TV shows stripes/lines at the top of the screen - Electronic Circuits Projects Diagrams Free

Almazick · 11th June 2006, 06:12 AM

Hello!
I have Panasonic TV about 1 year old. It was working great til a few weeks ago, now it shows stripes/lines at the top of the screen that used to get better after tv was getting warm. Now I got more stripes/lines at the top of the screen and they don't dissapear even when tv gets warm. I removed the tv rear cover and found only 2 knobs for Focus and Screen and they won't solve the problem. I tried to adjust Var Resistor and again nothing. What can I do? What should I check for? Please help.

Thanks,

Russell
www.tvnorthshore.com

Don Hawley · 11th June 2006, 06:31 AM

If it is only a year old call distributor you got it from then Panasonic and ask them what the HECK goes they should cover the product. It's only one year old.

**Nigel Goodwin** · 11th June 2006, 08:43 AM

Quote:

Originally Posted by Almazick

Hello!
I have Panasonic TV about 1 year old. It was working great til a few weeks ago, now it shows stripes/lines at the top of the screen that used to get better after tv was getting warm. Now I got more stripes/lines at the top of the screen and they don't dissapear even when tv gets warm. I removed the tv rear cover and found only 2 knobs for Focus and Screen and they won't solve the problem. I tried to adjust Var Resistor and again nothing. What can I do? What should I check for? Please help.

For a start you might consider filling your location IN?, then people know where you are, TV's are fairly different depending where you are.

From your vague description it 'may' be frame flyback lines you can see?, or even teletext lines? - but that would depend on where you are?.

raybo · 11th June 2006, 09:25 AM

it is the horizontal coil that you can adjust or your bright and contrast are not right they are det too high.

**Nigel Goodwin** · 11th June 2006, 10:00 AM

Quote:

Originally Posted by raybo

it is the horizontal coil that you can adjust or your bright and contrast are not right they are det too high.

The two adjustments he's refering to are the focus and A1 (screen) controls, these are usually part of the LOPTX - often these are the only manual adjustments in a TV set, the rest are done using an "electronic screwdriver", with the adjustments stored in the on-board EEPROM.

zevon8 · 11th June 2006, 12:55 PM

Sounds like maybe the vertical sweep is not linear. Combine that with the "got better after it warmed up" and it sounds like either the DC for the vertical chip is saging from a bad electrolytic, or the vertical IC feedback electrolytic is bad. Possibly just bad solder joints around the vertical IC, but sounds more like a bad capacitor. The DC power for the vertical section could come from the LOPT, so the cap would likely be near that, not the vertical IC.

This produces a vertical sweep ramp signal that is curved, instead of flat, stretching out the picture at the top.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

11th June 2006, 06:12 AM	(permalink)
Almazick	TV shows stripes/lines at the top of the screen Hello! I have Panasonic TV about 1 year old. It was working great til a few weeks ago, now it shows stripes/lines at the top of the screen that used to get better after tv was getting warm. Now I got more stripes/lines at the top of the screen and they don't dissapear even when tv gets warm. I removed the tv rear cover and found only 2 knobs for Focus and Screen and they won't solve the problem. I tried to adjust Var Resistor and again nothing. What can I do? What should I check for? Please help. Thanks, Russell www.tvnorthshore.com

11th June 2006, 06:31 AM	(permalink)
Don Hawley	If it is only a year old call distributor you got it from then Panasonic and ask them what the HECK goes they should cover the product. It's only one year old.

11th June 2006, 09:25 AM	(permalink)
raybo	it is the horizontal coil that you can adjust or your bright and contrast are not right they are det too high.

11th June 2006, 12:55 PM	(permalink)
zevon8	Sounds like maybe the vertical sweep is not linear. Combine that with the "got better after it warmed up" and it sounds like either the DC for the vertical chip is saging from a bad electrolytic, or the vertical IC feedback electrolytic is bad. Possibly just bad solder joints around the vertical IC, but sounds more like a bad capacitor. The DC power for the vertical section could come from the LOPT, so the cap would likely be near that, not the vertical IC. This produces a vertical sweep ramp signal that is curved, instead of flat, stretching out the picture at the top.