Question about Toshiba 27DF46 27" TV
I recently purchased a floor model (Toshiba 27DF46) at an electronics retailer. it worked fine for about 3 weeks, then started randomly losing picture to a single pixel-wide horizontal strip across the screen for a second or two then return back to normal. over the next month it was happening more and more, and now, no picture shows up, just the line of light...almost seems like the whole picture has been squashed into that one line. again the sound still functions normally. Any thoughts? thanks!
This is actuall quite a simple problem... What you have explained here is a loss of vertical deflection. By the symptoms you described, working now and not working it's most likely the the vertical IC an LA7847-E has probably become ring-cracked at the point where the pins are soldered to the pc board. Depending on how long it has been allowed to arc the IC may have failed also, but they are not terribly expensive or difficult to repair - at least not here in the shop. The main board has to be removed. Locate the vertical IC - it will be mounted to a metal heat sink and the IC will be stamped LA7847. Then turn the board over and inspect where the pins are soldered to the foil side of the board. One or more will look ring cracked or fractured all the way around the pin. At this point you have two options, carefully reflow solder over each pin and put it back together or replace the IC by de-soldering it and removing it from it's heatsink. remember to use a good heat sink grease when applying the new IC.. There should also be a couple of caps in pretty close proximity to that IC... One should be about 50v/100uf and in the shop here we test em all... You might also just replace that one for good measure - they're not expensive either... If any of this sounds too complicated take it to a reputable shop and pick it up in a day or two.. Job shouldn't be that expensive or time consuming. My record in the shop here for doing those is 15 in one day. Average cost for that set, we charge is under $100 if you bring it in and pick it up.. Hope this helps Bill If you're calling around to the repair shops you might just ask if they have that IC on-hand or if they will need to order it..
Posted on Jun 07, 2007
I had the same problem and resoldered the connections to the vertical amplifier, but it did not fix the problem. Then I looked at the thermal connection of the amplifier to the heat sink and noticed that the thermal grease only covered part of the area between the amp and the heat sink. I unscrewed the amp from the heat sink, removed the thermal grease, and then screwed the amplifier back on to the heat sink (with no grease). Now everything works fine. I will add thermal grease when I get a chance. I think that the problem was caused by a mis-application of the grease at the factory. It looks like the grease was there, but not in the right position to be effective.
Posted on Apr 10, 2009
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