- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
you did not mentioned if you have raster or none, if your tv has raster but no picture your problem is in your I.F. section and your tuner, now if no raster, you can check your power supply, check your 5volts, 9volts, and 12volts check any alternatives that cause of no picture..
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
www.radioshack.com
or from
www.partstore.com
or from
www.shopjimmy.com
---------
thanks.please do rate the solution.thank you for using fixya.keep updated.
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.
do you see anything on screen.no picture doesnt mean no raster ,raster mean anything that comes out in display.no raster with sound only mean failure in either,connection in heater which means, loose connection or some new sets declare failure in vertical circuit.so be more specific ok?
What you have described there is a classic example of the jungle IC failure. Ic301 Sony p/n 8-752-101-04. A pic with no color, and lines or grainy texture in the picture. Not a project you want to tackle if you don't have the proper soldering equipment or skills. And not a costly one at a good repair shop.. Only real hurdle is getting that heavy monster into the shop.
To answer your question, yes what you described there is raster. Even the salt & pepper looking screen with no real decernable image is described as raster. In fact any image generated on the CRT is raster.
And yes, these sets are prone to solder joint problems, usually ring cracking in circuits that generate the most heat.
Once you're ruled out your PC and video card by trying a different monitor, I would suspect the problem is a bad video / signal board inside the monitor.
If so, it needs component-level electronic troubleshooting to locate the bad part(s).
×