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Toshiba 50VJ23P 50" Rear Proj Screen Prob. Single line
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nlouks



Joined: 23 Jan 2007
Posts: 14

PostPosted: Tue Jan 23, 2007 3:49 pm    Post subject: Toshiba 50VJ23P 50" Rear Proj Screen Prob. Single line Reply with quote

Hi. Does anyone have an idea as to why I have a black screen with a single coloured horisontal line across the middle.

I have perfect sound.

I'm fairly good with electronics and have tried to take a look myself.

It maybe the IC LA7833 (vertical deflection output IC) but I'm unsure as to how to check it is doing its job.

Please help Sad

Thanks, Nik.
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minnie



Joined: 18 Aug 2005
Posts: 2880
Location: Hell

PostPosted: Tue Jan 23, 2007 8:56 pm    Post subject: Reply with quote

I don't know this specific model but the vertical IC is a good place to start. There should be a couple of electrolitic caps around it that should also be checked/replaced. The vertical IC should be about $4.00. If you replace it and it doesn't work, we can go from there.
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nlouks



Joined: 23 Jan 2007
Posts: 14

PostPosted: Wed Jan 24, 2007 6:59 pm    Post subject: Reply with quote

Thanks minnie. I have a replacement IC on its way. I'll Check the caps when i get the IC as my Multimeters battery has ran flat (doh) Embarassed

I'll get back as soon as I have fitted the IC.

Thanks again.
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nlouks



Joined: 23 Jan 2007
Posts: 14

PostPosted: Thu Jan 25, 2007 7:26 pm    Post subject: Nope not the IC Reply with quote

Sad Crying or Very sad changed it but it's not the IC.

I cant check the caps at the min.

Any other ideas.

Its just a solid horisontal bar of light across the middle of a black screen.

I can adjust the brightness and focus of each color on the front of the set but that's it.

Crying or Very sad
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R.J. - gast
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PostPosted: Thu Jan 25, 2007 8:43 pm    Post subject: Reply with quote

For the beginning check up a voltage of a feed on a microcircuit if it is absent or too low, check up ≈ 1-3 Ω resistors in area of the horisontal transformer.

I'm sorry for my laguage. Embarassed
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nlouks



Joined: 23 Jan 2007
Posts: 14

PostPosted: Thu Jan 25, 2007 10:24 pm    Post subject: Reply with quote

Thanks R.J. - gast.

I know what your saying.

Does anyone have a schematic for this TV so I can see what's supposed to be what?

Thanks,

Nik.

P.s. R.J. - gast Your english is pretty good.
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minnie



Joined: 18 Aug 2005
Posts: 2880
Location: Hell

PostPosted: Fri Jan 26, 2007 12:09 am    Post subject: Reply with quote

I don't but, off the flyback should be some diodes. The out put of the flyback should go thru a resistor that will open then to the diode to the vertical IC. Just back step from the vert ic to the diode to the resistor. If I can find a print I'll get more specific.
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nlouks



Joined: 23 Jan 2007
Posts: 14

PostPosted: Sun Jan 28, 2007 5:08 pm    Post subject: Reply with quote

The feed to the IC was missing. I'm sure when i checked it last, there was voltage. Anyway, traced back to a 5a board fuse on the power board.

Replaced 5a fuse and all is okay now apart from the screen burn from where the line was.

At least its working.

Anyone know how to get rid of or hide screen burn! Just the green.

Cheers, Nik.

P.S. thanks to MINNIE + R.J. - GAST for your help.

For anyone else with this problem - LA7833 needs the following voltages at these pins:

Pin 1. -15v
Pin 6. +15v

If there is no voltage at Pin 6, check board fuse Z858. It is a 5a board fuse that is usually white or possibly orange (looks a little like a resistor)

Check the continuity across the fuse. If no continuity soder in a new one![/b][/u]
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minnie



Joined: 18 Aug 2005
Posts: 2880
Location: Hell

PostPosted: Sun Jan 28, 2007 5:24 pm    Post subject: Reply with quote

Only way to get rid of burn in is replace the crt's that are effected. Not cost effective. Glad you got it! Cool
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nlouks



Joined: 23 Jan 2007
Posts: 14

PostPosted: Sun Jan 28, 2007 5:41 pm    Post subject: Reply with quote

Thought as much.

cheers minnie.
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