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Palsonic 5139 green down sides

 
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dahbrown



Joined: 31 May 2007
Posts: 31

PostPosted: Mon Jan 21, 2008 11:10 am    Post subject: Palsonic 5139 green down sides Reply with quote

Hi. I have a Palsonic 5139 Tv (Australia from K-Mart). There is a problem where the colours down each side are green. The middle section of the screen is OK.
I don't have a service manual or a circuit diagram. I am not sure if Palsonic are still in business and if these are available?

What could this be casued by?

Thanks
Dave
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torbjorn



Joined: 07 Jun 2007
Posts: 370
Location: Sweden

PostPosted: Mon Jan 21, 2008 4:22 pm    Post subject: Reply with quote

If it is a conventional CRT tv and the discoloration is there also when viewing a monochrome picture (turn down the color saturation or view a noise picture), then it is a color purity problem.

It might have been caused by a strong magnetic field near the tv, that has caused so strong permanent magnetization of the CRT's shadow mask that the internal degaussing coils cannot remove it. A common cause for such a strong field is starting a electric motor (i.e. a vacuum cleaner) near the tv.
Another common cause is kids having played with magnets at the screen.
In this case, the CRT has to be degaussed with an external degaussing coil.

Another possibility is that the internal degaussing circuitry does not work, for instance the PTC resistor can be faulty or there can be dry solder joints. When the degaussing does not work, it is normal that permanent magnetism builds up in the shadow mask from time to time.

A third possibility is that the purity adjustment has changed, for example if the deflection coils or ring magnets at the CRT neck were not properly secured.
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dahbrown



Joined: 31 May 2007
Posts: 31

PostPosted: Wed Jan 23, 2008 10:49 am    Post subject: Reply with quote

Thanks for the advice. I don't think that a magnetic filed would be the problme in the cabinet that it is in. There is nothing around it. Kids are too small to blame too!!
Not sure where to begin without a schematic.
Where would I check for dry joints around degaussing circuitry or PTC resistors?

Many thanks
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torbjorn



Joined: 07 Jun 2007
Posts: 370
Location: Sweden

PostPosted: Wed Jan 23, 2008 12:39 pm    Post subject: Reply with quote

Usually the degaussing circuitry can be found near the AC power input of the tv. Either at the mains switch or at the mains rectifier bridge. It is easy to follow the cables from the degaussing coils.
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Guest






PostPosted: Tue Jan 29, 2008 10:19 am    Post subject: Reply with quote

Looks like the posistor is faulty. It is only measuring less than 1K across any terminals.
I will replace this and see if I can borrow a wand to degauss the set.
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dahbrown



Joined: 31 May 2007
Posts: 31

PostPosted: Tue Jan 29, 2008 10:21 am    Post subject: Reply with quote

Looks like the posistor is faulty. It is only measuring less than 1K across any terminals.
I will replace this and see if I can borrow a wand to degauss the set.
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dahbrown



Joined: 31 May 2007
Posts: 31

PostPosted: Thu Jan 31, 2008 10:08 am    Post subject: Reply with quote

Yes, PTC is faulty. Degaussed the TV with the wand and replaced posistor and all good now!

Thanks for your asistance
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