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Hi Please try testing each voltage of RGB output in the small pcb attached to the CRT. If one of these voltages is missing (they are tipically almost of the same value), replace its output transistor. If all voltages are present, but very high (above 180V), please check the filter capacitor in the RGB supply voltage line near the flyback transformer (47uF/150/200V) by replacing it. It is cheap. Please be careful when dealing with high voltage section of a tv set as capacitors may store a letal voltage. So disconnect the set from main and discharge any capacitor before dessoldering it.
First, try a hard reset.
You must unplug the power cord (turning off the set or the strip will not do it) for a couple of hours, then try again.
This will sometimes correct the problem
When it blinks off: Does the raster go dark or just the picture and the raster remain? If the raster goes dark when it blinks off it means there is a loss of high voltage to the picture tube. High voltage repair is expensive. It may be a failing flyback transformer that is functional inside the horizontal deflection circuits. If the raster stays on and you just lose video (picture information) then it may be a simple intermittent IC chip in the video board area. It may require a technician to determine which IC and how to replace it or the parts associated with it, but probably not terribly expensive to repair.
Is that diagonal thin line about 10 to 20 degree slant? And then you have a very bright raster?
Then you set the flyback(for tube tv), I think its "screen" voltage is set too high adjust it slowly to lessen the brightness. It is commonly a small pot on the side of the flyback together with the focus pot.
If you have raster turn the tv on, use insulated screw diver, then slowly turn the knob to the direction(CC or CCW) where your raster go dim.
Be careful your dealing with live and high voltage. If your not inclined on electronics better not to.
check the high voltage with the screen control turned up high where there is no raster. suspect problem within the video circuit where there is no high voltage or defective picture tube.some time when the screen is black and the screen control advanced,you can see if the tv has video or vertical or horizontal problems on the screen.service the high voltage circuit if there is no raster or high voltage is seen.no raster can be caused by the no heater or filament in the CRT.----
a defective picture tube can cause many problems, such as, poor brightness ,missing colors,intermittent picture,poor focus,a single-colored raster,arching in the gun assembly,retrace lines in the picture,negative picture,chassis shutdown,noheater or filament lit and no raster to name a few.an open filament or heater can cause no picture or no raster symptom.a defective CRT can have an extremely bright screen.loose particles of the cathode element can lodge between the grids and cause an intermittent black and white picture. simply tap the ends of the CRT gun assembly and notice if the picture begins to flash off and on.----
with a leaky picture tube after turn on the raster dims and get extremely bright.a dim picture with no green in the raster can result from a bad green assembly. a heater-to-cathode short can cause a raster to change colour or a result in no raster at all.replace the picture tube if there is severe arching in the neck of CRT.
excessive brightness with retrace lines and a vertical collapse to a thin line can be caused by a bad coil on the neck board of the picture tube.rejuvenate the picture tube when there is very bright green screen.
check for the resistance change on the resistors of the CRT neck board for an excessively bright picture with retrace lines.excessive dust inside the CRT spark gaps within the picture tube socket can cause the very bright raster and the chassis shutdown.a defective video amp,luminance buffer,or reference transistor can cause a bright picture with retrace lines.
for getting any required parts to replace you can get it from
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It is not a good idea for electronic products to be in storage for long
periods of time. It is even a more poor idea to purchase used from a
rental center; the result is more often than not a very bad experience.
With no picture, but working sound, it is a loss of the high voltage
system. This is almost always failure of the high voltage
autotransformer called the flyback and/or the HOT (horizontal output
transistor) - which work together in producing the horizontal scan of
the raster system and the high voltage to prduce the raster upon which
the video picture is modulated.
The failure could very well be from HIGH temperature involved with the storage of the tv set.
The repair costs will be over $150 but not more than $300; depending on the exact parts that need replaced.
But: try the hard reset and the vibration/whacking test first to see if the moving business caused failures.
Hard Reset: Unplug for 4 hours, then try again. Do it twice.
The problem you are describing is definitely a bad picture tube.please replace it or the problem you are describing sounds like high voltage regulation problems. The easiest way to tell is by changing from a black raster to a white raster. If the size changes quite noticeably or jumps alot then you have a regulation problem. The first thing to do is check your high voltage while changing the raster from black to white. If the HV varies by a large margin, then you have a flyback problem. If it doesn't, check the voltage at the collector of the HOT while varying the raster again. If the voltage changes alot then check your B+ line. Typically what goes out in this case is a capacitor(typically 100uf-350v or so) or the B+ regulator. Hope this helps.
This is usualy because there is either a high voltage regulation fault, or a main power supply regulation fault.
There are many things that can cause this. When the high voltage goes too far down, the raster will enlarge. High voltage regulation can be caused by faulty components in the feedback sensing, or in the high voltage multiplier, or in the flyback windings itself.
A quick way to sort of know if the high voltage is regulating is to wind the brightness and contrast from one extreme to another and observe the raster size. If the raster is changing size with the brightness on the screen, the regulation is not working well. In some of the low cost sets there will be about a 2 to 5% raster size shift in this case. The high end sets will have a near 0% shift in the raster size. A size change of about 2% is acceptable for most sets. If the CRT is weak, this test will not work well, because a weak CRT will not properly load.
If the main power supply is operating slightly over voltage, the raster size will increase. Usualy, the brightness will be a little on the high side when the supply is too high. Voltage regulation faults can be from warn components in the voltage regulator area, or in the feedback control.
This should be looked after by an experienced TV service tech. This type of fault can be involved.
I don't think it's your picture tube, but it may be a problem in your high voltage power supply. If there is no anode voltage then there is no raster (light from the screen) or picture. If it is your high voltage section the you may want to think about taking the set to a shop because of the danger of electrical shock.
The high voltage should be around 29.5 KV and not fuctuate between 20-30 KV that would indicate a high voltage regulation issue then. Are the filaments lighted up in the neck of the CRT? If so then yes you are probably looking at a low voltage issue such as a 12 volt source or a a/v switching IC issue.