lg 50pb2dr-ac plasma

[attainteddragon]

so im finally going to try and learn how to understand these plasmas! be nice!

this unit currently has vertical stripes running up and down the screen and moves slowly across the screen. since i dont know what is displayed, i cant tell which input i am on. still havnt got any sound from the speakers!

the last pic, i managed to bring up something through the menu button.
channel and volume selection slightly changes, distorts my funky lines!

panel states
va 60 i get 59.1 at p 805
vs 192 191.9

any help would be great!

[tom66]

Re: lg 50pb2dr-ac plasma

You'd be looking at the buffer board on this one. A common failure is some FETs on the board -- surface mount devices. Often only the upper or lower fails. You can try running the set with one or the other disconnected.

[attainteddragon]

Re: lg 50pb2dr-ac plasma

thanks tom, ill pull them one at a time to see if i can isolate which board and then test the other to see if is repairable.
ill post results tomorrow, as it is getting a latish here.

[tw2005]

Re: lg 50pb2dr-ac plasma

Like Tom said, most likely shorted buffer board. I've had that with and old 42V6. When it moves across the screen it's probably in TV mode and the small no signal that bobs around the screen would be what it's trying to display.

That's what I worked out with that one and completely disconnecting the lower buffer from the Ysus and the interconnecting cable between the upper and lower gave me a perfect top half with that set.

[attainteddragon]

Re: lg 50pb2dr-ac plasma

hey tw.

i pulled out the lower buffer board and now have a great looking top half.

the fets have tested bad, i'll pull them out of circuit tomorrow and check the smd's!

there is no visual defects with the buffer chips but ill check them over too!

[tw2005]

Re: lg 50pb2dr-ac plasma

I've never tried a buffer repair on them so that's my limited experience. Last LG I touched was a PX5D, Those IPMs turned me off LG for good.

[attainteddragon]

Re: lg 50pb2dr-ac plasma

i received my mosfets today (fqb46n15) and swapped out the bad one.
all up and running, on test now.
thanks guys.
now, do i sell my kdl-46x3100 or this one!
this one is a bit bigger and has a twin tuner and hard 250 gig hard drive!
decisions, decisions! :/

[tom66]

Re: lg 50pb2dr-ac plasma

I would keep the 46" Sony; this set isn't as good as it, except on motion performance.

[attainteddragon]

Re: lg 50pb2dr-ac plasma

cool, ill probably keep the sony. well, till i fix a better one that is.
at least i know i will make a few dollars on this one. free tv and $1.65 mosfet!
i like it when i have a win!

[retoware]

Re: lg 50pb2dr-ac plasma

First, thanks for all of the helpful posts. I have a LG 50PC3D that was having the same problems as the original poster. The FETs on the lower Y buffer were shorted. After replacing that board with a refurbished part, the set worked fine for 45 minutes at which time is started exhibiting the same problem as before. Suspecting a heat problem, I turned the set off and then back on at which point I heard a loud snap/pop. Now, there is a dead short between Vs and GND on the Y sus board - even though all of the fuses on the Y sus board are intact. Visually, the buffer boards seem ok and the FETs are not shorted.

My question is whether I should replace the Y sus board and/or the buffers? Is there something else (possibly the panel) that could have caused the Y sus board to short out in this manner? The set is 8 years old and I'm loathe to replace the Y sus and buffers only to have them blow again.