panasonic TH-42PC77U plasma television half screen problem

[renech]

hello,
I hope someone on this forum can assist me.
I have a panasonic TH-42PC77U plasma television.
the lower 1/2 of the screen has become flaky....in and out, then finally goes black and you can only see the top portion.
i have performed the reset to default settings quite a few times. Panasonic recommended..did not believe this would help...it didn't.
I have removed the back panel and looked around for something obvious...burn marks in a board, etc....nothing obvious...
I have read some posts that suggest the problem is related to the boards on the left side of the TV.
possibly the lower board which is a TNPA4185.
is there a way to isolate the problem further to ensure it relates to this board or something else?
I do have an electrical test meter and would appreciate some instruction if tests are suggested.
any assistance would be appreciated....
thank you!!
Rene

[nomoresonys]

Re: panasonic TH-42PC77U plasma television half screen problem

find the ground on that lower Y-buffer board and test for shorts, one example there: https://www.youtube.com/watch?v=V6hxf9sARMY

[renech]

Re: panasonic TH-42PC77U plasma television half screen problem

ok nomoresonys...thank you very much for the response!!
i will try that...may not get to it today...
rene

[Davi.p]

Re: panasonic TH-42PC77U plasma television half screen problem

Maybe a power feeding connection problem with the lower ybuffer board?

[renech]

Re: panasonic TH-42PC77U plasma television half screen problem

Hello!
I removed the lower board...it is a little different than the one in the video. I am not sure how to add a picture to the post...
I have an analog multimeter...had an inexpensive digital one..not sure where it is...i set the meter to continuity. when i attach to certain pins on the main connector to the power control the board? and run the alternate wire across the 4 different IC's, it registers 1/2 continuity or beeps.
I did notice that 2 of the 6 IC's don't seem to have the panasonic writing on them...not sure if that means they burned out??
my apologies for my electrical knowledge, but I'm interested in learning from some masters.
what would you suggest next?
can i post a picture some how?
thank you!

[R_J]

Re: panasonic TH-42PC77U plasma television half screen problem

To attach a picture, Go Advanced, then click on the paper clip (next to the ) I don't remember exactly, with the board removed and with your meter in diode test, place one probe on a set of pins that connect to the Y-sus board and with the other probe test each pin on the brown plug that would connect to the panel ribbon cable, you should get a reading of .7xx check each pin and if one or more is shorted, that is the ic that is bad.

[nomoresonys]

Re: panasonic TH-42PC77U plasma television half screen problem

so you are getting 1 or 2 beeps and the rest are not beeping that equals a shorted board, need a new board or 1 or more IC's replaced, simple as that, I would also test the upper.

[nomoresonys]

Re: panasonic TH-42PC77U plasma television half screen problem

If you do get a replacement, make SURE you test it before installing it, so you are sure it is not shorted, because there are many people selling them that are clueless as to how they work, those ic chips short out and show no outward signs at all, sometimes they do but it's not a rule and installing a bad one can mess up a good Y-SUS and vice versa. If I ever have cause to buy another which I doubt I will, I would ask the seller to test it, if they can't I would move to a seller that will.

[renech]

Re: panasonic TH-42PC77U plasma television half screen problem

Hello R_J...yep....the picture you attached is the same board. thank you for the attachment instructions by the way....
as far as the pins that attach to the Y-SUS board..there are many and they seem to go to different parts of the board....can you tell me which pin or pins do I need to use?
thank you

hello nomoresonys....I need to try the test again...thank you for the feedback also..
renech

[R_J]

Re: panasonic TH-42PC77U plasma television half screen problem

I don't remember which pins to put the probe on, there are only 5 sets of pins, try with your probe on one of the sets of pins, then with the other probe check the brown plug pins, they won't all be shorted so you should see a reading of .6xx on your meter, when you figure out which combination gives you that reading, then leave the probe on the pins (SC board plug) and probe all the pins on the panel (brown) plug

In Panasonic plasma's the Y-sus board is the SC board

[renech]

Re: panasonic TH-42PC77U plasma television half screen problem

Hello
I have tested the lower board.
I get a reading of .6 or .7 on the analog multi meter.
I have not tested the upper board.
I figured if the problem is the lower part of the screen, would be associated with the lower board?
What would you suggest to do next?
Upper board or something else?
Thank you!
Renech

[R_J]

Re: panasonic TH-42PC77U plasma television half screen problem

Did you check each pin and both sides of the connector that goes to the panel?

[renech]

Re: panasonic TH-42PC77U plasma television half screen problem

Hello r_j
I attached a picture.
Hopefully i am testing correctly?
I held the right probe stationary and moved the left probe down all brown connectors.
I got a reading of. 7
One other note.
You can't read the word panasonic in the top two ICs like you can on the rest.
Does that matter?
Renech