black, and 2 other colors on the connector. You should see a voltage measuring between the red and the black. If no voltage, or less than about 3 volts, the power supply board is at issue. If the voltage is greater than that, the A&D board is likely at fault, this is the board that is below the power supply board..
Dec 11, 2011 |
Polaroid Televison & Video