Question about Televison & Video
My Polaroid TV is having power supply problem. After 10 minutes of so, backlight turns off. I am electrical engineer, so I looked at circuit board.. Component NTC1 (Thermistor) Is getting to 90C after short time.. After blacklight cut off, part cools significantly.. Was wondering if this is abnormal operation for this In Rush Protection NTC Thermistor, and if so how can I find specs, as this is unmarked part..
Power Supply Circuit Board is: Proview IPOS 250 A40
TV is Polaroid TLX-04240B
When blacklight goes out, rest of TV (sound, and LCD rendering is working normal) Checked LCD with SPOTLIGHT.....
I have read everything I can find on the net about this problem for Polaroid TLX 04240b TVs (most, like mine, bought from Wal-Mart on Black Friday after Thanksgiving). I thought I was on a hot lead when I changed a 220uF 450v capacitor, but I still had the same problem. I saw a short post from somewhere else on this Fixya web site (sometimes I can find it again and sometimes I have trouble locating it) that said someone flipped a tiny switch on their circuit board and the problem was gone. I did the same thing and my set has been working fine. They had said their set was on for over 8 hours two days in a row when they posted. The other night my daughter left our set on over night for 20 hours and the picture still was working great. If you look through the top of the set when the picture is on you can see some white light at several locations, when the screen goes blank the white lights go out and a red LED light can be seen. If you take off the plastic cover on the back (3 screws) and then take off the metal cover (3 screws) this red LED light is on the upper circuit board in the lower left corner. Just a little to the right of the LED light is a small switch block that has 4 tiny white switches. I turned my set off and took the bottom switch (#4 and had the letters BURN by it) to the right "ON" position, turned the set back on and, so far so good. PLEASE NOTE!!! I know almost nothing about how transistor circuits work. I have no idea what the switches do or what long term effect this might have on the set. The set was only good as a paper weight before so even if this only fixes the set for a short time it was at least worth a try for me. Does anyone know what those switches are supposed to be for????
Posted on Aug 13, 2009
Testimonial: "Great information, thanks! "
Also could be just a few bad capacitors on the power supply, if you want you can do a visual of the power board caps will appear swollen on top and are easy to solder in cost about $1 each
look at the individual flouresent bulbs if one is dark or unlit before they all go off the panel is bad
Posted on Aug 01, 2009
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Posted on Jan 02, 2017
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