Before I start, I should probably note this is the same symptoms and make of TV in this thread here:
https://www.badcaps.net/forum/showthread.php?t=22162
I wasn't sure if I should continue posting there, or start a new one as it's a separate repair, since that one had no resolution. 50/50 at starting another. (Not sure how necroposting works here)
This TV has a mainboard that accepts power from a 19v transformer, rather than a 110v line. There appear to be two other boards (one visible from the back, the bottom one) on top and bottom that have ribbon cables going off to them.
Someone happened to create a video that gives a good view of it all:
https://www.youtube.com/watch?v=JJ7M7CLgtdQ
Backstory: Someone threw this out. I saved it from the curb, curious, thinking I'd take it apart and learn something without really expecting to fix anything. A recent Samsung TV failing with an easy capacitor repair has me a bit more optimistic. Or, it did, until I realized how shaky my hand is.
There is (was) no visible damage to the boards. The system would start blinking the power light for about 30 seconds upon getting power, then the light would go off. Pressing the power button after that will bring the power light back on, solid this time. After a few seconds there is a short burst of static, as though it's trying to pull from coax input, getting nothing, and then muting itself. The monitor never shows anything, not even faintly. I suspect, as did the OP in the other thread, that the blinking at start is feedback to indicate the TV has found something wrong with it at POST. Thinking about it now I should probably count the number of times it blinks when I next plug it in.
I should note I'm a computer scientist. I don't have any electrical engineering background. This is my foray into that. I've my HAM tech license, so I know enough to be dangerous. I do own a Weller WESD51 variable soldering iron, but I'm not very good with it yet. It's become very apparent that using these irons is an art I've a long way to go to master. My only real experience with them was soldering LEDs to bell wire to create low-voltage landscape lighting for the new patio I built. (+$40 a light for patio lights? Get outta here! They're just lit spider-houses! The lights are a buck online! I saved myself hundreds. Anyway)
I try to do my research. I've read the PDF at the top of this forum. I've watched some videos (This one was awesome for me: https://www.youtube.com/watch?v=cNFzBJELFoU ) regarding how to trace where the power is going, and at what voltage to see where your defective part is, but I'm still largely in the dark about what most of the components are, or how they connect to one another.
Unfortunately while testing the components I could identify I glanced over at the voltage while testing a regulator and there was a spark and a pop. There's a scorch mark on the reg lead and part of my multimeter's positive probe is melted...or maybe that's part of the regulator. I have to learn how people keep their hands so still. I'm not sure what I did, but I assume I bridged that tab with another using the probe, despite the damage being on the tab I was originally touching. It was the positive lead. The negative lead was grounded. Perhaps that was wrong. As mentioned, first time doing this and don't mind making some mistakes as that just gives me more time practicing repair of parts.
That said, that regulator likely needs replaced now, so I'll find and order one. (or 10) I'm glad I tested the fuses near the power plug first, as they certainly registered 19v on both sides before that fiasco, and one certainly doesn't anymore. So I get to replace it as well. Another regulator near the first now registers the same voltage as the blown fuse, when it previously registered 19v on that tab, as the other did.
I'm sorry I didn't test the components on the bottom board before that though. They presently read 11v when power is given to the system, but I can't say that's what they're supposed to get.
All this said, what might be my next step in diagnosing the issue preventing the monitor from displaying something? Is there another video I might watch to help me understand more about how to troubleshoot the repair of TVs/Monitors that you would recommend?
TvBob fixed his by running 19v lines to the LED bar I've yet to uncover on my TV. It seems the OP was likely running into a similar issue with his last post. I Think I understand what he did, but not sure where he pulled the power. Prior to trying that I'd like to confirm that's the issue.
I realize this was a long read and so I thank you for your time in doing so. Any and all advice is appreciated.
I'm aware finding a replacement board online is an option and would likely fix my issue (I believe I read someone doing just that in my research) but frankly--I don't need anymore TVs. I'm doing this to learn and to prove to myself that I can.
