Please Help! Tortuous Television Trouble

[DrewK]

I have a Tobisha TV. It is 32 inches. I do not know when it was made
but I would have to say late 90's, maybe 98-99. It is your standard
old TV, not one of the new fancy ones that everyone is buying.

Here is the problem.....


The image on the television constantly contracts. The sound is
perfect. When you turn the TV on the picture is fine. After a
certain amount of time, which is variable and (seemingly) random, the
picture slowly condenses to the center of the screen. It would seem
like someone is squeezing the picture from the top and the bottom
simultaneously. The picture squuezes into a rectangular box in the
center of the screen, about 6 inches on the side, while the rest of
the tv remains black. There is no squeezing from the left or the
right. Sometimes this picture will flutter between 3 inches wide to
maybe 9 inches wide on the side. Sometimes while in this state the
picture will spontaneously jump back to the full size and stay there
for a couple of minutes, only to return inevitably to the condensed
version.


Upon smacking the top of the TV with my fist the picture returns to
the full screen every time. If i only lightly smack it it will grow
larger on the top and the bottom. So smacking fixes the problem
temporarily.


I would appreciate any and all input anybody has on this matter. I am
determined to get to the bottom of the issue and would not mind
attempting to fix the problem on my own. Please let me know if anyone
can diagnose the problem and reccommend a possible solution.


Thank you very much,


Best Regards,


Andrew Kotheimer


TO CLARIFY: The picture at no time shrinks or condenses from the left or right sides of the screen, only from the top and bottom. I apologize if this point had confused anybody.

[gary]

sounds like dry joints on the frame ic or in the frame stage, resoldering the ic will probably cure your problem, cant be anymore more specific as you didnt give any indication as to model or chassis.

[cory]

resolder vertical ic.on heat sinc,probably 7 pins.starting with la....,maybe.

[Guest]

I have been doing some research at the library regarding the problem I have with the TV. I do not have a manual for this TV and have not been able to locate one, and more so I am a complete novice, but with plenty of ambition.

Now, please forgive me if my questions sound stupid, but this is only because of the fact that I know almost next to nothing about any of this.

Does the vertical IC appear on the 'motherboard' as a small, black rectangle? and if this is true, are the pins the little silver things coming out of the side? (please excuse my butchering of the terminology), this is what some of the pictures have suggested to me.

Also, I assume that I am dealing only with the vertical output circuits?
And are both the input and output signals on the same vertical IC (i.e. is it an all-in-one type of package?)

What is a heat sink and how would i identify it?

Would a manual, with a layout of the specific circuitry be nessecary for the resoldering of the verticle IC?

Do each of the 'pins' on the verticle IC have a different function, and if so, how do I identify the problem pin from all the others (manual?)

If you had to catagorize this problem specifically, what would you call it? Would you call the problem "convergence"??

Thank you in advance for all your help thus far, I really do appreciate it. Also if you could answer these questions you would all be of the greatest help as I am trying to learn as much about this as possible. Please in any answer you give do not hold back any technical terminology, I have taken some physics and am vaguely familiar with some of this (ohms, watts etc..) the more technical and precise the better.

thank you again and i hope to hear from you all soon.

-

[gary]

POST THE MODEL NUMBER AND SOMEBODY MAY BE ABLE TO TELL YOU THE CIRCUIT REFERENCE OF THE ITEM THAT REQUIRES SOLDERING, WOULD MAKE IT QUICK AND EASY

[DrewK]

I have the chassis number as: TAC9516

the model number is CF32E50

it is a toshiba and was manufactured April of 1996

[fRANK]

Could be the ,SCAN COILS