Help solve this tv problem...
09-27-04, 12:19 PM
#1
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Help solve this tv problem...
So... what's up with this?
these blue horizontal lines used to only exist when i watched dvds through the svideo input. now the lines show up during normal television.
i have an antenna connected to the vcr which goes to the tv via a coax. the dvd player connects to the tv via svideo. all other connections run to the receiver.
the 32" GE tv sits in a cabinet. on top of the cabinet is a center channel speaker, which I would assume is magentically shielded. also, in the cabinet, there are two tiny magnets to keep the doors closed when they are closed. i have removed the speaker and the magnets and the lines are there.
to be honest, i've had this problem on my parents tv for a year or two, but we just now got a digital camera which allows me to post an image. any help is appreciated.
talton
these blue horizontal lines used to only exist when i watched dvds through the svideo input. now the lines show up during normal television.
i have an antenna connected to the vcr which goes to the tv via a coax. the dvd player connects to the tv via svideo. all other connections run to the receiver.
the 32" GE tv sits in a cabinet. on top of the cabinet is a center channel speaker, which I would assume is magentically shielded. also, in the cabinet, there are two tiny magnets to keep the doors closed when they are closed. i have removed the speaker and the magnets and the lines are there.
to be honest, i've had this problem on my parents tv for a year or two, but we just now got a digital camera which allows me to post an image. any help is appreciated.
talton
09-28-04, 10:39 AM
#2
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i also just tried taking a picture of the lone single tear of sadness rolling down my face, but i couldn't get it to focus.
this is an attempt at a bump.
this is an attempt at a bump.
09-28-04, 11:43 AM
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umm.... i would have to say that the problem lies in that .... you have an Unusable signal.
no help?...ok
1. you shouldnt assume that the center is shielded.. w most cheaper speakers they are not. Try moving the center... but that's not what is causing the lines.
2.
-looks like you might have a bad s-video input.. or bad output on the dvd player.. try connecting any other dvd player the same way.
-possibly deffective s-video cable
-also try connecting dvd player via RCAs..
no help?...ok
1. you shouldnt assume that the center is shielded.. w most cheaper speakers they are not. Try moving the center... but that's not what is causing the lines.
2.
-looks like you might have a bad s-video input.. or bad output on the dvd player.. try connecting any other dvd player the same way.
-possibly deffective s-video cable
-also try connecting dvd player via RCAs..
09-28-04, 12:02 PM
#4
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thanks for the response.
the unusable signal is b/c i had turned my dvd player off.
but in response to your post, if the s-video connection was faulty, would that also cause the lines to appear during normal tv watching that's fed to the tv through the antenna?
i will try out your suggestions though and see what happens. thank you.
the unusable signal is b/c i had turned my dvd player off.
but in response to your post, if the s-video connection was faulty, would that also cause the lines to appear during normal tv watching that's fed to the tv through the antenna?
i will try out your suggestions though and see what happens. thank you.
09-29-04, 01:48 AM
#5
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tried all that stuff. the lines are still there.
i asked my stepfather about and wires in the wall behind the tv that might cause interference, but he said that there's only one wire running in that wall which goes to a lamp.
any other possibilities or is it fubar?
i asked my stepfather about and wires in the wall behind the tv that might cause interference, but he said that there's only one wire running in that wall which goes to a lamp.
any other possibilities or is it fubar?
09-29-04, 08:16 AM
#6
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Those look like retrace lines. Try this:
and look at:
Adjustment of the brightness and contrast controls will usually fix this problem. However, if it persists and no combination of these controls will give satisfactory results, then locate the "black level" potentiometer, which is probably set too high, and adjust it accordingly.
11.13) Retrace lines in picture
During the time the electron beam is returning from right to left at the end
of a line and bottom to top (over the course of multiple lines), it is supposed
to be result in no visible light on the screen. However, a number of faults
can result in visible retrace lines.
The appearance will likely be a general reduction in contrast from the visible
horizontal retrace on every scan line and two dozen or so diagonal lines lines
(lower left to upper right) resulting from the vertical retrace.
The retrace lines may be either white or gray (possibly with a slight color
tint due to unequal settings of the color adjustments) or a primary color -
red, green, or blue. Anything in between is also possible but less likely.
11.14) White/gray retrace lines
Where all colors are involved - the lines are essentially white or gray (or
with a slight tint due to slight unequal settings of the color adjustments),
look for something common like an incorrectly adjusted screen (G2) or master
brightness/background/bias control or a problem in one of these circuits, a
defective power supply or a problem in the blanking circuitry:
* Screen (G2) or master brightness/background/bias control - mark setting and
then see if a slight adjustment removes the retrace lines. See the chapter:
"Monitor Adjustments". Of course, if this happened suddenly, the problem is
not due to a misadjusted control though a dirty pot is possible - turn it
back and forth - this might clean it and restore normal operation.
