I have an old mitsubishi TV model cs 35203 serial 515512, and all that shows up on the screen is a thin horizontal line through the middle.

You can visit the Mitsubishi site but as this is a old set----Also try to Google that model number with "manual" to see if you can locate one.

you didn't mentioned if it is a horizontal line but i think it is.
It seems that you have a faulty vertical I.C. that scan vertical line.Because you it is defective you've lost the vertical scanning thats why you have only a horizontal line on the screen.

You will confirm it by powering on the unit with your cable signal present.When the sound is present on every channel it is confirm that you have a problem on the vertical section. You must look for a qualified technician to solve the problem....

Hello

Total Vertical Sweep failure had occured in your TV. That is there is only horizontal sweep there, and the whole picture sweeps horizontally and you see a horizontal nice line across the screen, at the middle of it. In this case, all other buttons will work, and sound output will be Ok.

This fault is normally due to Vertical Sweep Out Ic trouble. You have to open the back cover of your TV, and have to pull the main board out. Locate the Vertical Output Ic. It is easy to locate it. There will be four wires going to the deflection yoke assembly [the coil fitted alongwith the picture tubes' neck]. Amoung them, two will be thick, and is carrying horizontal sweep signals. The other two wire are comming from vertical sweep section. Follow the wires and find out from where it comes from the main board. Somewhere near it orginates from the main board, you will see an Ic usually screwed into a heat sink [ a metal plate or so]; and it is vertical output Ic.

Check first, whether there is input voltage [working voltage] come to it or not. Sometimes an open resistor problem may occur to show this fault. Normally vertical section will have a voltage rating between 18 to 35VDC. If that voltage is there, surely the Ic said above is damaged. Screw it out and desolder it from the mainboard, and go for an identical type and number, replacing it will solve your problem.

Take all precautions when we works with an elctrical equipment. Keep away children and never allow even stand beside you while you are working, and let an adult beside you as a precaution. Never use metal chair. Do wear a plastic of rubber shoes. If can, keep matted the floor also with carpet. Ok
Wish you success.
Gopakumar G.

Yeah, thats the tube, buy a new one. It's 15 yo anyway, let it go ;) Best of luck!!

The problem is in the vertical section of the main board. Bad capacitors and maybe the vertical IC. If you are not inclined to be a tech you will have to take it to a shop.. I don't know what they may charge but I normally get $69- $89

I was just watching TV and all of a sudden the screen minimized down to a single green line spanning across the screen horizontally. The label in the back says it was made in 1996 so it is an old tv. Can anyone help?

That sounds like vertical failure. Does the blue line run across the screen from side to side? Try resoldering the vertical output IC and see if that straightens it out. This is sometimes been a problem with that chassis. Let me know how you make out or if you need additional help.

Problem in the vertical deflection circuit. Possibly the vertical output IC

is locked and forgot my 4 digital code number

Replaced vertical IC ( la78041 ??>.. Or La78040 ). Look for born resistor beside IC. Replaced capacitor 100uf 35V too!!! Good luck !!