Red horizontal lines on sony KV X2993B

micmoc · Guest

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.

Guest · Posted: Mon Dec 05, 2005 12:10 am Post subject:

Did You check the Power Supply? (for example quality of voltage)

Guest · Posted: Mon Dec 05, 2005 5:44 am Post subject:

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

guest2 · Guest

Too high screen voltage, or weak CRT. Set the Screen voltage on the CRT board.

micmoc · Guest

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.

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

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

micmoc · Guest

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.

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

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.

micmoc · Guest

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.

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

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.