Question about Toshiba CF20F40 TV

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No raster no sound no picture only brightness

Toshiba tv i have for 5 years, the problem was tv on full screen brightness ,no sound ,no picture. but could change tv channel,see look like very dull picture, i try replace back same # flyback & memory ic that two way didnot done problem. please heip me & give me a good idea to fix up this problem .thanks

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Re: no raster no sound no picture only brightness - Toshiba CF20F40 TV Standard (CRT) Televisions

Just buy a new tv,

Posted on Dec 10, 2009

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Re: no raster no sound no picture only brightness - Toshiba CF20F40 TV Standard (CRT) Televisions

My tv wont turn on

Posted on May 27, 2008

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No picture, no menu, black screen, no raster, sound ok

From your detailed description, it sounds that the main chroma processor IC has damaged. Raster means nothing, but the lighted screen that appears, when a TV is switched ON. For some brands, there will be a blue screen; when there is no signal input, and some others will have a bright white screen with some snow.
I advice you to contact any service technician, to get this TV repaired. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" or "Magazine" will make surf easy. Pull up older posts. Surf the site with patience. Do a search by type in the brand name of your device at its search box and press "Enter".

Jul 07, 2014 | Standard (CRT) Televisions

1 Answer

No picture but has sound

First make sure that the brightness and contrast are turned up.If the screen is lit up (that is you have a raster) then the problem would be in the video circuits.If the screen is not lit then you have a problem in the deflection circuits.A good possibility,with no raster,would be the Horizontal output amplifier.If you are not familiar with circuitry you would need a tv do the repair.

Sep 14, 2013 | Toshiba 32AF43 32" TV

1 Answer

Toshiba CZ32V61 no picture

1) you have problem with the Raster
2) the main causes are a) raster b) picture c) sound d) synch
3) since this are not video, the problem is raster. your must
test the voltage from section horizontal out +125vdc+vertical output +80v+all other circuit +12vdc
4) test the power supply for defective. see the diagram attached


Jul 12, 2012 | Toshiba CZ32V61 32" TV

1 Answer


How long u have this RCA analoge tv?Around 10 years or more and used it like about 5 or 6 hrs everydays?Yes,than ur tv it is losing CRT tube radiation cohetion.As times go bye years in years out the tv CRT-(tv tube) radiation will slowly dying out,Tv actual pictures will lost some of it luster and it brightnesses to the tv auctual pictures.Brightnesses of CRT tube will get darker and darker until the tv actual pictures barely it is watchable anymore.Contrast,Brightness and Colors adjusting more will help some.But u have to take this tv aparts and take a Flat scerw driver turn up a little bit more of the tv HV-(high voltage) SCREEN button on the FBT-(flyback transformer) to make any big differences of the CRT tube brightnesses.The FBT-(flyback tranformer) is the big block of plastic with a red wire with a black cap hook up to the tv CRT-(tv tube).This adjustment on of the FBT,HV-SCREEN button will help the tv CRT-(tv tube) last another year or two.

Aug 16, 2011 | RCA TruFlat 27F520T 27" TV

1 Answer

Picture to wide

This trouble symptom picture wide or"blooming", the picture becomes dim even with the brightness control full on,and there is an abnormal enlargement of picture or raster.Usually,the enlargement is uniform,but there may be some defocusing.In some circuits,the brightness control operatesin reverse(rotating the control for an increase in brightness produces a decrease) after reaching a critical point on the control. If the picture wide is not accompanied by insufficient width(a symptom of horizontal output failure) the probable cause is a high volatge circuit ony,particularly the HV rectifier and HV winding.Any circuit problem that reduces but does not completely eliminate the high-voltage output to the picture tube second anode can cause overscan. The most likely defects are leaking high-voltage capacitors,defective high voltge tube rectifiers,leaking high voltage leads,defects in high voltage circuit protective resistance,and shorted turns in high voltage winding of the flyback transformer.

Hope this may help you;



Sep 06, 2008 | Toshiba 32AF45 32" TV

1 Answer

Sanyo TV Model# DS32224

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.

Jerry G.

Nov 09, 2007 | Sanyo DS32224 TV

1 Answer


do you see anything on picture doesnt mean no raster ,raster mean anything that comes out in raster with sound only mean failure in either,connection in heater which means, loose connection or some new sets declare failure in vertical be more specific ok?

May 08, 2007 | Sony FD Trinitron WEGA XBRKV-40XBR800 40"...

1 Answer

Tv showing blue screen with flyback lines sound ok

Flyback lines? Is the picture all white with no brightness control with faint horizontal faint lines? If this is what you are saying, the screen voltage could be bad, and if thats the case, the picture tube or the flyback itself could be bad. You could also have a bad connection on the crt socket

Dec 27, 2006 | Philips Magnavox 20MT133S 20" TV

1 Answer

Toshiba 27A51 problems

reduce raster no picture no sound and the power stays on.

Oct 27, 2006 | Toshiba 27A51 27" TV

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