Rear projection TV (LG 44SZ51): Horizontal dark band on upper screen field
I have this TV for 3 years. 3 months ago, a horizontal dark band (not black, i can see the picture there but it is considerably darker than the rest of the screen) of about 10-15cm width (not perfectly straight border line) appeared. Initialy i thought it was humidity on the mirror. I opened the case but there was nothing on the rear mirror. I didn't want to mess around with other parts of the device and the dark band is still there... Is it possible that the lamp comes to the end of it's life and needs replacement? No indicator of such problem on the TV though. What could cause this? I don't know if i can find a technician for such a TV in my town... Any ideas are welcome. Thank you in advance
Re: Rear projection TV (LG 44SZ51): Horizontal dark band...
The LG 44SZ21RB Have a problem with their light tunnel collasping due to the heat from the lamp. They are available as a spare part @ LG and would also require some silicon adhesive to bond it into the assembly. Very tedious job for any technican (2-3 hrs). Lg will not release parts to the general public only to an authorised LG agent.
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this problem seems to have corrected itself although the dark patch at the top of the set is still present.
I cannot think of anything in particular that i may have done to fix it but i have resorted to turning the TV off using the on/off switch after using the remote. Other than that i removed/replaced the bulb.
so far, it is 3 weeks and counting since i last had any problems.
Hi, Its because of Over Voltage of Screen (G2) to Blue CRT. Take off front lower cover (speaker grill) and unscrew board. There you will need to find Focus Block mounted having 6 control knobs. 3 knobs are for Focus control and 3 are for Screen volts control. Find Blue Screen control knob and turn is Counter Click Wise slightly until bluish shade disappear on screen including few blue horizontal lines. If you select AV input to adjust that will be fine as you do not need to wait for dark-scene.
You will need to pull out the engine and check for any smudge on the lens. then proceed with the polarizers 3 of them they are sitting in front of the DLP chips, this is a delicates operation. the blue polarizer is the one which usually suffers burn-in (dark spots on the glass). if everything looks ok, then it means that the dlp chips are faulty, at that stage it will be uneconomical to be fixed.
Set starts, horizontal and vertical deflection work, HT ok, crt heaters ok, but no sound or picture
I turned the G2 voltage up and noticed a white screen with flyback
lines, frame ok. I detected two badly soldered double diode rectifiers
in the secondary part of the power supply ! I checked all other joints,
and everything was ok !! success
White horizontal line (no vertical deflection)
Check / replace R548, R549
Sound but no picture except for a couple of horizontal colour lines
Replaced the frame chip TDA8356, set now ok
If this model has a "lint screen" or air filter, I would check to make sure the set is getting proper ventilation. Otherwise, you probably have a bad solder connection or capicators going bad, causing your symptoms. Hopefully you won't have to get a replacement Printed circuit board as they are quite expensive.