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Old 01-15-2022, 04:09 PM   #1
goodpsusearch
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Default LG Flatron L207WT repaired

Got this 8 years ago for 10 euros, seller said he tried to repair psu and destroyed it but panel is OK.

Used panel to fix another LG 20" model LG Flatron L204WS that found near dumpster with broken panel.

Used panel of L207 on L204 and kept L207 for parts.

1 month ago troubleshooted Samsung 20" I also found for free, turned out the Samsung had mainboard bad. Tried to reflow, no change.

So, I decided to use the panel of Samsung and try to fix the LG L207 too.

I attach pics after repair of the power supply that the previous owner tried to fix and did more damage than good.

Noticed that he recapped entire psu board with Jackcons

And to make it worse, he installed the small starter cap with reverse polarity

So, I removed all the Jackcon capacitors and carefully inspected board for broken traces / cold solder joints / ripped off smd components / lifted pads etc, then recapped board using a mix of good caps and mediocre caps like Teapo and Taicon.

I also tried to reinforce some solder traces that act like heatsinks, preventing PCB from overheating.

Monitor works!

Creating thread for future reference
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Old 01-19-2022, 02:29 AM   #2
momaka
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Default Re: LG Flatron L207WT repaired

Nice work!
... and wow, a lot of patience to swap so many parts between so many monitors around. Pretty cool, though.

Quote:
Originally Posted by goodpsusearch View Post
I also tried to reinforce some solder traces that act like heatsinks, preventing PCB from overheating.
I have actually found a really good solution for that: drill holes in PCB where the thick copper areas are and solder solid copper wire on the other side to serve as a heat sink. I did it on this monitor shown here:
https://www.badcaps.net/forum/showthread.php?t=91943
... which I am using right now to post this from.

Quote:
Originally Posted by goodpsusearch View Post
Noticed that he recapped entire psu board with Jackcons
LOL!
I actually did that last week to a 40" Samsung TV PSU board, just to test it out. Glad I didn't invest any more time/parts in it, because the LCD has horizontal dead/dying pixels (slightly darker spots) that don't seem to be induced from user damage. It's only on the lower half of the screen, though, so I'm wondering if I can feed an analog signal into the TV with a smaller vertical resolution, then move the whole image up above the line of the dead pixels and basically use the TV as a monitor. It's a 2007 CCFL beast with no smart features (good!)... so most people don't think it's worth anything.
I may recap it properly, though.
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Old 01-30-2022, 05:18 PM   #3
goodpsusearch
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Default Re: LG Flatron L207WT repaired

Quote:
Originally Posted by momaka View Post
Nice work!
... and wow, a lot of patience to swap so many parts between so many monitors around. Pretty cool, though.


I have actually found a really good solution for that: drill holes in PCB where the thick copper areas are and solder solid copper wire on the other side to serve as a heat sink. I did it on this monitor shown here:
https://www.badcaps.net/forum/showthread.php?t=91943
... which I am using right now to post this from.
https://www.badcaps.net/forum/attach...1&d=1610349543


This is art

Very cool idea, will try it next time. unfortunately, I don't have so thick copper wire but I will see what I can do (improvising)


Quote:
Originally Posted by momaka View Post

LOL!
I actually did that last week to a 40" Samsung TV PSU board, just to test it out. Glad I didn't invest any more time/parts in it, because the LCD has horizontal dead/dying pixels (slightly darker spots) that don't seem to be induced from user damage. It's only on the lower half of the screen, though, so I'm wondering if I can feed an analog signal into the TV with a smaller vertical resolution, then move the whole image up above the line of the dead pixels and basically use the TV as a monitor. It's a 2007 CCFL beast with no smart features (good!)... so most people don't think it's worth anything.
I may recap it properly, though.
I got this for free:

https://www.badcaps.net/forum/showth...97#post1099497

have it sitting on my living room (everyone hates me for the space it takes) more than 1 year, because I feel too afraid/inexperienced/confused to try to repair it

Last edited by goodpsusearch; 01-30-2022 at 05:22 PM..
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Old 02-05-2022, 12:03 AM   #4
momaka
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Default Re: LG Flatron L207WT repaired

Quote:
Originally Posted by goodpsusearch View Post
https://www.badcaps.net/forum/attach...1&d=1610349543


This is art

Very cool idea, will try it next time. unfortunately, I don't have so thick copper wire but I will see what I can do (improvising)
LOL, thanks!

Yeah, the solid core copper wire I used there is standard #14 AWG (roughly equivalent to 2.0 mm^2 solid core copper in EU.) It's the type of wire that's used in household 120V AC in North America for plugs & lightning circuits up to 15 Amps.

Basically, I had a bunch of scraps from various wiring projects... and I *never* throw away wire scraps precisely for reasons/projects like this.

Quote:
Originally Posted by goodpsusearch View Post
I got this for free:

https://www.badcaps.net/forum/showth...97#post1099497

have it sitting on my living room (everyone hates me for the space it takes) more than 1 year, because I feel too afraid/inexperienced/confused to try to repair it
Nice TV!

Sadly, full HD sets under 46-50" have very little value here (can usually get one for $30-50, but occasionally even free.)

Don't worry, 1 year is nothing. I have a 46" Sammy from more or less the same era sitting for 4 years now in the downstairs bathroom. It's behind the door, as that's the only place where it isn't too much in the way of anyone... and I can still easily pull it out when I want to tinker with it. I've been trying all kinds of experiments on it to try and get it working... but none have worked so far. And I still don't know if it's the balancer board or the PSU/inverter that are causing the issues. Unfortunately, the replacement boards are too expensive for my tastes, considering that I don't even watch TV, nor that I can sell it for much. I've been thinking about installing LED strips for the backlight and calling it done... but the power-cycling of the PSU board has me worried that all of this work will be for nothing.

In regards to your TV, watch the YT video that nomoresonys posted, particularly from 1:58 forward. On that note (and I should probably write this in the thread you posted in... but the explanation is kind of long and I have to look at the notes from my experiments to confirm a few things first), the only thing I don't like about that YT video is how the person in it measures the voltages on the transformers on the balancer board. When I did that with my TV, I got nothing like his results. Eventually figured that I can get somewhat meaningful results if I made a rectifier circuit on a breadboard and connected my multimeter probes to it, then feed the rectifier circuit with a probe from each transformer feedback pin on the balancer board to it. This is the only way I could get a stable and consistent (DC) readings on my meter. I also tried removing + bypassing a few transformers like that video showed (or perhaps it was a related video from the same person?), but unfortunately this still didn't reveal which CCFL (if any) had problems. So this thing is back in the bathroom behind the door until next time I have the energy to troubleshoot it more. It's sad, buy I might end up scraping it eventually at some point... which would be a shame, because the LCD TFT is good (though extremely dusty at this point, since it has sat dismantled for a few years as well.)
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