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Chuck Williams
Chuck Williams, Technician
Category: TV
Satisfied Customers: 3810
Experience:  Over 25 years of experience servicing AV electronics to component level, ISF and THX Cert.
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i have a sony trinitron color tv , model KV32S42. the picture

Resolved Question:

i have a sony trinitron color tv , model KV32S42. the picture continuously flashes on and off on and off. when you first turn it on the little red light in the front of the tv flashes for about 30 seconds before the picture comes on (my instruction book says anything more than 3 to 4 flashes means service is required. once the pictur does come on it continually flashes on and off. is there anything i can do to resolve this problem.
steve Customermsncom
Submitted: 6 years ago.
Category: TV
Expert:  Chuck Williams replied 6 years ago.

Hi, Steve!


I think what you may have is your picture tube is right on the edge of working with the set's AKB, or auto cathode balance. All Sony tube TV's use AKB.


AKB is a circuit that attempts to compensate for aging of the picture tube (among other things), and if the tube isn't conducting enough (due to age), it will intermittently blank the screen or, in sever cases, not allow the picture to come on at all.


But if you are comfortable taking the back off of the set and making a minor adjustment, you can probably restore the picture for a while longer.


Take the back off, turn the set on to a blank channel (receiving snow). You will see a large gizmo with a thick red wire coming out of it going up to the glass on the picture tube. That's the high voltage (a.k.a. flyback) transformer.


On this transformer will be a small knob labeled "Screen." If I'm right, if you turn this control ever-so-slightly counterclockwise, the screen will blank off immediately. But if you turn it just a bit clockwise, it may fix your problem. Don't go too far with this control, just enough to make it work.


Try that, let me know if you have any other questions, and thanks for using JustAnswer!



Customer: replied 6 years ago.

As you point out, I'm not sure I would feel comefortable doing that, but, if I did attempt it. 1. I can remember that the high voltage transformer is the ONE thing you never want to touch, even when the TV is off as you could get seriously shoched. 2. Once the back of the TV is taken off will I be able to turn it on? I thought the end of the plug is attached to the body of the TV to prevent someone like me from getting 'zapped'.

3. You say turn the the knob ever-so- slightly to the right. Can you give an approximate, such as 1/4 turn, 1/2 turn etc. Also, should a counter clockwise turn be made first so the picture does go out as a starting point, or just the slight turn to the right? 4. Will the 'snow screen' also blink, and, stop blinking after turning th knob.



Expert:  Chuck Williams replied 6 years ago.

1. Nonesense. That's a old TV repairman's wive's tale.


2. TV's haven't had rear cover interlocks for decades.


3. Just turn it clockwise until the picture stops blinking on and off. If you turn it too far, the screen will be washed out with diagonal lines, so don't turn it that far.


4. Yes, the snow screen should be all you need.


If you aren't comfortable doing this, I certainly understand. But if you don't want to pay a tech, who may charge you money and say "It's your picture tube, throw it away," then that's your only choice to get it to work. Just remove all the rear panel screws that have a small arrow, and the back shoudl come right off.



Edited by Chuck Williams on 12/21/2009 at 5:55 PM EST
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