| Author |
Message |
Prosonman
Guest
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 Posted:
Mon Feb 07, 2005 10:55 am Post subject:
Sony KV-25K5U (FE-1) Problem |
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Hi All,
I'm an electronics engineer but know very little about T.V repair and was
hoping someone out there may be able to point me in the right direction to
fixing a problem with my T.V.
The problem or problems may be connected, firstly the picture quality has
become quite poor, in that it is no longer a sharp picture but I would say
out of focus particularly on the sides. This is very apparent on writing on
the screen that is virtually illegible and appears to have like a red
ghosting effect on every letter.
The other problem is a brightness problem, it may sound obvious but it gets
brighter when the image on screen has a lot of white in it, even the writing
on screen becomes clearer. For example on a news channel there is a band at
the bottom of the screen giving information, most of the time I find this
hard to read but when the picture above goes to a nice bright outdoor scene
suddenly the writing becomes legible, not perfect but at least I can be read
it.
The T.V is a Sony KV-25K5U that I believe is also called an FE-1, I don't
know if the problem is a faulty tube, a poor HT or bad power supply. Any
help would be greatly appreciated and where to get circuit diagrams would be
helpful.
Many thanks
Richard.
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Prosonman
Guest
|
| Posted:
Mon Feb 07, 2005 3:23 pm Post subject:
Re: Sony KV-25K5U (FE-1) Problem |
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Hi Jerry,
Thanks for taking the time to reply, I really appreciate it. I was hoping
someone might just say change Cxxx capacitor and your troubles will be over.
Will probably seek help with this one although I'm fairly familiar with the
safety issues, funny everyone elses TV I get asked to fix always seems to be
something easier, ie a dry joint, open circuit resistor or blown fuse. When
it comes to my own TV it always proves more difficult.
Many many thanks
Richard.
"Jerry G." <jerryg50@hotmail.com> wrote in message
news:36pdqaF55glm8U2@uni-berlin.de...
| Quote: | It sounds like the CRT is getting weak and is having less beam current.
When
there is lower beam current, it is very common to loose some beam focus
sharpness on the sides. As the contrast is increased, the beam focus will
get less sharp from the respective weak colour guns in the CRT. According
to
your description, I would assume the red colour gun to be getting weak.
Also, when there is a weak colour gun, the colour tracking between the
guns
starts to become non linear in relation to each other. This is what makes
the pictures seem to change their colour shading at different brightness
levels.
You can verify things if you like. You will need the shop service manual,
an
HV probe, DVM, and a scope. You can then follow up on the power supply,
high
voltage, horizontal drive pulses, video drive signals to the CRT elements,
focus supply, screen supply, and CRT voltage biases, according to the
references in the service manual.
An experienced TV service tech is used to this type of work. Even though
you
are an electronics engineer, TV servicing is specialized work, and
experience as well as a basic knowledge of television equipment is
necessary
to be productive in a practical sense.
It would probably be better for you to bring the set to a service centre.
and for the few dollars, they can verify all of this for you.
When working in these TV sets there are also some very serious safety
issues, especially when testing the HV, and working in the CRT bias area.
--
Jerry G.
======
"Prosonman" <prosonman@hotmail.com> wrote in message
news:cu7hf0$bf6$1@sparta.btinternet.com...
Hi All,
I'm an electronics engineer but know very little about T.V repair and was
hoping someone out there may be able to point me in the right direction to
fixing a problem with my T.V.
The problem or problems may be connected, firstly the picture quality has
become quite poor, in that it is no longer a sharp picture but I would say
out of focus particularly on the sides. This is very apparent on writing
on
the screen that is virtually illegible and appears to have like a red
ghosting effect on every letter.
The other problem is a brightness problem, it may sound obvious but it
gets
brighter when the image on screen has a lot of white in it, even the
writing
on screen becomes clearer. For example on a news channel there is a band
at
the bottom of the screen giving information, most of the time I find this
hard to read but when the picture above goes to a nice bright outdoor
scene
suddenly the writing becomes legible, not perfect but at least I can be
read
it.
The T.V is a Sony KV-25K5U that I believe is also called an FE-1, I don't
know if the problem is a faulty tube, a poor HT or bad power supply. Any
help would be greatly appreciated and where to get circuit diagrams would
be
helpful.
Many thanks
Richard.
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Jerry G.
Guest
|
| Posted:
Mon Feb 07, 2005 8:51 pm Post subject:
Re: Sony KV-25K5U (FE-1) Problem |
|
|
It sounds like the CRT is getting weak and is having less beam current. When
there is lower beam current, it is very common to loose some beam focus
sharpness on the sides. As the contrast is increased, the beam focus will
get less sharp from the respective weak colour guns in the CRT. According to
your description, I would assume the red colour gun to be getting weak.
Also, when there is a weak colour gun, the colour tracking between the guns
starts to become non linear in relation to each other. This is what makes
the pictures seem to change their colour shading at different brightness
levels.
