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Red horizontal lines on sony KV X2993B
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micmoc
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PostPosted: Sun Dec 04, 2005 11:48 pm    Post subject: Red horizontal lines on sony KV X2993B Reply with quote

Hello,
I can see the horizontal return of the beam as red lines on my sony tv (AE-2F chassis) :



This happens randomly for some minutes and then reverts back to normal appearence.

Any idea ?
Thx in advance.
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PostPosted: Mon Dec 05, 2005 12:10 am    Post subject: Reply with quote

Did You check the Power Supply? (for example quality of voltage)
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PostPosted: Mon Dec 05, 2005 5:44 am    Post subject: Reply with quote

first check dry solder on r\g\b drivers board that mounted on the crt neck. seconde you can measure the 1000 & 200 +dc lines on the same board.
if ok it seems to be an instant leakage between the grid & the cathode of the red gun
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guest2
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PostPosted: Mon Dec 05, 2005 6:22 am    Post subject: Reply with quote

Too high screen voltage, or weak CRT. Set the Screen voltage on the CRT board.
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micmoc
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PostPosted: Tue Dec 06, 2005 1:10 am    Post subject: Red horizontal lines on sony KV X2993B Reply with quote

Hello,
Thx for this advice.
I can't see any 1000V voltage on the RGB board schema ?
To test the driver / red gun can I swap the inputs (for instance red and blue) ?
Thx in advance.
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gary



Joined: 05 Apr 2005
Posts: 584
Location: MANCHESTER, uk

PostPosted: Tue Dec 06, 2005 1:16 am    Post subject: Reply with quote

JUDGING OFF THE FLARING YOU ALSO HAVE, I WOULD SAY THE CRT IS LOW EMMISION AND THAT THE AUTO GREY SCALE IS DRIVING THE CRT AS HARD AS POSSIBLE, MEASURE THE CATHODE VOLTAGES AND IF THE RED IS SIGNIFICANTLY LOWER THAT IS THE PROBLEM. I HAVE SEEN THIS ON SEVERAL OLDER SONY TVS IN THE PAST COUPLE OF YEARS
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micmoc
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PostPosted: Tue Dec 06, 2005 9:08 pm    Post subject: Red horizontal lines on sony KV X2993B Reply with quote

Hello Gary,

I'm not sure to understand the real cause of my problem : suppose red signal on cathode is too low, what is the problem ?
Thx for your reply.
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gary



Joined: 05 Apr 2005
Posts: 584
Location: MANCHESTER, uk

PostPosted: Tue Dec 06, 2005 9:27 pm    Post subject: Reply with quote

IF THE RED CATHODE VOLTAGE IS LOW THE PROBABLE CAUSE IS A U/S CRT, TO CHECK DISCONNECT ONE END OF THE RED CATHODE FEED RESISTOR AND ONE END OF THE BLUE CATHODE FEED RESISTOR, USE A WIRE TO LINK THE RED CATHODE FEED RESITOR TO THE BLUE CATHODE AND ANOTHER WIRE TO LINK THE BLUE FEED RESISTOR TO THE RED CATHODE, SO BLUE CIRCUIT NOW DRIVING THE RED AND VICE VERSA, IF YOU NOW STILL HAVE RED FLYBACK AND FLARING CRT NEEDS TO BE REPLACED.
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micmoc
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PostPosted: Tue Dec 06, 2005 9:40 pm    Post subject: Red horizontal lines on sony KV X2993B Reply with quote

Thx Gary, as quick as light Wink
It would be easier for me to swap blue and red wires on the INPUT connector of CRT board : is it ok for you ?
If the CRT would be used, could the image be OK for time to time (let's say 20s then several minutes KO, then OK again) ?
Thx, once more.
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gary



Joined: 05 Apr 2005
Posts: 584
Location: MANCHESTER, uk

PostPosted: Tue Dec 06, 2005 10:46 pm    Post subject: Reply with quote

NO, SWAPPING THE INPUT TO THE CRT BASE WOULD NOT PROVE IT AS THE RGB DRIVES WOULD STILL BE CONNECTED TO THEIR CORRESPONDING GUNS, IT NEEDS TO BE THE CATHODE FEED RESISTORS.
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