Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Sony KV-20XBR Question

I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! Amazing... last week, however, it
decided to die. Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.

Although I'm a tech (RF), I have no experience with TV
troubleshooting. I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. If it's
the latter, cost-effective repair is out the window. I believe this
series of sets had a problem with cold solder joints. Although I
doubt this is the problem, I thought I'd just mention it.

Thanks,
Don
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On Jul 7, 10:11*pm, Don wrote:
I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! *Amazing... last week, however, it
decided to die. *Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. *It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.

Although I'm a tech (RF), I have no experience with TV
troubleshooting. *I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. *Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. *If it's
the latter, cost-effective repair is out the window. *I believe this
series of sets had a problem with cold solder joints. *Although I
doubt this is the problem, I thought I'd just mention it.

Thanks,
Don


Hi Don
I was just going to suggest that. Sony's had A LOT of cold solder
problems. Is it vibration sensitive? Are you certain that it's that
old? If it is the chassis I'm thinking of look at the three pin
regulators especially. The first thing I would do is pull the chassis
and resolder anything that looks suspicious. If the AVboard plugs in
fromthe back and swivels down to remove check the connections on both
boards, especially the mother board. Resoldering fixed a lot of them.
Then try it again. You might get lucky. Let me know. Lenny.
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Default Sony KV-20XBR Question

Don wrote in message
...
I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! Amazing... last week, however, it
decided to die. Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.

Although I'm a tech (RF), I have no experience with TV
troubleshooting. I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. If it's
the latter, cost-effective repair is out the window. I believe this
series of sets had a problem with cold solder joints. Although I
doubt this is the problem, I thought I'd just mention it.

Thanks,
Don



I don't know what is wrong/right/different about my eyesight but I would
consider it torture being placed in front of a pixelated screen rather than
CRT for more than a couple of minutes. Every modern screen I've looked at
(briefly) - anything moving across the image , judders across , in an
intensely annoying manner . So I will will stay with CRT TV for as long as
possible.


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Default Sony KV-20XBR Question

On Jul 8, 3:16*am, "N_Cook" wrote:
Don wrote in message

...





I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! *Amazing... last week, however, it
decided to die. *Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. *It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.


Although I'm a tech (RF), I have no experience with TV
troubleshooting. *I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. *Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. *If it's
the latter, cost-effective repair is out the window. *I believe this
series of sets had a problem with cold solder joints. *Although I
doubt this is the problem, I thought I'd just mention it.


Thanks,
Don


I don't know what is wrong/right/different about my eyesight but I would
consider it torture being placed in front of a pixelated screen rather than
CRT for more than a couple of minutes. Every modern screen I've looked at
(briefly) - anything moving across the image , judders across , in an
intensely annoying manner . So I will will stay with CRT TV for as long as
possible.- Hide quoted text -

- Show quoted text -


There could be a number of causes of the problems mentioned. Lets
start with the "simple" potential fixes:

1) Check the driver transistors on the board that resides on the neck
of the CRT. Check for poor solder connections first. Check the
transistors with a checker for shorts as well. These should be marked
as R, G, B.

2) Check the solder connections at the flyback transformer. These
often crystalize.

3) There should be 2 controls on the flyback transformer itself. One
marked screen and one focus. Try working the screen one back and
forth a bit. I have seen poor contacts inside these cause a dimming
of the picture as well.

Perform the above and report back with the results. I will lok up the
service manual for this model and post any additional common failures
later today.

Dan
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Default Sony KV-20XBR Question

I'm betting on the CRT. This happened to my KV-1920.]

If it's a cold solder joint, a few minutes' work should fix it. If it's a
bad drive circuit (not likely), a 'scope will show whether the signals are
present.




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Default Sony KV-20XBR Question

One other point...

I believe a Trinitron has a single cathode. It's possible the cathode's
emission has fallen to the point where you can't get a picture.


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On Jul 8, 7:40*am, "William Sommerwerck"
wrote:
One other point...

I believe a Trinitron has a single cathode. It's possible the cathode's
emission has fallen to the point where you can't get a picture.


No - separate cathodes. I'm not sure, but I think the "one gun"
description covers it's single focus element. It's possible that he
has a red cathode failure. If the OP has access to a CRT tester,
Trinitrons are checked in the same manner as any color CRT.

OP should reflow the CRT board and flyback, and check solder on all
the TO-220 regulators he can find. After that, it's tracing with a
scope.

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On Jul 7, 9:11*pm, Don wrote:
I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! *Amazing... last week, however, it
decided to die. *Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. *It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.

Although I'm a tech (RF), I have no experience with TV
troubleshooting. *I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. *Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. *If it's
the latter, cost-effective repair is out the window. *I believe this
series of sets had a problem with cold solder joints. *Although I
doubt this is the problem, I thought I'd just mention it.

Thanks,
Don


Do you have an oscilloscope??
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wrote in message
...
On Jul 7, 9:11 pm, Don wrote:
I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! Amazing... last week, however, it
decided to die. Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.

