Trinitron Foldover

[cato]

I'm pretty sure this problem isn't specific to Sonys...but my Sony is exhibiting it.

The top 25 - 33 percent of the screen has a video haze over it. That is, it appears that the top few scan lines are being relocated from the top of the picture to progressively lower portions of the display. For example, sometimes it will look like the top of someones head is being folded back over their head.

When watching a program off the air, the lowest portion of the phenomenon includes a stripe of color bars. Just above that is a patters of flickering white dots that look to be some sort of digital data, with the left most dots generally fixed and the right most dots doing the bulk of the flickering.

When watching a DVD (letter box) the interference is reduced to a series of white stripes in the general vicinity of the to color bars and white dots discussed above.


Anyone know the cure?

Thanks

73

[dacflyer]

this is common with many tv,,its dried up caps..
in your set, theres a hand full of caps, beside the vertical ic. usually it will be a low value , high voltage cap..usually around 3.3µf or 4.7µf and around 160 volts or so. usually i just replace all the caps around the vertical ic and that cures it 99.99995% of the time , good luck

[cato]

Thanks! any Idea how I might recognize the vertical IC?

[cato]

OK, I pulled the main board out. There is a section silk screened VERT and it includes a shielded section includes a 47uF 35V electrolytic cap, a ceramic cap and a resistor, under the board, tacked on as if an after thought is another 47uF 35V cap and a milar or polyester cap.

Do you think the electrolytics are the ones you are referring to? Should I be looking at the Circuit board that hangs directly to the pins of the CRT?

Thanks

[dacflyer]

nothing will be on the crt board.. most VERT chips now says are mounted on a heat sink..
it might be a LA7838 0r such.. its a chip that has a single row of pins.. and i never seen any under a metal shield
let me know if i can be of further help

[cato]

There was no Chip that I could find. This is a September 1982 Sony KV-1952R we have been discussing by the way.

Anyway, with your input and a few confirming web pages discussing other TVs, I took the bull by the horns and replaced said electrolytics.

I am happy to report that the Fold-over has been cured!

Thank you very much for your replies.

73

[dacflyer]

82 model.. wow.. ok, you might have had the one with descreet transistors in it then,,
( pair of transistors) well i am glad what little info i gave you helped.
glad all worked out for you...
if you ever need a HV tripler for them i have one here. don;t know if its compatable or not,,
sony had a weird way of tv's back then with a dual anode cap that controlled focus and HV
hated them things , that trinitron tube was special made.