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[Moved]: LG CRT TV ROLLING DOWN

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SHIVAKUMAR K

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Dear Friends,

I have LG FLATRON CRT TV, the picture is rolling down. what to do ? its not standing center, its going down. I changed some e-capacitors, but no use. If i change the Vertical IC, the problem will solve? or what to do? Thanks to all in advance........
 

Is this an old-fashioned tv? Look in the back for openings where there should be adjustments for vertical, horizontal, brightness, contrast, etc. If you're lucky you can do it with a screwdriver. Or else you might need a hex-shaped tool (Allen wrench).

Normally the tv circuitry is supposed to detect a break after each broadcast frame. Then it starts a new frame. That's how it is synchronized. It needs to be very sensitive to the break, but sometimes it misinterprets the signal, so you get rolling of the picture.
 

No Sir,

It's not so old TV 2010 model, i searched adjustments near crt board and main board. but it's not there. I think the problem will be vertical sync lost, If I change the verical IC will be any improvement? please help me friends. I have attached the image, the second one is my problem. Picture9.png
 

If your horiz sync is fine, then you need to see the output from the tuner module. Most likely it will be a plug in module and see if you can locate any pot for gain.
 

You Mean should i check the vertical adjustment in tuner ? Or should i change the tuner ?
 

It is impossible to say; you may remove it, dust it and put it back and it may work again like new. It might be a contact problem, some capacitor or loose contact, or some other fault. The video coming from the tuner will be decoded by the TV into several components.

By the way, if the cable channels are playing ok, then most likely it is the tuner fault.
 

Actually, we are not (TV mode) using the tuner for input video, we are using the av mode, but the picture is moving down.....
 

SHIVAKUMAR K said:
Actually, we are not (TV mode) using the tuner for input video, we are using the av mode, but the picture is moving down.....
Click to expand...

Most likely you are bypassing the tuner and the problem lies on somewhere later. You can search for a pot marked V-hold and try to adjust that one. It will be on the main board.
 

Thanks Mitra,

I searched very well the v-hold adjustable preset on main board and crt neck board but, it is not anywhere.... i connect DVD player also, the problem is same, picture is jumping, rolling and going down.... should i change the Micro IC or vertical IC ? (Because some one said to change both IC) Please help me......
 

Can you please post a photo of the main board?
 

Ok Sir,

I will post the photo of main board tomorrow, For What purpose Sir? You would like to see the preset of v-hold pot? I searched in main board Sir. But it is not there Sir. There are vertical IC, HOT, Amplifier IC, Sub Woofer IC, Memory Ic and Micro-controller IC (The jungle IC). but there is no any adjustable preset. Anyway thanks for your help Sir, I'll post the photo tomorrow...
 

I believe that one of the outputs of the "jungle IC" is responsible for the vertical hold. If the output is valid, then some capacitor in the chain has gone bad. Usually the electrolytic capacitors are most vulnerable and go bad first. Please also search of an electrolytic capacitor with swollen top.
 

Dear Sir,

I have attached the photo of the Main board, please have a look and suggest me what to do ? These photos taken by Mobile, the picture will not be clear, sorry for that and thanks for your help.... Main 1.jpgmain 2.jpgMain board.jpgMain.jpg
 

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It is impossible to make out anything. Please remove the ICs from the sockets and vacuum the board with a vacuum cleaner and replace the ICs. Look for cold solder and etc.
 

Thanks for your help mitra,

I'll do re-solder the all the dry joints and clean the IC as you said, If the problem will not solve after doing this method then what to do ? should I change all the small caps near the IC or Should I change the IC ? Should I change Memory IC ? or any other suggestion ?
 

The power ICs are mostly mounted on the CRT socket itself: both X-Y drives in a TV are magnetic. You need to follow the cables that are going to the coils mounted on the neck. They are driven by power transistors commonly mounted on the CRT socket itself.

The memory IC is not the problem. In fact, it is working fine.
 

Thanks Brother,

Memory IC will not the problem ? !!!! Then what to do now Sir, I already replaced the CRT Neck IC, Now I am talking about The Main IC (Motherboard IC) , should I change or should i change the all e-caps near that IC, please help...
 

Rolling down is usually one of two problems. Either the vertical sync is not getting to the main IC or the master oscillator is off frequency determined by the crystal next to it. That shiny metal can looks rusty in your photo? What is the part number on the main IC? Does the crystal have a frequency stamped on it? I assume this is a PAL television, not NTSC? The horizontal and vertical scan frequencies are divided down from the master oscillator so if it is off frequency a small amount, usually the raster rolls vertically. You can try putting an ice cube in a double ziplocked bag to touch the crystal and cool it. See if the rolling stops or changes.

Larry G
 

Thank you Sir,

I understand what are you coming to say, I want to check the crystal or i want to replaced with new one. where form vertical sync will getting to the main IC ? The main IC Number is TDA9367PS/N2/5I , thanks for your reply....
 

I've attached a link for the TDA9367 pdf. Everything happens in that IC, video detection, the sync separation and the decision for PAL or NTSC. Does the video look ok, just rolling? Try cleaning very well the pins of the IC and the crystal leads, even removing crystal to clean if necessary. Problem is either the crystal or that IC. It is a countdown circuit for vertical frequency from that crystal frequency. Hmmm, I don't see how to attach a pdf. It is here: https://www.datasheet4u.com/pdf/TDA9367-pdf/856318 Scroll down to where it says download pdf
 

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