Thank you.
https://www.badcaps.net/forum/showthread.php?t=22162
I wasn't sure if I should continue posting there, or start a new one as it's a separate repair, since that one had no resolution. 50/50 at starting another. (Not sure how necroposting works here)
This TV has a mainboard that accepts power from a 19v transformer, rather than a 110v line. There appear to be two other boards (one visible from the back, the bottom one) on top and bottom that have ribbon cables going off to them.
Someone happened to create a video that gives a good view of it all:
https://www.youtube.com/watch?v=JJ7M7CLgtdQ
Backstory: Someone threw this out. I saved it from the curb, curious, thinking I'd take it apart and learn something without really expecting to fix anything. A recent Samsung TV failing with an easy capacitor repair has me a bit more optimistic. Or, it did, until I realized how shaky my hand is.
There is (was) no visible damage to the boards. The system would start blinking the power light for about 30 seconds upon getting power, then the light would go off. Pressing the power button after that will bring the power light back on, solid this time. After a few seconds there is a short burst of static, as though it's trying to pull from coax input, getting nothing, and then muting itself. The monitor never shows anything, not even faintly. I suspect, as did the OP in the other thread, that the blinking at start is feedback to indicate the TV has found something wrong with it at POST. Thinking about it now I should probably count the number of times it blinks when I next plug it in.
I should note I'm a computer scientist. I don't have any electrical engineering background. This is my foray into that. I've my HAM tech license, so I know enough to be dangerous. I do own a Weller WESD51 variable soldering iron, but I'm not very good with it yet. It's become very apparent that using these irons is an art I've a long way to go to master. My only real experience with them was soldering LEDs to bell wire to create low-voltage landscape lighting for the new patio I built. (+$40 a light for patio lights? Get outta here! They're just lit spider-houses! The lights are a buck online! I saved myself hundreds. Anyway)
I try to do my research. I've read the PDF at the top of this forum. I've watched some videos (This one was awesome for me: https://www.youtube.com/watch?v=cNFzBJELFoU ) regarding how to trace where the power is going, and at what voltage to see where your defective part is, but I'm still largely in the dark about what most of the components are, or how they connect to one another.
Unfortunately while testing the components I could identify I glanced over at the voltage while testing a regulator and there was a spark and a pop. There's a scorch mark on the reg lead and part of my multimeter's positive probe is melted...or maybe that's part of the regulator. I have to learn how people keep their hands so still. I'm not sure what I did, but I assume I bridged that tab with another using the probe, despite the damage being on the tab I was originally touching. It was the positive lead. The negative lead was grounded. Perhaps that was wrong. As mentioned, first time doing this and don't mind making some mistakes as that just gives me more time practicing repair of parts.
That said, that regulator likely needs replaced now, so I'll find and order one. (or 10) I'm glad I tested the fuses near the power plug first, as they certainly registered 19v on both sides before that fiasco, and one certainly doesn't anymore.
So I get to replace it as well. Another regulator near the first now registers the same voltage as the blown fuse, when it previously registered 19v on that tab, as the other did.I'm sorry I didn't test the components on the bottom board before that though. They presently read 11v when power is given to the system, but I can't say that's what they're supposed to get.
All this said, what might be my next step in diagnosing the issue preventing the monitor from displaying something? Is there another video I might watch to help me understand more about how to troubleshoot the repair of TVs/Monitors that you would recommend?
TvBob fixed his by running 19v lines to the LED bar I've yet to uncover on my TV. It seems the OP was likely running into a similar issue with his last post. I Think I understand what he did, but not sure where he pulled the power. Prior to trying that I'd like to confirm that's the issue.
I realize this was a long read and so I thank you for your time in doing so. Any and all advice is appreciated.
I'm aware finding a replacement board online is an option and would likely fix my issue (I believe I read someone doing just that in my research) but frankly--I don't need anymore TVs. I'm doing this to learn and to prove to myself that I can.
Thank you.
