Tip & How-To about Televison & Video

How to find and replace a defective vertical IC.

When your TV works, has sound, good indicator light but all you have for a picture is a horizontal line across the screen, you have no vertical drive. This can be caused by the IC overheating or a power spike. In addition if you have a newer TV (projector) it may not turn on and will only blink an error code.

This is not a difficult fix but requires patience, good soldering skills and dilligence. Begin by unplugging the set and removing the rear lower area. Around the perimeter of the section you will see screws. Some will have arrows pointing at them. Remove all these screws and remove the rear cover.

Now you should be able to see the entire chassis. It will be mounted on a plastic frame and will consist of two or more circuit boards. The one, usually on the left, will be a small signal board. The one on the right will be the low voltage power supply, high voltage power supply and you guessed it, the vertical drive section.

The vertical IC is located near where the wires from the yoke which are red,green,yellow and blue terminate on the main board. The yoke is a large coil on the rear of the CRT which spreads the beam. It is slid over the glass CRT. Follow the wires (which should be green, yellow, blue and red to the circuit board. This will be the vacinity of the vertical IC. It will be mounted to a large heat sink and generally the designation begins with "LA" followed by 4 numbers. Panasonics generally begin with TDA.

Once located, remove and replace the unit. Removing the unit will probably require removing the circuit board. This involves removing all the screws around the perimeter of the board and any which you find in the center of the board. Do not force it, if it will not move easily look for and remove more screws.

You can get the replacement parts at http://www.encompass.com . Make sure you clean off the old heat sink compond and reinstall new heat sink silicone also available at the same web site. The heat sink compound facilitates heat transfer to the heat sink and keeps the IC cool. Generally the ICs are run at a high output and get very hot.

After replacement of the IC check all the safety resisters near it for continuity and also any and all diodes for integrity. These parts would be in the vicinity of the heat sink. Removing the IC may require prying it off the heat sink as many times the heat sink compound acts like a glue.

If everything checks ok you should have a working set.

If you do not have vertical drive, you will need a schematic to find the power source for the IC and test the circuit to see if it has the proper voltages.

You can sometimes get schematics from http://www.encompass.com but they do not have all of them. If you do not mind paying about $16.00 US you can get any service manual from http://www.servicemanuals.net .

Once the proper power is supplied to the IC you should have a working set.

Remember to use an isolation transformer anytime you are going to check voltages in the set. Modern TVs have the chassis attached to neutral making a 60 volt difference between the chassis and hot side. This means that if you do not use an isolation transformer and apply a DVM with a low path of resistance you will cause a direct short and blow the fuse, if you are lucky. Also remember to be careful when measuring voltages as there are lethal voltages in a TV when plugged in and running.

Thanks for using FixYa and for the great rating.

hardrocko

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1 Answer

No picture, only a horizontal line across the screen


Hi and welcome to FixYa,

Your described problem indicates failure at the vertical deflection circuitry. Almost always, this would be a defective vertical IC. In some instances, this could also be caused by the absence of Vcc (supply voltage) to the said IC. This is a relatively easy/quick repair. What would be more challenging is identifying the IC, removing it, and replacing. Replacement would be readily available from most electronics part stores including Radio Shack.

Good luck and thank you for using FixYa.

Feb 24, 2009 | Zenith Televison & Video

1 Answer

jvc av-32wf36--have sound no picture


A bright Horizontal Line indicates failure of teh Vertical deflection Circuits.
Get a competent Technician to have a look.

Nov 30, 2008 | JVC AV-27230 27" TV

1 Answer

jvc av-29ts2ek


It sounds like a vertical deflection problem. You mentioned you had a white HORIZONTAL LINE in the middle of the screen. If this line runs from left to right across the screen it's in Verticla deflection. If it runs from top to bottom, it's in Horizontal deflection. I am assuming the problem is a Vertical deflaecion problem. The repairs necessary are most likley to replace the vertical capacitors or the verticla deflection chip.
Good Luck
Ed
NC Electronic Mills, Wyo USA

Jan 05, 2008 | JVC TM-2703SU 27" TV

1 Answer

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yes it can still be fixed! the pop sound you've heard maybe came from a blown capacitor in the vertical deflection circuits. this symptom, sometimes called the tube light effect, it is characterised by a bright thin horizontal line across the middle of the screen. this symptom is caused by a breakdown in the vertical deflection circuit. hence maybe the trouble maybe in the vertical oscillator, amplifier or output circuits. but if all i have said is not clear to you, better bring it to a qualified tv technician. good luck!

Mar 10, 2007 | RCA E13309 13-Inch Diagonal XL-100 Color...

1 Answer

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this symptom, sometimes called the tube light effect, it is characterised by a bright thin horizontal line across the middle of the screen. this symptom is caused by a breakdown in the vertical deflection circuit. hence maybe the trouble maybe in the vertical oscillator, amplifier or output circuits. but if all i have said is not clear to you, better bring it to a qualified tv technician. good luck!

Mar 08, 2007 | Sanyo DS31590 31" TV

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