Tuesday, June 25, 2013

HOW TO TROUBLESHOOT PLASMA TVs - Part of the screen do not work - Vertical & Horizontal lines - Refuse to switch ON etc:



HOW TO TROUBLESHOOT - WORKING PRINCIPLE 
The idea of plasma display is to illuminate a colored substance to form an image.  You see on the screen is burning gas between to pieces of glass. The gas is neon or xenon.  The estimated life span of a plasma display is 45,000 to 60,000 hours.  The serene contains a complex structure, has millions of colored pixels.  Each of these pixels are powered by tiny electrodes, has ists own gas and color. Each one controlled by brightness and color.  It is plasma display.  Usually plasma display problems start with its screen.  If a plasma screen is broken or crashed, it is not repairable by no way.  It needs a new screen replacement, which might cost around 2/3rd of the total cost of a new plasma TV.  The front protection screen glass can be replaced and is not so expensive.  If you have just a protection screen damage problem, after the replacement of the same, TV will work without any problem.  Plasma screen have aluminum base, and two pieces of glass with gas in between them.  The gas is not rechargeable.  Pixels with gas, controlled by tiny electrodes. Each pixel contains three colored sub pixels of Red, Green & Blue.  The plasma screen works in two steps. [1] Gas ignition [2] Picture reproduce.

Ignition => power supply => logic control => Z or X sustain => screen.
Picture => power supply => video control board [otherwise called as scaler] => logic control board => Y-sustain => X-sustain => buffer boards => screen.
Defects to screen.
Flashing red dots or pixels on the screen when it is cold.  even though after some time it might disappear.
Color distortion at one part of the screen, either be its left or right corner.
Colored vertical line/s on picture
Flashing red dots on some part of the screen, or all around.
BURN IN IMAGE
This is an image you notice on top of the normal picture.  It is usually displayed as dark lines or dark area on the screen.  The static [still] image display for along time will develop burn-in spots.  This is not a repairable issue.
VERTICAL/HORIZONTAL LINES/BAR
The problem might be due to a dead driver [part of the screen], or poor connection between plasma glass and ribbon wire connector. PDP panel and address driver on it are not separated.  If one of drivers is going out, need a new screen replacement. Defective buffer boards cause other common problem with lines on screen.  Voltage needed to operate controllers on buffer is high for a small SMD IC.  They are mot strong enough to drive address electrodes.
Plasma TV is a very hard working device.  It is working harder than any other TV, which has been built before, and produces a lot of heat. Overheating causes 80% of technical problems to it.  If there is no active cooling system, most of the plasma TVs will die in the first 3 to 6 years. After about 5 hours of work without cooling system some of the components on power supply regulator board were out of temperature balance.  Vs voltage changes up to 2 or more volts.  This may lead to overheating problem and cause other permanent damages.
POWER SUPPLY
In a plasma TV, it develops voltage to supply all the components, high current-high voltage.  Input fuse is of 10 Amps, with not so many TVs in TV history use input fuse of 10Amps.  Very sensitive for input AC voltage and output DC voltage.  It is a good idea to check the electric outlet, before hook up the plasma TV. All connections should be perfect in all respect.  A sparking electric plug connection can damage the TV.  Never use chap extension cords, and very old electrical connections.  Keep in mind that the plasma needs twice as much input current.  Common power supply problems are:
Hard to turn ON.
Stops working after a while.
Does not turn ON at all.
Flashing pixels on screen.
LOGIC CONTROL, X,Y USTAIN & BUFFER BOARDS
Controls picture, fires the gas, and many other functions.  Common problems include negative image, no image, vertical or horizontal stripes on picture, turns ON and OFF, and many more.
CARE
Cooling system.
Good electrical plug & connections without any loose contacts.
Do not leave the TV on one channel for a long time, say  2 to 6 days.
Do not use plasma TV on the same electric line with other powerful units, such as electric motors, electric cutters, welding equipments etc:
Standard companies build their own product, there own components, and have there own design.  So when you determine to buy a plama TV, care the Brand you’re looking for.  Never choose it from exotic companies, as they do copy and paste.

PLASMA TV FAILURE SYMPTOMS
No power supply  => Power supply.
Hard to turn ON. No power light on front panel. => Stand-by power supply.
Power turn On after 20 minutes of so.  Turn ON and shuts dow immediately. => Stand-by voltage. 
Flashing pixels on screen.  Turn ON, but no video and sound. => Board.

Negative image.  TV turns ON and shuts down in 2 seconds, or Z flashing pixels on screen.  Dark image => X or Y sustain board.

Has sound, but no picture.  Screen goes blank and then return to normal picture.  Vertical color lines on the screen, no video. Vertical color lines along with video.  Vertical bars on screen.  Horizontal lines on image.  Picture turns ‘Red’ after a while  => Sustain boards should be checked.

Left part of the screen only works.  Right part of the screen only work. = > Logic board
Vertical & Horizontal lines on screen.  Part of the screen do not work.  Some functions do not works. No video, but has sound. => Control board.

Part of the screen not working.  Black vertical bars on screen.  Burning smell. Vertical color line size changes.  White or colored horizontal lines => Buffer Boards.

No video from one of the inputs.  No sound.  No video, but have Menu lettering on screen. Some channels not working properly.  Snow on screen, no video at all. A gray colored screen try to shut OFF. Picture gets distorted after a while.  Intermittent sound.  Want to bring Menu on screen but shuts down for no reason.  Dark image on part of the screen.  =>  Audio/video main board.

Burn-in image.  Static image from previous seen channel or show.  Clears in few minutes.  Turn ON and shuts down.  Flashing red dots when it is cold.  intermittent change of colors => Plasma Panel.