Brightness problem, JVC AV-27230 27" TV

[Thor]

I have a JVC AV-27230 that of late has started to turn on rather bright, it goes
down to less but still too bright later(unknow time , maybe 10-20 minutes or
so).
I have the brightness control set near minimum, same for picture slider on the
on screen controls.
When the set is initially turned on there are also a set(2) of dashed horizontal
lines almost all the way across the very top of the screen, these vary in color
from nearly white to a yellow green. These lines across the screen eventually
settle down to two dashes single line in the upper left corner.

The high brightness is there when the TV is set to a blank input but the
horizontal lines are not. A blank input is Video1 and I have nothing connected
to that.
Same high brightness when playing a dvd along with the horizontal lines, Video3
input.

After the "warm up" the horizontal lines shorten to two or three short segmented
dashes and are only about one scan line thick, but not across the entire top of
the screen. These line sit in the upper left corner and change colors from time
to time. As I said I have the brightness slider almost all the way down, where
it shouldn't have to be. I thought it was data coming from the cable but that is
wrong if I have the same problem when looking at a different input.

With my crappy description does any one have any idea of where to look for what
is going wrong with the set? A cap going bad maybe? I don't have a schem to this
TV.

BTW, the sound is ok, it /may/ be getting louder but I am not positive on this.
With that added it sounds like something in the power supply but I don't know
what.

Ask if you need more or better info.

Thanks for any help.


Thor

 

[AJ]

Problems in the g2 supply to the crt, Confirm level changes when adjusting
the screen control on the lopt. Lines [at top of screen only] probably
indicate fault in vertical frame defelction circuits, s.a. defective
electroltics, etc.
Also check your video processing and output circuits.

 

[Thor]

Problems in the g2 supply to the crt, Confirm level changes when adjusting
the screen control on the lopt. Lines [at top of screen only] probably
indicate fault in vertical frame defelction circuits, s.a. defective
electroltics, etc.
Also check your video processing and output circuits.

I have a JVC AV-27230 that of late has started to turn on rather bright, it
goes
down to less but still too bright later(unknow time , maybe 10-20 minutes
or
so).
I have the brightness control set near minimum, same for picture slider on
the
on screen controls.
When the set is initially turned on there are also a set(2) of dashed
horizontal
lines almost all the way across the very top of the screen, these vary in
color
from nearly white to a yellow green. These lines across the screen
eventually
settle down to two dashes single line in the upper left corner.

The high brightness is there when the TV is set to a blank input but the
horizontal lines are not. A blank input is Video1 and I have nothing
connected
to that.
Same high brightness when playing a dvd along with the horizontal lines,
Video3
input.

After the "warm up" the horizontal lines shorten to two or three short
segmented
dashes and are only about one scan line thick, but not across the entire
top of
the screen. These line sit in the upper left corner and change colors from
time
to time. As I said I have the brightness slider almost all the way down,
where
it shouldn't have to be. I thought it was data coming from the cable but
that is
wrong if I have the same problem when looking at a different input.

With my crappy description does any one have any idea of where to look for
what
is going wrong with the set? A cap going bad maybe? I don't have a schem
to this
TV.

BTW, the sound is ok, it /may/ be getting louder but I am not positive on
this.
With that added it sounds like something in the power supply but I don't
know
what.

Ask if you need more or better info.

Thanks for any help.


Thor

I got rid of the lines. I replaced caps 424 and 425, feeding power to an amp in
the vertical section.

Next is to determine if the high brightness is actually in the set or if it is
just the way cable has their channels setup. Some channels look just fine, some
are on the dim side and others are rather bright. The cable company may have the
analog channels out of order to get people to buy into the more expensive
digital, it's a thought.


Thanks for the help,
Thor

 

[AJ]

No bother, glad the info assisted in repair of the vert frame circuit pbm.
Cheers.

Problems in the g2 supply to the crt, Confirm level changes when adjusting
the screen control on the lopt. Lines [at top of screen only] probably
indicate fault in vertical frame defelction circuits, s.a. defective
electroltics, etc.
Also check your video processing and output circuits.

I have a JVC AV-27230 that of late has started to turn on rather bright,
it
goes
down to less but still too bright later(unknow time , maybe 10-20
minutes
or
so).
I have the brightness control set near minimum, same for picture slider
on
the
on screen controls.
When the set is initially turned on there are also a set(2) of dashed
horizontal
lines almost all the way across the very top of the screen, these vary
in
color
from nearly white to a yellow green. These lines across the screen
eventually
settle down to two dashes single line in the upper left corner.

The high brightness is there when the TV is set to a blank input but the
horizontal lines are not. A blank input is Video1 and I have nothing
connected
to that.
Same high brightness when playing a dvd along with the horizontal lines,
Video3
input.

After the "warm up" the horizontal lines shorten to two or three short
segmented
dashes and are only about one scan line thick, but not across the entire
top of
the screen. These line sit in the upper left corner and change colors
from
time
to time. As I said I have the brightness slider almost all the way down,
where
it shouldn't have to be. I thought it was data coming from the cable but
that is
wrong if I have the same problem when looking at a different input.

With my crappy description does any one have any idea of where to look
for
what
is going wrong with the set? A cap going bad maybe? I don't have a schem
to this
TV.

BTW, the sound is ok, it /may/ be getting louder but I am not positive
on
this.
With that added it sounds like something in the power supply but I don't
know
what.

Ask if you need more or better info.

Thanks for any help.


Thor

I got rid of the lines. I replaced caps 424 and 425, feeding power to an
amp in
the vertical section.

Next is to determine if the high brightness is actually in the set or if
it is
just the way cable has their channels setup. Some channels look just fine,
some
are on the dim side and others are rather bright. The cable company may
have the
analog channels out of order to get people to buy into the more expensive
digital, it's a thought.


Thanks for the help,
Thor

 

[Dan K]

Take a look at this thread:

http://icrontic.com/forum/showthread.php?t=19549

It tells you how to adjust the G2 voltage by changing the value in the flash
and then re-writting the flash in the monitor. I got two Dell P991's fixed
this way. 1st thing to check is if your monitor is on the list of monitors
that will work with this method.

Dan