Question about Televison & Video
SYMPTOMS: Rising Black Horizontal Area and Right Side slight Pincushioning (bowing) of the picture. Clears up after the TV warms up for about 12 to 20 minutes. DETAILED DESCRIPTION: The sound and all other functions are working fine. The picture has a Black Horizontal Area (I will call it "BHA") that spans the full width of the screen. That BHA appears from the bottom of the picture and then rises up the screen, until it gets about 75% high, and fades when it gets to three quarters (75%) from the bottom. That is, the top 25% of the picture is completely unaffected and always looks fine. The BHA looks like a completely blacked out area, surrounded top and bottom with finer and finer horizontal black lines. So it looks like the fine black horizontal lines are concentrated in the middle, and spread out more on the top and bottom of the BHA. This BHA is about 25% of the screen's height at first, and gets smaller and smaller as the tv warms up. The BHA rises to one quarter from the top of the picture and completely fades, and then rises again from the bottom and again fades and repeats this as the set warms and the BHA gets lighter until it disappears. THE BHA seems definitely related to the slight (1inch) black pincushion bowing in of the screen on the RIGHT HAND side of the picture. That black bowed area runs from about 3 inches from the bottom of the right hand side, to about 5 inches from the top of the right hand side. The BHA, when the tv is almost warmed up completely, seems to stop at the top of the bowed in area, so I think these are both symptoms of a single/related issue. The picture is showing all the time, while the BHA is moving up across the screen. Any ideas about this?
Yes, this is rare but I have seen it before--not fixable if it is what I think it is----It is what is called a Dome effect---the shadow mask in the picture tube is actually contracting and or expanding depending on temperature---
Directly behind the phosphor coating (the stripes that you see on the screen) is a metal screen--the holes or perforations in it line up with the stripes on the phosphor screen.
Some masks either have a material or a defect causing the dome effect----Not likely to be anything else---a Pin amp problem will not usually act the way you describe but a shadow mask inside the picture tube will act exactly that way.
Posted on Dec 05, 2012
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Posted on Jan 02, 2017
Yes, definitely worth fixing. The problem lies in the vertical deflection voltage-doubler circuit. The usual fault is a single capacitor of 100uF/35V that has failed. It is normally connected to a rectifier diode right at the vertical IC. Replacing the capacitor (no more than USD4.00 in price) usually gets it working perfectly again. If you are finicky around technical work, then a reputable local repair shop in your locality should do it quickly for you and charge only labour.
Posted on Jan 18, 2008
My Toshiba required replacement of two of the vertical filters/capacitors. Doesn't take long and the parts are inexpensive, but requires a repairman.
Posted on Sep 12, 2008
sounds like bad capacitor in vertical circuit. It's not a hard fix if you know where to look. Repair shop should not have hard time repairing it.
Posted on Aug 10, 2009
you have to take in affect on how old is the tv if you have had it a few years then the screen is going out and will only be a matter of time before it goes all the way out and you will be buying a new one if it not old and its one of the newer flat panels then its the signal that the tv is receiving if its hooked to a digital antena then you only get max of 720 from it on certain channels no matter if the channel or channels are showing hd with out a hd source your tv will not show better then that i have a 42 inch hd flat panel and use a antena and the best i get from my hd broadcast channels certain times will i get true hd like when the news is showing or when one of the series that was filmed in hd is on other then that i only get a 720 picture instead of a 1080 most commercals are not film in 1080 but in 720 max and i dont know why makes no since
Posted on Aug 28, 2009
You have a poor solder connection in the frame output stage. If you have a soldering iron, remove the back cover & look for an IC that will be attached to a metal plate that acts as a heatsink. Carefully re-solder the pin connections on this IC ensuring you dont leave any of the pins shorted together. If you spot any other connections around about this area also looking dry, then resolder them as well.
Posted on Oct 19, 2009
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