Electronics > Repair

LCD TV with extreme ghosting

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PA0PBZ:
I have here a Philips 37PFL5603D/10 from my daughter that keeps me puzzled.
At her house the picture went very dark after 10 minutes from switching it on, so I took it home to check the backlights and the inverter. Of course at my house it did not turn dark, even after a few hours, not even when I put the back on it again, thought it might be heat related, but no. What I did notice is that the overall brightness was a bit low, so it could be time to replace the backlights. Reading on the 'net made me think that it could have something to do with the firmware, several people mentioned that they had brightness variations that went away after updating. Ok, not really what I had seen but it couldn't hurt could it?
Allright, after updating the brightness is much better and the picture looks very nice. But... It has some weird kind of ghosting. For instance, when I turn on the menu, leave it on screen for 10 seconds and then turn it off, I can still see it in the normal picture, even when I cut the power for 15 seconds and then turn it back on. It's almost like the LCD has a memory of it's own, I have no other explanation for it. And I don't mean standby mode, I really pull the plug from the mains.
I can't remember seeing this before I updated the formware, but really... what's going on?  :-//

Any ideas welcome!

romantronixlab:
When the cover was off, did you check condition of components, mainly the capacitors? I had one Vizio TV acting once because of out of specs capacitors.

PA0PBZ:

--- Quote from: romantronixlab on August 10, 2014, 07:20:49 pm ---When the cover was off, did you check condition of components, mainly the capacitors? I had one Vizio TV acting once because of out of specs capacitors.

--- End quote ---
Capacitors all looked fine, one thing I noticed is that the capacitors at the backlight connection (22p, 6Kv) heated up to 100C, not sure if that is normal...

FrankenPC:
Do LCD's have a internal processor using a frame buffer?  Sounds like the frame buffer mechanism is damaged somehow. 

Rasz:
firmware upgrade fixing backlight brightness is weird enough, sounds like tv goes into some kind of power saving mode? unless it wasnt backlight, but tcon problem

ghosting is tcon related, panel might be overdriven leaving semi permanent post images

firmware upgrade never touches tcon, so I fail to see how upgrading firmware could result in this  bug

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