Over the last few weeks my TV has come on with either no problem at all or a thin bright line across the middle. (Left to right) If we hit the set from the sides it would correct most of the time. I know it is a vertical deflection problem from other web sites but what component should i be looking at for re-soulder or replacment. I pulled the circuit board and poked around and found nothing obvious or repeatable. Read that it may be a cold solder or bad cap but any clues where to start looking? Flexed the circuit board a little as well and nothing repeatable.
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Re: Vertical Deflection problem
I also suspect its just bad solder connections, the vert. o/p ic is maked ic451 look for all the ic's on heatsinks. it should have 10 to 15 pin all in a straight line & be attached to a small heatsink. if i remember right i think if you are looking at the tv from the back it is on the left side near the front (by the buttons/swtitches). resolder all the pins on the ic & resolder the parts just around the ic as they too also develop bad solder connections. just remember to check for shorted pins after soldering. good luck.
It seems to me that your set have dry joints, resolder arround the vertical section especially the vertical IC. Also check the horizontal section for dry joints.
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CAUTION: To prevent damage to the CRT phosphors, immediately turn down the brightness so the line is just barely visible. If the user controls do not have enough range, you will have to locate and adjust the master brightness or screen/G2 pots.
A single horizontal line means that you have lost vertical deflection. High voltage is most likely fine since there is something on the screen.
This could be due to:
Dirty service switch contacts. There is often a small switch located inside on the main board or perhaps accessible from the back. This is used during setup to set the color background levels. (On some sets, this is located on the CRT neck board and may be a jumper plug or other means of selecting service mode - not an actual switch.)
When moved to the 'service' position, it kills vertical deflection and video to the CRT. If the switch somehow changed position or got dirty or corroded contacts, you will have this symptom. Flip the switch back and forth a couple of times. If there is some change, then replace, clean, resolder, or even bypass it as appropriate.
Bad connection to deflection yoke or other parts in vertical output circuit. Bad connections are common in TVs and monitors. Check around the pins of large components like transformers, power transistors and resistors, or connectors for hairline cracks in the solder. Reseat internal connectors. Check particularly around the connector to the deflection yoke on the CRT.
Bad vertical deflection IC or transistor. You will probably need the service manual for this and the following. However, if the vertical deflection is done with an IC, the ECG Semiconductor Master Substitution guide may have its pinout which may be enough to test it with a scope.
Other bad parts in vertical deflection circuit though there are not that many parts that would kill the deflection entirely.
Loss of power to vertical deflection circuits. Check for blown fusable resistors/fuses and bad connections.
Loss of vertical oscillator or vertical drive signals.
The most likely possibilities are in the deflection output stage or bad connections to the yoke. Hope it works well...
If it is a bright line and there is nothing above or below the line, the TV has failed with a lack of vertical drive. This could be a transistor, a chip or the deflection coil. If the TV is more than a few years old, it will be cheaperr to replace it than to repair it.
It sounds like a vertical deflection problem. You mentioned you had a white HORIZONTAL LINE in the middle of the screen. If this line runs from left to right across the screen it's in Verticla deflection. If it runs from top to bottom, it's in Horizontal deflection. I am assuming the problem is a Vertical deflaecion problem. The repairs necessary are most likley to replace the vertical capacitors or the verticla deflection chip.
NC Electronic Mills, Wyo USA
yes it can still be fixed! the pop sound you've heard maybe came from a blown capacitor in the vertical deflection circuits. this symptom, sometimes called the tube light effect, it is characterised by a bright thin horizontal line across the middle of the screen. this symptom is caused by a breakdown in the vertical deflection circuit. hence maybe the trouble maybe in the vertical oscillator, amplifier or output circuits. but if all i have said is not clear to you, better bring it to a qualified tv technician. good luck!
this symptom, sometimes called the tube light effect, it is characterised by a bright thin horizontal line across the middle of the screen. this symptom is caused by a breakdown in the vertical deflection circuit. hence maybe the trouble maybe in the vertical oscillator, amplifier or output circuits. but if all i have said is not clear to you, better bring it to a qualified tv technician. good luck!