Sanyo DP50749 Plasma No picture

[1997eclipsegst]

Hi everyone,

I am working on a Sanyo DP50749 Plasma. This tv has LG internals. When I first tried to power it on it didn't have a picture but had sound. After checking the upper and lower buffers, Y-SUS, Z-SUS. I found the lower buffer had a shorted IC. I found a couple of replacements but are quite a bit more expensive then the Samsung buffers I have purchased recently. So I wanted to see if I could get the tv to fire up before buying a replacement. After removing the shorted IC from the buffer the tv will turn on but the lower half of the screen is dark. I realize the area where the buffer was removed would be black, but would all the other areas not work as well? The other problem I see with this tv is a black vertical bar. I have tried to reseat the connector to the lower buffer with no luck. I am guessing this a has a bad panel as well. Any thoughts?

[tom66]

Re: Sanyo DP50749 Plasma No picture

Yes, the panel appears bad on this model.
When you remove an IC the signal which is chained from the top IC downwards will go missing so it's natural to see no picture from that IC onwards.

[1997eclipsegst]

Re: Sanyo DP50749 Plasma No picture

That's what I was afraid of. Thanks for the info on the IC. That makes sense now since the one removed was closest to the middle of the tv with three below it.

[tom66]

Re: Sanyo DP50749 Plasma No picture

Out of interest, do the lines below that IC have any priming glow (visible light in a dark room?) Or is it just the ones above it?

[1997eclipsegst]

Re: Sanyo DP50749 Plasma No picture

The lines in conjunction with the IC removed did not have any priming glow but the 3 below did prime just no picture.

[tom66]

Re: Sanyo DP50749 Plasma No picture

Interesting. It confirms my theory that they are relying on the secondary breakdown of the IC to prime the panel.

[Redrock2002]

Re: Sanyo DP50749 Plasma No picture

I know this is an old thread, sorry, but I am unable to post my own thread. I have a Sanyo dp50747-02 tv that had bad caps on the power supply. I replaced those and am now able to power on the unit but there is 2 vertical black bars displayed. One is all the way on the left side and the other is all the way to the right side. I found a service manual and was able to induce the panel test and the test DID display in the two areas described above. Does that mean I need to replace the two bottom buffer boards? THanks in advance!!

[tw2005]

Re: Sanyo DP50749 Plasma No picture

I know this is an old thread, sorry, but I am unable to post my own thread. I have a Sanyo dp50747-02 tv that had bad caps on the power supply. I replaced those and am now able to power on the unit but there is 2 vertical black bars displayed. One is all the way on the left side and the other is all the way to the right side. I found a service manual and was able to induce the panel test and the test DID display in the two areas described above. Does that mean I need to replace the two bottom buffer boards? THanks in advance!!

If a test pattern gave you normal/full screen then panel and logic board are good. That leaves the mainboard as the issue or display ratio is set wrong or program could be in a letterbox format.

[Redrock2002]

Re: Sanyo DP50749 Plasma No picture

Well, after I reconnected the LVDS and the 3 connectors on the PSB that I removed to conduct the panel test, I turned it back on to test your theory on ratio and low and behold it's showing full screen. No vertical black bars. So either loose connection or from me moving the tv on my own probably slightly flexing the unit fixed it. I'll chalk it up to my magic touch.

[Jumpa]

Re: Sanyo DP50749 Plasma No picture

I have this same TV "Sanyo DP50749 Plasma" however the left side about 15" in is all black yet the other 3/4 of the screen is fine.
It does this when it is hooked up to a cable box or not

One thing to note is I was taking the stand off and it got hung up on the inside the right side metal stand fell out and the left side got hung up on an angle. I was holding it by myself so I gently wiggled the TV it until it fell out.

Not sure if this caused the issue.
Also sometimes if I turn it on / off while it is warm I will get multi colored vertical rainbow lines from the top to the bottom of the TV the black screen or rainbow vertical lines are all only about 15" in from the left hand side facing the screen the rest of the screen is normal
Please help!! if you can Much appreciated either way !! l

[Jumpa]

Re: Sanyo DP50749 Plasma No picture

If I pinched the ribbon "pic 2" would that cause my issue here?...I have since taken the ribbon out and there are a couple tiny tiny holes where I can see copper or brass like metal ... it appears to have been pinched , might this cause the symptoms i described above?

[Jumpa]

Re: Sanyo DP50749 Plasma No picture

https://www.badcaps.net/forum/attach...4&d=1446745569

[Jumpa]

Re: Sanyo DP50749 Plasma No picture

Anyone?

[freakaftr8]

Re: Sanyo DP50749 Plasma No picture

Yes if that ribbon cable is damaged it all you will have a area in the picture that will have vertical multicolored lines or no picture at all is that looks like it carries the information for the vertical drivers on the panel.

That's most likely your problem. Now I believe that panel is manufactured by Panasonic if I'm not mistaken.

[aaronwt6]

Re: Sanyo DP50749 Plasma No picture

Absolutely. And I wouldn't recommend powering the TV up again until that ribbon is replaced. You would be risking further damage to the TV from a short.

[aaronwt6]

Re: Sanyo DP50749 Plasma No picture

Yes if that ribbon cable is damaged it all you will have a area in the picture that will have vertical multicolored lines or no picture at all is that looks like it carries the information for the vertical drivers on the panel.

That's most likely your problem. Now I believe that panel is manufactured by Panasonic if I'm not mistaken.

Beat me to it. And yes, that's definitely Panasonic parts other than the Sanyo Main Board.

[freakaftr8]

Re: Sanyo DP50749 Plasma No picture

Agreed. The chip on film technology incorporated into plasmas for the vertical gate drivers are very finicky and you could easily short them out

[freakaftr8]

Re: Sanyo DP50749 Plasma No picture

Haha winner winner chicken dinner lol

[freakaftr8]

Re: Sanyo DP50749 Plasma No picture

It's going to be hard to find that ribbon. Measure width and length and how many nodes on the ribbon I may have one in my stash.

[Jumpa]

Re: Sanyo DP50749 Plasma No picture

It's going to be hard to find that ribbon. Measure width and length and how many nodes on the ribbon I may have one in my stash.

Awesome bro will do that right now!