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Loss of colour from top of tv purple at the top with a bit of normal picture at the tube going

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Good day. It would have been a different scenario if the problem is your tube. The one that your having is a mere problem with the loose contacts in your units circuitry. Also, the terminals of your deflection yoke must be reoldered..


Posted on Mar 29, 2008


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1 Answer

My tv has a purple destorted colour

It maybe due to the disorder in the picture tube of your T.V. or it maybe the moisture in present in or on the picture tube. Try to clear out the moisture and if it dosen't work then change the picture tube.

Sep 24, 2012 | Televison & Video



Sony Trinitron sets are of CRT [Caothde Ray Tube] types. The common fault seen in these type of TVs are any one colour predominant on screen wih sound OK. Either red, blue or green colour with some thin horizontal lines at about an inch apart will be seen on the entire screen. This is totally a display card problem, which can be seen pluged onto the picutre tube neck. There are three electron guns for every picture tube, which emits red, blue, and green beams, which in turn illuminates the phosphor on the screen to get that colour. If no emission from all guns, results in a blank screen, ie black screen without any disply at all. The three colour beams together produces proper coloured picture what we see on screen. These three gun's terminals are brought out by pins of the picture tube outside to which video signals are given in appropriate proportion to produce a TV picture. Normally, all these three pins are biased with a voltage of about 170 to160VDC+ve. Take one colour gun, as an example and and let me describe the problem.
Let it be a green gun. These guns are called cathodes of the picture tube. If it gets a voltage with respect to its grid, it will emit electrons according to the voltage applied to it. This is a negative process, that is, as the voltage at this pin drops, its emisson incresses and vice versa. If the emission increase, the colour with respect to that gun also will increase and gets predominant at the screen. So when we see a green predominant screen, there will be less voltage at the green cathode with resepect to the other two. If red colour is predominant, the voltage at red cathode will be less than the other two. If blue colour is predominat, the voltage at the blue cathode will be less than the other two.
We must find out the reason for this fault first. Assume that your Tv has a red predominant screen with some thin lines across it, at about one inch apart of the entire screen, it is clear that the the red cathode voltage is very lower than the other two. the main reason for this fault, normally seen in most of the Sony Trinitron, are loose soldering points either to the picture tube base socket or the resistor connected between the red drive transistor's collector point. Resoldering the most of these points on the base card by applying a little more solder will rectify this probelm. Other possibility is shorted video output transistor of that cathode. A direct short [collector to emitter] of these transistors will drop volatge to very low at that respective cathode of the picture tube, and that colour will be pridominant along with lines. Replacing the transistor will solve the problem. In some cases, the resistor connected to that transistor may have blown out. If so, it should alo be replaced. Whatever the case may be, voltage at the respective cathode that emits colour will be very low with respect to the other two. Find out the reason and rectify it. You can compare the voltages of the other two cathodes with respect to the faulty colur cathode. Cathode pins will be marked on the base card, and can be identified. It is best to pull out the base card from the picture tube neck and place it somewhere a safe place without shorting it with other parts of the TV. You can measure the voltages of these points very easly, without fearing the damge to the picture tube. After all are found Ok, replug the base card and switch on the TV. The set will be alright. In rare cases, chroma IC also can be a reason for this fault. if it is faulty, after a short period after switch on the TV, the IC will overheat and shutdown the entire system.

on Mar 21, 2011 | Televison & Video

1 Answer

My tv has a huge circle on the centre and its showing weird colours purple and blueish colours to be exact.

Check its picture tube connecting socket. You can locate it on the pictur tube base card. Replace it. Focus voltage connection to this socket is defective.

Apr 06, 2012 | Televison & Video

1 Answer

Bush tv picture colour red&purple

Check for any loose soldering points on the video output card [ a circuit baord located at the neck of the pircture tube]. Resolder all the suspected solder points. Green colour out put is absend now with your Tv.

Mar 14, 2012 | Bush Televison & Video

1 Answer

When I turn on my Gundig TV the sound is there, but the picture does not come for about 15 minutes. It starts off blue then slowly changes colour and eventually comes on. The TV is only 16 months old....

It may be due to the fault of its picutre tube base socket. Some of them may show this type of fault eventhough it is a new one. Picture tube base socket is located at the picture tube bas card itself. It is directly soldered to the base card, throu which the connections are going into the picture tube via its pins. You just open the tv, and pull it out [not make any shakes while pulling it, as that may bed the picture tube pins, or iven break the picture tube neck. Just pull it straight out, and refit it at the same way as you pulled it out, for two or three times. Sometimes this will retify the fault, as this process will remove any loose contact between bascard socket and picture tube pins.
If this doesn't hlep, desolder it out from the picture tube base card, go for a similar type and pin confuguation. Replacing it will solve the problem. As you replacing the base socket, look into the base card for any loose soderings are there too. OK.

