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.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1
Default sony kv32xbr55 - Left side of screen is totally green until warmed up, then OK

I have a sony kv32xbr55, around 13 years old that still has a good
picture when working. It suddenly developed a problem that occurs
when first turned on. The left 1/4 of the screen is green from top to
bottom. It is a band that has strait edges on the left and right. It
usually clears up after about 30 minutes. Before clearing up, the
green band starts breaking up with horizontal lines all across the
screen. After clearing up it works OK for hours, until turned off.

Can anyone offer a clue about what might be causing this? I got an
estimate of $250 to repair but I would rather put that on a new
flat-panel LCD. I am an experienced electronics technician and handy
with an oscilloscope but I am hoping someone might have experienced
this problem and save me a lot of time.

Thanks for any help.
G.M. Durrence
(to reply remove -nospam from address)
  #2   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 259
Default sony kv32xbr55 - Left side of screen is totally green until warmed up, then OK

Most likely defective caps in the horizontal scan area, or in the blanking
circuits. If you use an ESR meter on all the caps, you will probably find
the defective one. Considering the age of the set, you will most likely find
many caps that are high in their ESR spec. You may end up changing a dozen
or more caps if you go through the complete set.

Most of these thermo type problems are from caps starting to go defective.

To troubleshoot the set with a scope and meter, you will need the service
manuals to be able to determine where you are going, and what you are
looking for. This method would also be very time consuming.

Personaly, with a set that old, I would be out shopping for a new LCD type.

--

JANA
_____


"G.M. Durrence" wrote in message
...
I have a sony kv32xbr55, around 13 years old that still has a good
picture when working. It suddenly developed a problem that occurs
when first turned on. The left 1/4 of the screen is green from top to
bottom. It is a band that has strait edges on the left and right. It
usually clears up after about 30 minutes. Before clearing up, the
green band starts breaking up with horizontal lines all across the
screen. After clearing up it works OK for hours, until turned off.

Can anyone offer a clue about what might be causing this? I got an
estimate of $250 to repair but I would rather put that on a new
flat-panel LCD. I am an experienced electronics technician and handy
with an oscilloscope but I am hoping someone might have experienced
this problem and save me a lot of time.

Thanks for any help.
G.M. Durrence
(to reply remove -nospam from address)


  #3   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,572
Default sony kv32xbr55 - Left side of screen is totally green untilwarmed up, then OK



Meaning they need to warm up before the problem went away? I can't
remember when I've seen a weak cap work better when it was warm (not
saying it doesn't happen). Lots of times I've lucked out with some freeze
spray reviving caps. Guess the OP could wait until the set warmed up and
the pic was ok then use a little freeze rather than removing dozens of
caps and esr'n all of them.


That's how it always is with electrolytics, the ESR drops as the
temperature rises. You can try it with any marginal 'lytic and an ESR
meter, shoot the cap with freeze spray and the impedance will skyrocket.
Heat it with a hair dryer and it will drop.

Rule of thumb is that if something works better as it heats up, look at
the caps. If it works better cold, look at the semiconductors. If it's
erratic, look at solder joints.
  #4   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 221
Default sony kv32xbr55 - Left side of screen is totally green until warmed up, then OK

On Sat, 06 Jan 2007 11:53:31 -0500, G.M. Durrence
wrote:

I have a sony kv32xbr55, around 13 years old that still has a good
picture when working. It suddenly developed a problem that occurs
when first turned on. The left 1/4 of the screen is green from top to
bottom. It is a band that has strait edges on the left and right. It
usually clears up after about 30 minutes. Before clearing up, the
green band starts breaking up with horizontal lines all across the
screen. After clearing up it works OK for hours, until turned off.

Can anyone offer a clue about what might be causing this? I got an
estimate of $250 to repair but I would rather put that on a new
flat-panel LCD. I am an experienced electronics technician and handy
with an oscilloscope but I am hoping someone might have experienced
this problem and save me a lot of time.

Thanks for any help.
G.M. Durrence
(to reply remove -nospam from address)


If it gradually fades back to normal from left to right, then the most
likely cause is a bad capacitor near the flyback. It will probably be
a high voltage one (160v-300v). When electrolytics start to fail,
they get better as they warm up.
Andy Cuffe


  #5   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 177
Default sony kv32xbr55 - Left side of screen is totally green until warmed up, then OK


James Sweet wrote:

Meaning they need to warm up before the problem went away? I can't
remember when I've seen a weak cap work better when it was warm (not
saying it doesn't happen). Lots of times I've lucked out with some freeze
spray reviving caps. Guess the OP could wait until the set warmed up and
the pic was ok then use a little freeze rather than removing dozens of
caps and esr'n all of them.


That's how it always is with electrolytics, the ESR drops as the
temperature rises. You can try it with any marginal 'lytic and an ESR
meter, shoot the cap with freeze spray and the impedance will skyrocket.
Heat it with a hair dryer and it will drop.

Rule of thumb is that if something works better as it heats up, look at
the caps. If it works better cold, look at the semiconductors. If it's
erratic, look at solder joints.


If the set will work ok when warmed up with the back off, I would let
it warm up, run ok for a few minutes, and then apply cooling to all the
caps to see if one or more respond with a bad picture. If not, then go
after cooling the other components. Alternatively, you could apply
heat to components when the set is first turned on and see if you can
speed up the process toward getting a good picture. Method 1 is
preferable.

H. R. (Bob) Hofmannn

Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sony KV-X2933E 29" tv, sound gone left side Mogens V. Electronics Repair 1 March 26th 06 07:23 PM
Acer 77e Black Screen Until Warmed-up John Keiser Electronics Repair 4 November 7th 04 04:26 PM
Samsung TVp5050f chassis scv11A left side of screen blank ! AKDIFFUSION Electronics Repair 0 August 27th 04 03:35 PM
New GE 32GT740 32" TV...Faint Vertical Bars on Left Side Of Screen Q.E.D. Electronics Repair 3 August 14th 03 06:35 PM


All times are GMT +1. The time now is 01:27 AM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"