Entertainment Center: TVs, Stereos, VCRs and DVDs - 27" panasonic

Hi,

Our 8 Year old 27" Panasonic displays thin white horizontal lines about two inches from the top of the picture tube. Within the lines is a ghost image of what is on the rest of the screen. Once the tv is on for about 10 minutes the lines go away. Any ideas?

Thanks!

It's called vertical foldover. If you can use a soldering iron, we have a kit that will fix it. Toshiba kit #2.

Dakota
http://www.fixyourowntv.com

Here's a snippet (below) from the TV repair FAQ in sci.electronics.repair. http://www.repairfaq.org/sam/tvfaq.htm

I think this is useful information to help you decide what's going on.

BTW, Dakota can sell you the bag of IC's to fix this. If you'd like, I can sell you a bag of caps to solve this problem lickety-split, but I'll include a heavy duty 500W soldering iron with some spare tips in case you burn one out while soldering some parts. Its catalog number is FixItAll Kit #1. LOL!! ;-) [sorry... my gut is busting up from laughing! LOL LOL LOL!]



Vertical foldover
The picture is squashed vertically and a part of it may be flipped over and distorted.

This usually indicates a fault in the vertical output circuit. If it uses an IC for this, then the chip could be bad. It could also be a bad capacitor or other component in this circuit. It is probably caused by a fault in the flyback portion of the vertical deflection circuit - a charge pump that generates a high voltage spike to return the beam to the top of the screen.

Test components in the vertical output stage or substitute for good ones.
Comments on vertical problems
(From: Bert Christensen (bert.christensen@rose.com).)

As a general rule, vertical faults can be divided into two types: ones that cause geometric distortion (a circle will not be round) and those that simply black out a portion of the screen. The former are faults in the vertical oscillator, drive, or output stages. The latter are blanking faults. Blanking faults are almost always caused by electrolytic capacitors changing value and thereby changing the timing of the pulses which blank the screen during vertical retrace. In other words, the pulses are turning off the video signals at the wrong time.

The most common true vertical fault is geometric distortion and a foldover of white lines at the top of the screen. This is almost always caused by the electrolytic capacitor on or near the collector of the vertical output transistor or part of the IC which has the supply voltage (B+) on it. In the old tube days, the general rule was that bottom distortion was in the cathode of the output tube and distortion at the top was caused by a fault in the drive circuit.

Perhaps alung would like to share with us which parts are defective, there location, there value?

Dakota

Nope, sorry, I can't tell you what there [sic] location or what there [sic] values are.

I can't rely on my Magic 8 Ball to answer these types of questions. I guess I need a bigger and newer one since the original poster never mentioned what model number TV he has, nor would I ever have a chance to physically look inside his TV to confirm whether those parts are indeed bad!

Would you insist on having a root canal done only because someone who has never seen your teeth say you needed one?

To alung

I dont think people here are looking for a magic 8 ball. I think they are looking for real answers.

And yes I think a dentist can make an informed desicion based on a description and years of experience.

By the way what TV repair experience do you have?

Dakota
28 years and counting!

for suggesting that it's vertical foldover. (by the way, the TV is closer to 10yrs old as it is the model just prior to the gaoo).

-called a repair shop today...was able to speak intelligently with a service rep and the result is: free pick up and delivery and assurance that worst case scenario for the fix will be no more than $200. (i'm sure the "free" p&d is included in this cost).

What was nice to hear on the other end of the phone is that this is a good set, easy to work on, that there's a fairly high level of isolation between components (ie, if something blows, it tends not to take 5 other things with it...so the repair shop says.)

Thanks for the input.

by the way, I would NEVER fart around with the guts of a TV - shaky hands and lack of patience.

J

bad vertical circuit. $200 including diagnosis, pick up and delivery.