Samsung ue32h4510 turns on and off randomly (bad power board ?)
Greetings fellows, I've searched the forums for this power supply and TV, but I couldn't find anything remotely close, so I'll start my own thread and hopefully we'll be able to fix this TV, as it seems like a real simple thing, but I can't quite pinpoint it.
The problem: a Samsung ue32h4510 Smart bla bla TV turns on and off at random intervals. Sometimes it stays on for longer, sometimes the "Smart" logo flashes on screen for barely a second and then it goes off before rebooting again.
What I found so far: I'm most certain it's a power supply issue. The power board is a BN44-00696A (see the pictures, let me know if you want any close-ups of specific parts). I first wanted to make sure it's not the main board to blame, so I unplugged it from the supply and, like with most Samsungs, the LEDs fired up.....for a while at least, as after a few moments, they started flickering and eventually went out (indicating the same intermittent power issue from earlier). I then wanted to make sure it's not a bad LED to blame, so I did the opposite and left just the board with no LEDs. Using my phone's flashlight, I was able to see the logo coming on and then the fuzz you get when there's no antenna plugged it. Once again, it worked like that for a few moments and then rebooted. My first thought was to reflow the connections to the transformer, diodes and switching transistor. I even pulled out the D-PAK diodes on the back of the board and checked them - they all seem fine and there are no other shorts. I tried the TV again and it almost seemed like I fixed the issue: it stayed on for way longer, but then it went off again (after around 10-15 minutes). I then proceeded to swapping out some caps: I started with the 47uF one near the rectifier bridge (towards the middle-right of the board) and then the two 470uF ones in the upper left (which was useless now that I look at it, since those are tied to the backlight portion which seems to work). I tried it again and this time it seemed even worse for some reason, as the backlight flickered a lot and the TV barely came on - it took 2-3 tries to get it to show anything and then it went through its power cycle again. When it does decide to stay on, I get the correct 12v on the 12v rail, so the secondary seems perfectly fine - it's the primary I'm holding as the main culprit. There's also a whistling noise coming from the coil that's part of the LED drive (only when the LEDs are plugged in, of course), but I'm pretty sure that's normal. Here's the weird part: it only seems to turn off when I touch or bump the power board, which is why I still think there's a bad joint somewhere (though I may be far off). Could it be a bad optocoupler or control IC? Again, please don't go too hard on me if this has already been asked somewhere else, but I have searched the forum and couldn't find something related to it. I'm still new around here and may not know how to correctly use the search function LOL. What do you guys think ?
The problem: a Samsung ue32h4510 Smart bla bla TV turns on and off at random intervals. Sometimes it stays on for longer, sometimes the "Smart" logo flashes on screen for barely a second and then it goes off before rebooting again.
What I found so far: I'm most certain it's a power supply issue. The power board is a BN44-00696A (see the pictures, let me know if you want any close-ups of specific parts). I first wanted to make sure it's not the main board to blame, so I unplugged it from the supply and, like with most Samsungs, the LEDs fired up.....for a while at least, as after a few moments, they started flickering and eventually went out (indicating the same intermittent power issue from earlier). I then wanted to make sure it's not a bad LED to blame, so I did the opposite and left just the board with no LEDs. Using my phone's flashlight, I was able to see the logo coming on and then the fuzz you get when there's no antenna plugged it. Once again, it worked like that for a few moments and then rebooted. My first thought was to reflow the connections to the transformer, diodes and switching transistor. I even pulled out the D-PAK diodes on the back of the board and checked them - they all seem fine and there are no other shorts. I tried the TV again and it almost seemed like I fixed the issue: it stayed on for way longer, but then it went off again (after around 10-15 minutes). I then proceeded to swapping out some caps: I started with the 47uF one near the rectifier bridge (towards the middle-right of the board) and then the two 470uF ones in the upper left (which was useless now that I look at it, since those are tied to the backlight portion which seems to work). I tried it again and this time it seemed even worse for some reason, as the backlight flickered a lot and the TV barely came on - it took 2-3 tries to get it to show anything and then it went through its power cycle again. When it does decide to stay on, I get the correct 12v on the 12v rail, so the secondary seems perfectly fine - it's the primary I'm holding as the main culprit. There's also a whistling noise coming from the coil that's part of the LED drive (only when the LEDs are plugged in, of course), but I'm pretty sure that's normal. Here's the weird part: it only seems to turn off when I touch or bump the power board, which is why I still think there's a bad joint somewhere (though I may be far off). Could it be a bad optocoupler or control IC? Again, please don't go too hard on me if this has already been asked somewhere else, but I have searched the forum and couldn't find something related to it. I'm still new around here and may not know how to correctly use the search function LOL. What do you guys think ?
Attached Files
Maybe one day....So you're saying you started heating up the board and when you came to that inductor it suddenly started working and that gave it away as the defective area ? I too have an inductor there as you can see, but it doesn't make sense, since that's part of the LED driver. Perhaps the same thing could happen to the main FET....will try messing around with the hot air station myself. I've already ordered a new supply (client's request), but I'll try fixing this one too nonetheless - I like a good challenge 
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