* Power supply or connection to CRT neck board - insufficient voltage will
result in the CRT never totally blanking. Check (usually scan derived)
power supply components (from flyback).
* General power supply - check B+ for correct value and ripple. A main power
supply fault might result in these symptoms (and usually many others).
* Blanking circuit - this may be a part of the video/chroma chip or separate.
Check waveforms to determine if the blanking pulses are making it to the
video output.
11.15) Red, green, or blue retrace lines
Where only one color is showing, suspect an incorrectly adjusted individual
background/bias control or bad part on the CRT neck board for that color.
* Individual brightness/background/bias control(s) - mark setting of pot for
the problem color and then see if a slight adjustment removes the retrace
lines. See the chapter: "Monitor Adjustments". Of course, if this happened
suddenly, the problem is not due to a misadjusted control though a dirty
pot is possible - turn it back and forth - this might clean it and restore
normal operation.
* Component or connection on CRT neck board - insufficient voltage to or
incorrect biasing of the video driver for this color can result in the
CRT never totally blanking. Compare voltages and signals, and swap
components between good and bad channels to confirm.
* Blanking circuit - this may be a part of the video/chroma chip or separate.
Check and compare waveforms of good and bad colors to determine if the
blanking pulses are making it to the video output.
There is a slight possibility that a bad CRT may result in visible retrace
lines. To eliminate this possibility:
* Disconnect the filament - all evidence of a picture, raster, and retrace
lines should disappear once the filaments/cathodes have cooled (15 seconds
or so. If there are still visible retrace lines, the CRT is suffering
from cold or field emission from someplace (may not even be the cathode).
* Turn down the screen (G2) control on the flyback (usually). If one color
remains no matter how you set the control, again there is some kind of
weird emission from the CRT. However, if white/gray retrace lines remain,
the problem may be in the screen supply.
See the section: "Bad CRT causing retrace lines".
11.16) Bad CRT causing retrace lines
(From: Jeroen H. Stessen ([email protected])).
The TV which I bought last started developing retrace lines after a month or
so of use. I took it back to the lab for warranty (special deal) and had it
examined by the real experts. They found that even with the filament supply
disconnected and VG2 at 0V the screen would still light up. They could even
see that the electrons weren't even coming from the cathode. That was with
only the picture tube in a test rig. So in this case the obvious conclusion
had to be that the tube was bad, and it was replaced (32" 16:9 SF, very $$).
It had something to do with processing problems during manufacturing of the
electron guns.
So even if this was a rare case, it *can* happen that retrace lines are due
to a bad picture tube. It's more usual to suspect the VG2 (screen voltage)
or a defect somewhere in the RGB video path.
During the time the electron beam is returning from right to left at the end
of a line and bottom to top (over the course of multiple lines), it is supposed
to be result in no visible light on the screen. However, a number of faults
can result in visible retrace lines.
The appearance will likely be a general reduction in contrast from the visible
horizontal retrace on every scan line and two dozen or so diagonal lines lines
(lower left to upper right) resulting from the vertical retrace.
The retrace lines may be either white or gray (possibly with a slight color
tint due to unequal settings of the color adjustments) or a primary color -
red, green, or blue. Anything in between is also possible but less likely.
11.14) White/gray retrace lines
Where all colors are involved - the lines are essentially white or gray (or
with a slight tint due to slight unequal settings of the color adjustments),
look for something common like an incorrectly adjusted screen (G2) or master
brightness/background/bias control or a problem in one of these circuits, a
defective power supply or a problem in the blanking circuitry:
* Screen (G2) or master brightness/background/bias control - mark setting and
then see if a slight adjustment removes the retrace lines. See the chapter:
"Monitor Adjustments". Of course, if this happened suddenly, the problem is
not due to a misadjusted control though a dirty pot is possible - turn it
back and forth - this might clean it and restore normal operation.
* Power supply or connection to CRT neck board - insufficient voltage will
result in the CRT never totally blanking. Check (usually scan derived)
power supply components (from flyback).
* General power supply - check B+ for correct value and ripple. A main power
supply fault might result in these symptoms (and usually many others).
* Blanking circuit - this may be a part of the video/chroma chip or separate.
Check waveforms to determine if the blanking pulses are making it to the
video output.
11.15) Red, green, or blue retrace lines
Where only one color is showing, suspect an incorrectly adjusted individual
background/bias control or bad part on the CRT neck board for that color.
* Individual brightness/background/bias control(s) - mark setting of pot for
the problem color and then see if a slight adjustment removes the retrace
lines. See the chapter: "Monitor Adjustments". Of course, if this happened
suddenly, the problem is not due to a misadjusted control though a dirty
pot is possible - turn it back and forth - this might clean it and restore
normal operation.
* Component or connection on CRT neck board - insufficient voltage to or
incorrect biasing of the video driver for this color can result in the
CRT never totally blanking. Compare voltages and signals, and swap
components between good and bad channels to confirm.
