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Louie, Technician
Category: TV
Satisfied Customers: 2557
Experience:  25+ yrs. experience in the field and 5+ yrs. online, down to component level.
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Panasonic TH-58PZ700U is showing intermittent black

Customer Question

Panasonic TH-58PZ700U is showing intermittent black horizontal lines or noise over middle 1/3 of screen. Somewhat dependent on what is on the screen. These are not bars but short failures during the scan across the screen. Have read about reseating the connectors to the SC SU SD boards or replacing to test. What board is responsible for that 1/3 of the screen?
Submitted: 1 year ago.
Category: TV
Expert:  Steve G. replied 1 year ago.

Hello there and welcome to Just Answer. My name is ***** ***** I will be assisting you today. I am an engineer with over 30 years of electrical and electronic training, repair and installation experience. I will try and answer your question accurately and precisely so that we can get you on your way.

I do not have good news: this is most likely the failure of a sustain buffer board but it could be other things. A repair will require taking the set apart and swapping out one or more boards. Is that something you could do yourself? If the TV is out of warranty, it will probably be a repair in the $300 range, maybe more depending on the availability of parts.

I can help you troubleshoot or I can find you a tech in your area.

How would you like to proceed.

Customer: replied 1 year ago.
I have no problem replacing the boards and have replaced another board HDMI previously. So it is good news not bad.
So how do we localize the failure?
Expert:  Steve G. replied 1 year ago.

Ok, that's excellent. Let me grab the manual off my work server and we can start. Hold on please.

Customer: replied 1 year ago.
Great. More info/question. The TV is mounted very precariously and not easy to open and look at the board #s for now. How safe are we ordering a replacement sustain board and making the assumption that the replacement board is a variant for that model and incompatible?
Expert:  Steve G. replied 1 year ago.

Ok, now you say that the problem is in the middle 1/3rd of the screen. If you divide the screen in half - upper and lower, are the 'lines' in the upper, lower or both?

Secondly, it sounds like these 'lines' do not completely traverse the screen from left to right. Is that the case?

Please let me know so that we can continue.



Customer: replied 1 year ago.
The lines are exactly in the middle 1/3 - nothing at all is wrong on the upper 1/3 or lower 1/3.
ALSO to be clear they are not lines but short random segments with many across a single scan line. They are not solid lines across the whole face of the screen.
Expert:  Steve G. replied 1 year ago.

Ok, hold on please. I'm wondering if the 58" has three buffer boards. Let me check.

Customer: replied 1 year ago.
I grabbed a partial screen shot that shows the lines well....
Expert:  Steve G. replied 1 year ago.

Ok, got that. Please hold for a second, I'm pulling some documentation from my office server.

Expert:  Steve G. replied 1 year ago.

Nope, this set has an upper (SU) and lower (SD) buffer so let's be clear about these lines. The photo you sent makes it appear that the lines are over a considerable portion of the screen, not the 'middle third'. Can we say that the lines appear in the top half and the bottom half of teh screen simultaneously?

Customer: replied 1 year ago.
My initial picture didn't show the full screen - I was focusing in on the line segments. This picture does a better job of showing where the lines are. I crudely measured and it is exactly 1/3 in the middle. I agree strange given only 2 boards SU SL. I do notice that there are 4 connectors on each - maybe both boards have failed and the lower half of one and the upper half of the other.
Customer: replied 1 year ago.
Rotate the picture - the lines are actually horizontal...
Expert:  Steve G. replied 1 year ago.

I see the horizontal lines.

I assume this happens on all inputs and and iin the TV's own menus also. If so, then we need to look at SC, SU, SD and SS. It could under some circumstances be the D board and it could very well be your actual panel.

Hold on please.

Customer: replied 1 year ago.
definitely on all inputs and I just rechecked it shows up over the menus also.
That sounds like it could be an expensive swap-fest... no clear culprit.
Expert:  Steve G. replied 1 year ago.

I would remove the SU SD and SC boards and then put them back again. The three are interconnected so this might fix a troublesome connection between them. Also remove and replace back the SS board.

Once you have done that, if the lines are still there, see if the lines have 'moved' location.

Customer: replied 1 year ago.
Yea - that sounds like the best approach.
Unfortunately I can't do this now - so this will have to go on hold for a day or so.
I assume clean the contacts with isopropyl alcohol and blow out all the dust inside?
If I come back to this tomorrow will you still be the responder?
Expert:  Steve G. replied 1 year ago.

Yes that sounds like the correct approach. And I will be here tomorrow.

Until then.