TV Image Not Filling Up Screen

[vilja]

I have a Philips 9P5511 large screen TV that shows an image smaller
than the screen. It first stared with a jittery image. Now when I
turn it on the image is shaped like a sofa cushion (rounded sides but
corners still visible). If I leave it on for a few minutes the image
stretches to fill the screen vertically but it is still jittery.
Someone told me the Vertical Deflection IC was bad so I changed
it--wrong. What else could it be? I've examined the circuit boards
for signs of damage but everything looks good.

 

[Leonard Caillouet]

I have a Philips 9P5511 large screen TV that shows an image smaller
than the screen. It first stared with a jittery image. Now when I
turn it on the image is shaped like a sofa cushion (rounded sides but
corners still visible). If I leave it on for a few minutes the image
stretches to fill the screen vertically but it is still jittery.
Someone told me the Vertical Deflection IC was bad so I changed
it--wrong. What else could it be? I've examined the circuit boards
for signs of damage but everything looks good.

Someone told you wrong. You likely have the common optocoupler problem in
the power supply.

Leonard

 

[vilja]

Which optocoupler? Is there more than one?

 

[b]

I have a Philips 9P5511 large screen TV that shows an image smaller
than the screen. It first stared with a jittery image. Now when I
turn it on the image is shaped like a sofa cushion (rounded sides but
corners still visible). If I leave it on for a few minutes the image
stretches to fill the screen vertically but it is still jittery.
Someone told me the Vertical Deflection IC was bad so I changed
it--wrong. What else could it be? I've examined the circuit boards
for signs of damage but everything looks good.

mains filer cap bad? seems like inadequete voltage on the b+.

 

[vilja]

Ok, but how do I know which filter cap?

 

[vilja]

I noticed something else: once the image fills the screen the B+
voltage is at 130 V but when I change channels it drops to about 110
V. What could that mean?

 

[b]

vilja ha escrito:

Ok, but how do I know which filter cap?

read it again, the *mains* filter cap.
judging by your responses I gather you are out of your depth here. For
your own safety I'd recommend having a tech look at this. You could
get injured, killed or mess things up beyond economical repair if you
go tinkering and guessing.

-B..

 

[Franc Zabkar]

I noticed something else: once the image fills the screen the B+
voltage is at 130 V but when I change channels it drops to about 110
V. What could that mean?

It's probably not the changing of channels that causes your B+ to
vary, it's most likely the change in image brightness, which in turn
results in a variation in the beam current. A higher beam current
means that the B+ droops under the extra load. I've seen these kinds
of faults caused by a bad filter cap on the B+ line, probably a 160V
type. I'd also check the mains filter cap as already suggested.

- Franc Zabkar

 

[vilja]

Thanks for the advice. I'll start with the caps on the B+ line then
move to the mains. My multimeter doesn't have a capacitance setting.
Is there some way I can check the caps with a scope or a regular
multimeter?

 

[Leonard Caillouet]

The location number in the sets that have this problem is 7412, IIRC.

Leonard

 

[vilja]

Thanks, Leonard. I was probing the pins on this device earlier and
something strange happened. When I touched my multimeter to pin 7 the
TV made a noise like it was about to shutdown. As if the circuit was
somehow being overdriven. I noticed that pin 7 is the base voltage
and on my circuit is connected to ground through a 500k resistor. I
thought it odd since pin 5 is also connected to ground through a
resistor and nothing happened when I checked the voltage there. Could
it be that my multimeter was doing something screwy or is it a sure
sign that this is the bad part?

 

[Franc Zabkar]

Thanks for the advice. I'll start with the caps on the B+ line then
move to the mains. My multimeter doesn't have a capacitance setting.
Is there some way I can check the caps with a scope or a regular
multimeter?

If your cap is bad, I believe you should see a lot of high frequency
ripple on your scope. I generally use an ESR meter. In any case a
replacement cap is cheap so I would change it just for good measure.

- Franc Zabkar

 

[vilja]

Changed the cap and still not good. I'll try to the opto coupler
next.
Thanks.

 

[vilja]

It worked!!!! I changed the optocoupler and it's working now. I
never would have guessed it. Thanks for everyone's help. It's great
to have my TV back

 

[bass0r]

Can someone show me which part to buy and replace?

Thanks

Bas

 

[AZ Nomad]

Can someone show me which part to buy and replace?

you're joking, right? Turn the TV around, look up the model number and order
one of those. Then call an installer. You're too stupid to handle connecting
the power cord and the signal cable(s).

 

[bass0r]

Now thats really nice, your surely not very smart! How can you justif
an atitude like that?

Now if you weren't hiding behind your anonymous on-line persona, an
had the guts to speak to me in person like that I am pretty sure yo
would either choose not to be rude or would walk away with a hurt jaw.

So now back to the helpful information.

I know WHERE the part is I know WHAT the part is.

What I meant to say/ask is where can I FIND this part on the interne
or cross it with a like part from NTE or somewhere else

 

[AZ Nomad]

Now thats really nice, your surely not very smart! How can you justify
an atitude like that?

Now if you weren't hiding behind your anonymous on-line persona, and
had the guts to speak to me in person like that I am pretty sure you
would either choose not to be rude or would walk away with a hurt jaw.

So now back to the helpful information.

I know WHERE the part is I know WHAT the part is.

Stupid ****. You haven't even posted what make and model tv it is.
And where did you get the *insane* notion that it is a universal part
responsible for "filling up" the screen? So far all you've narrowed
it down is to about fifty million possible parts.

 

[Homer J Simpson]

Now thats really nice, your surely not very smart! How can you justify
an atitude like that?

Now if you weren't hiding behind your anonymous on-line persona, and
had the guts to speak to me in person like that I am pretty sure you
would either choose not to be rude or would walk away with a hurt jaw.

So now back to the helpful information.

I know WHERE the part is I know WHAT the part is.

What I meant to say/ask is where can I FIND this part on the internet
or cross it with a like part from NTE or somewhere else.

Just use a 12AX7 or ECC83

 

[Meat Plow]

Can someone show me which part to buy and replace?

Thanks

Bass

Part for what?