Although I'm a tech (RF), I have no experience with TV
troubleshooting. I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. If it's
the latter, cost-effective repair is out the window. I believe this
series of sets had a problem with cold solder joints. Although I
doubt this is the problem, I thought I'd just mention it.

Thanks,
Don


Do you have an oscilloscope??

and an isolation transformer for it of course


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On Jul 9, 1:57*am, "N_Cook" wrote:
wrote in message

...
On Jul 7, 9:11 pm, Don wrote:



I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! Amazing... last week, however, it
decided to die. Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.


Although I'm a tech (RF), I have no experience with TV
troubleshooting. I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. If it's
the latter, cost-effective repair is out the window. I believe this
series of sets had a problem with cold solder joints. Although I
doubt this is the problem, I thought I'd just mention it.


Thanks,
Don


Do you have an oscilloscope??

and an isolation transformer for it *of course


Yes, I have a scope, and isolation transformer. I do not have a CRT
tester, but I've collected a fair amount of test equipment over the
years. I will attack this problem soon. Thanks.


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On Jul 7, 10:19*pm, klem kedidelhopper
wrote:
On Jul 7, 10:11*pm, Don wrote:



I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! *Amazing... last week, however, it
decided to die. *Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. *It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.


Although I'm a tech (RF), I have no experience with TV
troubleshooting. *I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. *Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. *If it's
the latter, cost-effective repair is out the window. *I believe this
series of sets had a problem with cold solder joints. *Although I
doubt this is the problem, I thought I'd just mention it.


Thanks,
Don


Hi Don
I was just going to suggest that. Sony's had A LOT of cold solder
problems. Is it vibration sensitive? Are you certain that it's that
old? If it is the chassis I'm thinking of look at the three pin
regulators especially. The first thing I would do is pull the chassis
and resolder anything that looks suspicious. If the AVboard plugs in
fromthe back and swivels down to remove check the connections on both
boards, especially the mother board. Resoldering fixed a lot of them.
Then try it again. You might get lucky. Let me know. Lenny.


Yes, it's that old! I purchased it new in April 1986 - hard to
believe it's been that long!
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On Jul 8, 2:16*am, "N_Cook" wrote:
Don wrote in message

...



I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! *Amazing... last week, however, it
decided to die. *Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. *It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.


Although I'm a tech (RF), I have no experience with TV
troubleshooting. *I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. *Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. *If it's
the latter, cost-effective repair is out the window. *I believe this
series of sets had a problem with cold solder joints. *Although I
doubt this is the problem, I thought I'd just mention it.


Thanks,
Don


I don't know what is wrong/right/different about my eyesight but I would
consider it torture being placed in front of a pixelated screen rather than
CRT for more than a couple of minutes. Every modern screen I've looked at
(briefly) - anything moving across the image , judders across , in an
intensely annoying manner . So I will will stay with CRT TV for as long as
possible.


Thanks to everyone for all of the responses. I appreciate it, and
this will help me begin the process. I know what you mean regardless
viewing TV on a CRT vs. a LCD. I agree. That being said, my daughter
recently purchased a Panasonic 32" LED-LCD with a IPS Alpha panel.
It's pretty impressive, and I can actually watch it without getting
eyestrain!
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On Jul 8, 2:16*am, "N_Cook" wrote:
Don wrote in message

...



I have a 25 year old Sony KV-20XBR TV that's been darn near perfect
over a quarter of a century! *Amazing... last week, however, it
decided to die. *Here are the symptoms: 1). Color was obviously off,
so I checked it with a color-dot-bar generator. *It appears the Red is
gone, as the only bars seen are shades of blue and green, and 2).
Later, the picture slowly went to almost black -- you can make out
images, but vaguely.


Although I'm a tech (RF), I have no experience with TV
troubleshooting. *I know the TV is obsolete, but it's in "as new"
condition (not a scratch), and I really hate to take it to the
recyclers. *Any thoughts... do you think it might be in the red drive
circuit, focus circuit, the flyback, or the Trinitron CRT. *If it's
the latter, cost-effective repair is out the window. *I believe this
series of sets had a problem with cold solder joints. *Although I
doubt this is the problem, I thought I'd just mention it.


Thanks,
Don


I don't know what is wrong/right/different about my eyesight but I would
consider it torture being placed in front of a pixelated screen rather than
CRT for more than a couple of minutes. Every modern screen I've looked at
(briefly) - anything moving across the image , judders across , in an
intensely annoying manner . So I will will stay with CRT TV for as long as
possible.


Thanks to everyone for all of the responses. I appreciate it, and
this will help me begin the process. I know what you mean regarding
viewing TV on a CRT vs. a LCD. I agree. That being said, my daughter
recently purchased a Panasonic 32" LED-LCD with a IPS Alpha panel.
It's pretty impressive, and I can actually watch it without getting
eyestrain!
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