TV Horizontal flipping

[Roelescence]

Hi everyone,
Can you please help me identify electronic components related to V-hold? My TV, new model, its picture keeps flipping horizontally and I cant find v-hold on the remote control neither at the back of the tv, so I decided to troubleshoot the components but one problem is that I cant identify the components related to v-hold.
Please help
Thank you

 

[betwixt]

If you want an answer it would be useful to know what type of TV it is. Is it LCD, Plasma or CRT, what manufacturer, model number and approcimate age?

Brian.

 

[jeffrey samuel]

do post the schematic in concern that can be helpful

 

[Roelescence]

This is a CRT TV, a chinese new model of Tusonra

 

[betwixt]

You might have a chance then. LCD and Plasma TV don't scan in the same way as CRT and there almost certainly wouldn't be any control over the scan frequency.

Without a schematic it isn't possible to show you exactly what to adjust so you will have to follow these general guidelines:

Look at the neck of the CRT (the tubular section that pokes out backward from the bowl of glass). On it you will see an assembly of wire coils pushed up to the bowl. There will be two wires heading toward the horizontal scan transformer which is usually black and has one or two controls on it (normally "screen" and "focus") these are NOT the ones you want. The other two wires from the coil assembly are the vertical scan connections. Follow these back to the crcuit board and you will find the vertical output stage. Sometimes this is two power transistors, sometimes a power IC with a heatsink. The vertical oscillator will either be inside the IC or made of components very close to it. If there is a control you can adjust, it will be in that area.

Brian.

 

[Roelescence]

If the vertical drive is defective, will the texts on the menu screen display also be affected?
My TV picture flips vertically but the texts on the menu screen display don't flip together with the picture. Am I having a problem with the RGB and CRT? circuitry? Please help...it's been my fourth day of troubleshooting.
I have replaced the vertical drive but still the problem remains...

Thank you...

 

[betwixt]

The vertical drive scans whatever video is sent to the tube so it will effect all the picture. If your menu is staying still while the video flips, the problem isn't in the vertical drive circuits, it is in the sync separator circuit. A video signal contains several parts, one obviously is the picture information but there is also a synchronizing pulse at the end of each scan line and a string of them at the bottom of the picture. You can't see them on the TV, you need an oscilloscope to do that. It looks like the pulses at the bottom of the video are not resetting the scan to the top again as they should do and it is either starting prematurely or late so the image is displayed shifted up or down. I can't help with finding the fault but the place to start looking is in the early video stages where the sync pulses are picked out of the video signal.

Brian.

 

[Roelescence]

Is it OK to replace the main IC? I have checked its surrounding components and found no defects including the RGB Board on the CRT. This china tv's board is labeled ''Sanyo Board''.
Here are the pictures:


- - - Updated - - -

Is it OK to replace the main IC? I have checked its surrounding components and found no defects including the RGB Board on the CRT. This china tv's board is labeled ''Sanyo Board''.
Here are the pictures:

 

[betwixt]

If you can get a replacement it may be your only option. These ICs can be hard to get hold of though.

Brian.

 

[Tipu606]

these china kit tv sets sometimes have peculiar problems that cant be solved
What is the number written on top of the main IC?

 

[jeffrey samuel]

Try to replace the IC if other issues are absent some where there might be slight power leakage in dry soldered areas check if everything looks good then try to replace the IC

 

[Roelescence]

LA76931S is the number of the main IC

 

[jeffrey samuel]

there are several variations like LA76931S 7n** available is it the whole ic index no you posted

 

[Roelescence]

Yes there was 7N after the number,
By the way I resoldered its pins and at last! It works. Now another problem is that there are thin four lines above the picture, am I having problem with the vertical circuit?

 

[rfredel]

Hello Roelescene,

this looks like a fault of a electrolyt capacitor at the vertical final amp. This will be a IC at the graet heatsink. Look there for a capacitor very close to the IC. The capacitor will lost capacity.

Regards

Rainer

 

[Tipu606]

Please resolder the pins of the vertical output IC which may be a 7 pin single in line(SIL) having number STV9302A(not sure) or LA78040
this IC is connected to a heat sink
regards