# Polaroid 4011-tlxb flat screen power problem



## chatterx (Feb 12, 2011)

I have a Polaroid 4011-tlxb 40" lcd tv here that seems to have a power problem. When I turn the television on, the upper left of the power board will make three high pitched squealing noises and then the red light on the bottom left of the power board will start blinking. The status light in the front will remain blue the whole time. When the tv starts its squeal the picture will come on and then right back off till the next squeal. If I move the burn dipswitch to the on position and turn the tv on, it will constantly squeal but the screen stays on. I am beginning to suspect the power board as this seems to be where the problem is taking place. Below is a pic of my board. I greatly welcome any feedback on this issue. Many thanx in advance.


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## octaneman (May 13, 2009)

Hi chatterx 


Does the squeal have a high pitch to it ? if it does its coming from the transformers to the inverter board. Take a meter and set it on ohms scale, test the primary and secondary windings on both transformers. One or both have gone bad, also test to what appears to be regulators that are on heat sinks, there is a good chance that they have burned out.


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## chatterx (Feb 12, 2011)

Sorry for the delay in replying. It is a high pitch squeal. Unfortunately my knowledge of how to test electronics is limited at the moment. I know how to check diodes, capacitors, and resistors. I did a quick google search to see how test the transformer but ended up with various methods. Does the transformers have to have power going to them to test them. Sorry if this sounds so noob, but I am learning as I go along here. If you have a link to some reliable, understandable information on how to test them then I am more than willing to study it and try it.... I am just a little leery about testing with power running to it if need be.... I guess it is a noob fear of getting shocked. It goes back to the days of when I was tinkering with tube tv's and got the bright idea to put my finger over the picture tube hole where the flyback cable goes LOL.

I see 4 legs on one side of the transformer and 3 on the other side.


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## octaneman (May 13, 2009)

Testing transformers is simple but first you have to determine if it is a step up transformer or a step down transformer. If it's a step up transformer take your DVOM and set it to AC scale, the voltage on the primary side will reflect what the input is. If readings are zero the transformer is gone. 

If its a step down transformer set your meter on AC and place your leads to the secondary side. If you get zero voltage on the secondary windings then the transformer is gone. 


Transformers have a center tap, so it very important when you are testing for voltages remember to cap off any extra wires or pins that you are not probing. Wrap the ends with tape or mirretts so they don't touch one another or anything metal because you risk burning out the transformer.



Here's an awesome site with tutorials on transformers and allot of other neat stuff on electronics. 

testing transformer


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## b_loc1 (May 3, 2011)

I have this exact same problem. Did you ever figure out what was wrong with the TV?


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