You can verify things if you like. You will need the shop service manual, an
HV probe, DVM, and a scope. You can then follow up on the power supply, high
voltage, horizontal drive pulses, video drive signals to the CRT elements,
focus supply, screen supply, and CRT voltage biases, according to the
references in the service manual.
An experienced TV service tech is used to this type of work. Even though you
are an electronics engineer, TV servicing is specialized work, and
experience as well as a basic knowledge of television equipment is necessary
to be productive in a practical sense.
It would probably be better for you to bring the set to a service centre.
and for the few dollars, they can verify all of this for you.
When working in these TV sets there are also some very serious safety
issues, especially when testing the HV, and working in the CRT bias area.
--
Jerry G.
======
"Prosonman" <prosonman@hotmail.com> wrote in message
news:cu7hf0$bf6$1@sparta.btinternet.com...
Hi All,
I'm an electronics engineer but know very little about T.V repair and was
hoping someone out there may be able to point me in the right direction to
fixing a problem with my T.V.
The problem or problems may be connected, firstly the picture quality has
become quite poor, in that it is no longer a sharp picture but I would say
out of focus particularly on the sides. This is very apparent on writing on
the screen that is virtually illegible and appears to have like a red
ghosting effect on every letter.
The other problem is a brightness problem, it may sound obvious but it gets
brighter when the image on screen has a lot of white in it, even the writing
on screen becomes clearer. For example on a news channel there is a band at
the bottom of the screen giving information, most of the time I find this
hard to read but when the picture above goes to a nice bright outdoor scene
suddenly the writing becomes legible, not perfect but at least I can be read
it.
The T.V is a Sony KV-25K5U that I believe is also called an FE-1, I don't
know if the problem is a faulty tube, a poor HT or bad power supply. Any
help would be greatly appreciated and where to get circuit diagrams would be
helpful.
Many thanks
Richard.
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Andy Cuffe
Guest
|
| Posted:
Mon Feb 07, 2005 11:14 pm Post subject:
Re: Sony KV-25K5U (FE-1) Problem |
|
|
On Mon, 7 Feb 2005 10:55:28 +0000 (UTC), "Prosonman"
<prosonman@hotmail.com> wrote:
| Quote: | Hi All,
I'm an electronics engineer but know very little about T.V repair and was
hoping someone out there may be able to point me in the right direction to
fixing a problem with my T.V.
The problem or problems may be connected, firstly the picture quality has
become quite poor, in that it is no longer a sharp picture but I would say
out of focus particularly on the sides. This is very apparent on writing on
the screen that is virtually illegible and appears to have like a red
ghosting effect on every letter.
The other problem is a brightness problem, it may sound obvious but it gets
brighter when the image on screen has a lot of white in it, even the writing
on screen becomes clearer. For example on a news channel there is a band at
the bottom of the screen giving information, most of the time I find this
hard to read but when the picture above goes to a nice bright outdoor scene
suddenly the writing becomes legible, not perfect but at least I can be read
it.
The T.V is a Sony KV-25K5U that I believe is also called an FE-1, I don't
know if the problem is a faulty tube, a poor HT or bad power supply. Any
help would be greatly appreciated and where to get circuit diagrams would be
helpful.
Many thanks
Richard.
|
It sounds like the CRT is getting weak. I've seen a lot of Sony TVs
with weak CRTs that get sharper and brighter (ususally also tinted one
color) when displaying a mostly white screen. I'm not sure what
causes that odd effect, but I've only seen it on sets with weak CRTs.
You may be able to improve the picture by adjusting the focus control
on the flyback, or CRT neck board.
Andy Cuffe
baltimora@psu.edu <-- Use this email address first
acuffe@gmail.com |
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james
Guest
|
| Posted:
Thu Feb 10, 2005 5:45 am Post subject:
Re: Sony KV-25K5U (FE-1) Problem |
|
|
Sony normally use a 680uf 40- 65 volt elect cap to couple the frame o/p to
the coils, sounds as if it has dried up.
Tom
"Prosonman" <prosonman@hotmail.com> wrote in message
news:cu7hf0$bf6$1@sparta.btinternet.com...
| Quote: | Hi All,
I'm an electronics engineer but know very little about T.V repair and was
hoping someone out there may be able to point me in the right direction to
fixing a problem with my T.V.
The problem or problems may be connected, firstly the picture quality has
become quite poor, in that it is no longer a sharp picture but I would say
out of focus particularly on the sides. This is very apparent on writing
on
the screen that is virtually illegible and appears to have like a red
ghosting effect on every letter.
The other problem is a brightness problem, it may sound obvious but it
gets
brighter when the image on screen has a lot of white in it, even the
writing
on screen becomes clearer. For example on a news channel there is a band
at
the bottom of the screen giving information, most of the time I find this
hard to read but when the picture above goes to a nice bright outdoor
scene
suddenly the writing becomes legible, not perfect but at least I can be
read
it.
The T.V is a Sony KV-25K5U that I believe is also called an FE-1, I don't
know if the problem is a faulty tube, a poor HT or bad power supply. Any
help would be greatly appreciated and where to get circuit diagrams would
be
helpful.
Many thanks
Richard.
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