My Sanyo tv Model CM21MX8ZCA has a vertcial scan problem.As the set warms up it reaches +- 3/4 screen size.Changing the vertical IC LA 78040AN does not rectify problem.Please help.

Check and replace its main system control memory IC; with the same number. http://electronicshelponline.blogspot.com/

Vertical scan output circuit fault. In most cases, it will be the fault with the vertical scan out IC.
If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/

Replacing vertical output IC won't poise this type of problem. Check the voltages at the audio output section.

Hello
The vertcial output section in your TV is faulty. It may be either to a voltage loss to that section or an IC failure. Normally IC in this section will fail in most of the tVs. Vetical output IC can be located on the main board of your TV, normally screwed on to a metal heatsink to radiate heat from it while working. Locate this IC, and resolder all of its solder terminals by applying a little more solder, wthout making any solder bridge short in between adjecent solder terminals. If ther is any loose soldering, it will be cleared out. If this does not helps you measure the voltage that comes to that IC. If this is also found normal replace the IC. OK.

Hello
You haven't specifed nothing about the model number or brand name of your flat panel teleivison. i assumes that it to be a picture tube based one and posts this solution before you.
A thin horizontal line across the screen with sound output is OK, is the sympton of total failure of vertical sweep. This may be due to failure of vertical output IC or loose solder terminals of that IC. The vertical output IC will heat up while working, and repeated heating and cooling may make its solder terminals to get loose. Just open your TV, pull out the board that contains vertcial output section, turn it upside down, resolder all the solder terminals of that IC by applying a little more solder, without making any solder bridge in between terminals. Check the voltage to the vertical output IC also. If this resoldering method does not help you, replace the vertical IC itself with same type and number will solve your TVs problem. OK.

Hello
It is reparable problem. You see a blue line across the middle of the screen I thinks and posts this solution. The fault is due to the absence of vertical scan. In your set, there is an IC used for this purpose, and it has been dead short now. That is why you see the line at the begining, and it disappears a few minutes after. The vertcial output IC can be located at the main printed circuit board, usually screwed on to a metal heatsink to sink away the heat genereted in it while working. You can easly located it by the following method.
Look at the deflection coil, the coil fitted at the neck of the picture tube. From which, four wire will go towards the printed circuit board, and will be pluged on to it with socket. Just draw out the printed circuit board from the TV and turn it upside down. Look for the connections that I have menttioned earlier, four of them, out of which two of them will be for horizontal scan, and two of them will meant for vertical scan. Follow the vertical scan track, can be identified by two wires emerges form the board, will be connected via copper track and will go to the vertical section, from which you can identify the vertical IC fitted neareby it, usually will have 7 or 9 pin vertical type one.
There is no need to check it now, because, it has already been shorted and damaged in your TVs present case. Desolder it out from the board, and go for a new one of same type and number, replace it as the previous IC was, will solver your proble.
You must have a desoldering pump, a soldering Iron, solder wire, some knoledge in electronics,and more comecentration and patience. OK.

Hello

The vertical scan of your TV has failed. All picture tube type TVs have both horizontal and vertical scan sections to scan the picture on the secreen. When horizontal scan fails, you will see a vertical line at the middle of the screen, and if vertical scan fails, there will be a horizontal line through the middle of the screen. In your TV, the second stated has happened.
This may be due to an IC trouble or a voltage loss inside the printed circuit board of your TV. To rectify this fault you have to open your TV, and locate the vertical output section inside it. It is very easy to locate that section. There will be four wires goes from the deflection yoke; the coil fitted at the neck of the picture tube; out ot which, two will be thick and the other two will be thin. The thick wires are usually colour coded as red and blue. Colour coding may differ from set to set. Anyway you have to follow the tow thin wires, as they are carrying vertical scan signal to the yoke.
Following it, you will reach to a plug in point on the printed circuit board. Upside down the printed circuit board, and follow the track through which that wire connection goes, and finally you will reach to the vertical output section.
There may be transistors or IC used on that section. First check the voltage at the vertical output section. Voltage lose also may occur in this section. If it uses IC, check for any loose or bad solderings at the terminals of the IC. I advice you to resoder the suspected points by applying a little more solder, without shorting the terminals. In most cases this will solve the problem. If there is voltage, and there is no loose solderings and still the fault perists, replace the IC or transistors, whatever it may be, with same type and number.
If you want anymore asistance, fee free to contact me through Fixya. OK.

i have had this type of problems,
check the electrolitic capacitor, charge, if it does not improve change a verticle ic.

I don't have any specific information on this model.... but I can tell you that the problem is the vertical deflection IC or just the solder connections on the PC side of the IC. The part number usually starts with the letters LA and then 4 numbers. Will be on a metal heat sink. And sometimes there is a 1ohm resistor that opens and even the diode may be bad in that circuit coming off of the HV transformer through the resistor and then the diode then to the vertical IC Hope this helps.

Set has a bad vertical sweep IC. Also This Sanyo has a tendancy , when the IC blows out , to take the fusable resistor in the sweeo supply that feeds the vertical IC. This set should only be serviced by a trained technician because of ther high Voltage that lingers within. This repair should run you antwhere from 85.00 to 150 bucks. Good Luck