Nov 08, 2010 | Grundig 21" TV

2 Answers

Picture turned completely purple

As far as picture and sound is there, your TV has problem at its video output stage. Purple coloured means there is no green emission occur in the picture tube. in otherwords green colour is absent in your TV. This type of fault is related to its video output stage only. Can it be a loose contact or transistor or Ic failure. As your tv is 36" screen size one, you must be cacious to take any repair by yoursef, because its final anode voltage comes around 27KVDC [27,000 VDC], and is dagerous to hold. Anyway I will guide you what to do.
First of all, you just give a small hit with your palm on the top of the cabinet of your TV or its side. Do not use any hard material, only use your hand, and see the colour becomes normal atleast for a second or not. If it comes normal this way, you can make sure that there is some loose soldering occured inside your TV. If it does not help at all, be sure there is some electronic component failure has occured.
If it is so you have to open your TVs back cover, not spoinling anything and cauciously. Keep the power cord of the tv from the wall socket before opening the TV. As you open the TV you first notice a circuit board attached to the base of the picture tube. It is called the base card. It is pluged into it with the help of a socket, and it can be detached from it by slight pull back. You shoud do this very causiouly because picture tube neck, where it is fitted is more thinner than other part of it and it is very nice.
Before pluging out it from the picture tube, keenly notify on its soldered joints for any kind of loose soldering hav or not. There are three cathodes emitting light of three different colours inside the neck of the picture tube. They are Red_Green_and Blue. In your Tv green catode is not emitting any light. Take the voltages of the other two cathodes Red and Blue. Compare this voltage to the voltage now at Green cathode. It will be higher than other two now in your TVs case. Normally all the three cathode voltages should be almost equal to each other, provided a small difference, say 3 to4 VDC is allowable. If the voltage at the Green cathode is found high, it is clear that the transistor or Ic connected as video output of that cathode is out, that is damaged. You should repace the same to make your TVs colour normal.
These are hot services, that is you can oly take voltages of the above mentioned points with your TV pluged into mains votage. All precautions should be taken before attempting anything. Keep children away from you, and let an adult be nearby. Do only if you have confidence and a liitle knowledge about the circutary. Otherwise get the service of an experienced service personal. Ok.
If you feel any difficulty or doubts, inform Fixya about it; they will give me alert.

Oct 21, 2010 | Proscan PS36125 36" TV

1 Answer

The color sometimes bleeds and takes over the whole picture. I have to change channels to ge it back to normal - it happens on any channel - none in particular - it is only 4 years old

You are reporting about color "spreading" I thinks. That is colour spred like taills along with picture. Red colour will show it more. There are 2 main couses for this fault. The first one is picture tube aged. The second one is low video output drive voltage. As your TV is new [I can say as it is only four yerars old], the second stated may be the fault.
Check the video output supply voltage. This voltage point can be located at the base card [a square or rectangular printed circuit board pluged into the neck of the picture tube]. It should be above 250VDC. If it is there come to the Red_Blue_Green cathode of the picture tube, [they are all also in the base card itsef]. All this voltages are almost equal to each other, provided 2 or 3 volts difference is normal. If any of them is found too low than normal, check the related videou output transistor. Check the electrolytic capacitor [usually 10MFD or so, 450v] connected to the video output voltage supply rail, and normally can be located at the base card itself. Ok
Keep children away from you, when you open the TV. Be caucious, as 25KVDC [25,000VDC] points are there inside your tv. Keep an adult beside you as a precaution. Never touch any internal part of the tv while it is switched on. Plug it out from the mains socket before doing any componet replacement, except for voltage measurements. Do wear a plastic or rubber footware when you work, and never use a metal chair.

Oct 20, 2010 | Sony KD-32FS170 32" TV

1 Answer

Problem with a colour display on Hisense tv

If your picures are all purple it means that the green colour is missing. TV colour is made up by mixing Red, Green & Blue. Removing Green leaving Red & Blue makes purple. Study the green colour circuit for a fault and confirm that the green gun inside the tube is working.

Aug 31, 2009 | Hitachi 60SBX78B 60" Rear Projection...

1 Answer

Purple tint

Do not put a colour television near a strong magnetic field. I have confirmed from several experts that this has the undesired effect of causing loss of colour

Jan 10, 2006 | Panasonic CT-27SF26 27" TV

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