Alright. I've been trying to chase one thing after the other, combing the forums for some clues, but I'm over my head (which isn't difficult to achieve, sorry to say).
I acquired a Samsung PN51D550 that did the usual 6 blinks, no turn on. I didn't hear startup audio, as once I fixed it, found the previous owner had disabled the internal speakers. I would get Vs and Va ramp up and drop on turn on, with the slow LED blink.
I disconnected the Y-sus from SMPS (and associated cables to the X-main as well), and was able to get stable voltages on the SMPS, and a "normal" pulse from the Logic LED. A quick check of the X-main IC's found the usual compliment of shorts (on ALL the transistors), so I found a replacement and ordered it. While waiting, I checked the Y-sus for shorts and didn't see anything too far out of the ordinary, so I kept it. I don't want to throw lots of $$ at the tv, as I'm repairing this for a young friend w/out lots of $$.
So, new X-main is in, the tv powers on and shows a picture. I was able to set the following:
Vs- 203 Vdc (spec)
Va- 58 Vdc (spec, but found later could only maintain after running for a bit)
Vsc - -193 Vdc (spec)
Ve - 84.3Vdc (lowest I could get it, spec is 83)
I noticed Ve was too high, and since the Ve voltage is supplied by the Y-sus, someone asked me to measure that. Y-sus is supplying 105.3Vdc over to the X-main. On top of this, I'm getting red pixilation on mainly white/light screens, and am not sure if it is associated with the increased Ve voltage.
Other forums said to work with contrast/brightness and other color adjustments, but it didn't seem to make much difference unless I brought the values so low as to make watching difficult. I tried to increase the Vs a bit (to 205Vdc) just to see if it would clear up the spots, but it didn't do much, and I've read enough to know that it's not good for the set to leave it like that for too long. I also read a post mentioning to raise the Vsc to see if it would help, and it didn't.
My questions are whether anyone knows what would make the Ve run on the high side (and is it a problem)? Would it be a possible cause of the "Red mist" (as I'm calling it) on white screens? And if not, where should I start looking to fix the patches of red pixels?
I've attached pictures of the back of the set, along with what will hopefully show the red patches I'm trying to describe! Even if someone could point me to a previous post I may have overlooked, I'd be appreciative!
I acquired a Samsung PN51D550 that did the usual 6 blinks, no turn on. I didn't hear startup audio, as once I fixed it, found the previous owner had disabled the internal speakers. I would get Vs and Va ramp up and drop on turn on, with the slow LED blink.
I disconnected the Y-sus from SMPS (and associated cables to the X-main as well), and was able to get stable voltages on the SMPS, and a "normal" pulse from the Logic LED. A quick check of the X-main IC's found the usual compliment of shorts (on ALL the transistors), so I found a replacement and ordered it. While waiting, I checked the Y-sus for shorts and didn't see anything too far out of the ordinary, so I kept it. I don't want to throw lots of $$ at the tv, as I'm repairing this for a young friend w/out lots of $$.
So, new X-main is in, the tv powers on and shows a picture. I was able to set the following:
Vs- 203 Vdc (spec)
Va- 58 Vdc (spec, but found later could only maintain after running for a bit)
Vsc - -193 Vdc (spec)
Ve - 84.3Vdc (lowest I could get it, spec is 83)
I noticed Ve was too high, and since the Ve voltage is supplied by the Y-sus, someone asked me to measure that. Y-sus is supplying 105.3Vdc over to the X-main. On top of this, I'm getting red pixilation on mainly white/light screens, and am not sure if it is associated with the increased Ve voltage.
Other forums said to work with contrast/brightness and other color adjustments, but it didn't seem to make much difference unless I brought the values so low as to make watching difficult. I tried to increase the Vs a bit (to 205Vdc) just to see if it would clear up the spots, but it didn't do much, and I've read enough to know that it's not good for the set to leave it like that for too long. I also read a post mentioning to raise the Vsc to see if it would help, and it didn't.
My questions are whether anyone knows what would make the Ve run on the high side (and is it a problem)? Would it be a possible cause of the "Red mist" (as I'm calling it) on white screens? And if not, where should I start looking to fix the patches of red pixels?
I've attached pictures of the back of the set, along with what will hopefully show the red patches I'm trying to describe! Even if someone could point me to a previous post I may have overlooked, I'd be appreciative!
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