* Blanking circuit - this may be a part of the video/chroma chip or separate.
Check and compare waveforms of good and bad colors to determine if the
blanking pulses are making it to the video output.
There is a slight possibility that a bad CRT may result in visible retrace
lines. To eliminate this possibility:
* Disconnect the filament - all evidence of a picture, raster, and retrace
lines should disappear once the filaments/cathodes have cooled (15 seconds
or so. If there are still visible retrace lines, the CRT is suffering
from cold or field emission from someplace (may not even be the cathode).
* Turn down the screen (G2) control on the flyback (usually). If one color
remains no matter how you set the control, again there is some kind of
weird emission from the CRT. However, if white/gray retrace lines remain,
the problem may be in the screen supply.
See the section: "Bad CRT causing retrace lines".
11.16) Bad CRT causing retrace lines
(From: Jeroen H. Stessen ([email protected])).
The TV which I bought last started developing retrace lines after a month or
so of use. I took it back to the lab for warranty (special deal) and had it
examined by the real experts. They found that even with the filament supply
disconnected and VG2 at 0V the screen would still light up. They could even
see that the electrons weren't even coming from the cathode. That was with
only the picture tube in a test rig. So in this case the obvious conclusion
had to be that the tube was bad, and it was replaced (32" 16:9 SF, very $$).
It had something to do with processing problems during manufacturing of the
electron guns.
So even if this was a rare case, it *can* happen that retrace lines are due
to a bad picture tube. It's more usual to suspect the VG2 (screen voltage)
or a defect somewhere in the RGB video path.
09-29-04, 11:23 AM
#7
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thank you aguynamedmike
so... do you know where the potentiometer is? playing with the brightness and contrast controls did nothing.
and for all the other stuff, that looks like it requires me to open up the tv, right? if so, are there any precautions i should take before opening it up? thanks again.
so... do you know where the potentiometer is? playing with the brightness and contrast controls did nothing.
and for all the other stuff, that looks like it requires me to open up the tv, right? if so, are there any precautions i should take before opening it up? thanks again.
09-29-04, 11:49 AM
#8
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most of the time you dont have to open th TV... search the web for how to get in to the service menu for your particular set... (usualy done but pressing a combination of RC buttons) once you'll find that info, the same site should tell you which parameters are which.
09-29-04, 12:28 PM
#9
Administrator
I've adjusted a pot inside my set (some are accessible from outside) that affected that very thing.
But I'm mostly here to warn you against getting inside your TV. The high voltages that can kill you will remain there even after you've unplugged the set. I treat touching stuff on the inside of a TV like sticking my hand into a cobra cage.
But I'm mostly here to warn you against getting inside your TV. The high voltages that can kill you will remain there even after you've unplugged the set. I treat touching stuff on the inside of a TV like sticking my hand into a cobra cage.
09-29-04, 12:35 PM
#10
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Originally posted by X
I've adjusted a pot inside my set (some are accessible from outside) that affected that very thing.
I've adjusted a pot inside my set (some are accessible from outside) that affected that very thing.
09-29-04, 12:52 PM
#11
Administrator
It totally varies by set. You could start by looking for some small knobs or adjustments with slots for a screwdriver on the back of your set. Newer sets could have that adjustment in the service menu.
Frankly, looking at your picture with the pincushioning, hearing that the problem is spreading, and especially that the set is a GE, I'd consider getting a new set.
Frankly, looking at your picture with the pincushioning, hearing that the problem is spreading, and especially that the set is a GE, I'd consider getting a new set.
09-29-04, 12:53 PM
#12
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Originally posted by Oraphus
most of the time you dont have to open th TV... search the web for how to get in to the service menu for your particular set... (usualy done but pressing a combination of RC buttons) once you'll find that info, the same site should tell you which parameters are which.
most of the time you dont have to open th TV... search the web for how to get in to the service menu for your particular set... (usualy done but pressing a combination of RC buttons) once you'll find that info, the same site should tell you which parameters are which.
there were two sets of instructions i found. one which had me start with the tv off, the other with the tv on, but neither seem to work.
09-29-04, 03:26 PM
#13
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Originally posted by X
It totally varies by set. You could start by looking for some small knobs or adjustments with slots for a screwdriver on the back of your set. Newer sets could have that adjustment in the service menu.
Frankly, looking at your picture with the pincushioning, hearing that the problem is spreading, and especially that the set is a GE, I'd consider getting a new set.
It totally varies by set. You could start by looking for some small knobs or adjustments with slots for a screwdriver on the back of your set. Newer sets could have that adjustment in the service menu.
Frankly, looking at your picture with the pincushioning, hearing that the problem is spreading, and especially that the set is a GE, I'd consider getting a new set.
i appreciate the help. i'll talk to my parents about getting them a new tv.
