LG 17LX1R red standby turns green briefly then red again

[junkmansam]

Took this cute little TV/monitor apart today to find smoke residue inside over the area of the power caps. Clearly the caps are blown from these pics but I'm wondering if the previous owner kept the TV plugged in after realizing something was wrong and in turn causing more damage than just the caps.

Next the one of the main large caps is a brown area near unidentified components. A suspected problem it looks bad. I wanted to get the qualified opinions before sarting my shotgun repair.

[Dgtech]

Re: LG 17LX1R red standby turns green briefly then red again

Yeah that D102 got a little warm. You'll have to check it with a meter to see if it's still good. It may be ok. If you want, get a replacement whenever you order your caps, it wont hurt to change it. It's a cheap part.

Diodes are easy to check. One direction should show high ohms, the other direction should show zero ohms.

[Dgtech]

Re: LG 17LX1R red standby turns green briefly then red again

By the way, excelent pictures. What is the model of your camera? I have to ask.

[junkmansam]

Re: LG 17LX1R red standby turns green briefly then red again

By the way, excelent pictures. What is the model of your camera? I have to ask.

Don't laugh, Canon A400. I use it so much I do believe I have become its master. Thanks for the input, I appreciate it.

[Dgtech]

Re: LG 17LX1R red standby turns green briefly then red again

Yeah, I haven't used mine as much as I wish I did. My pics come out just OK where as you're 3.2 MP camera clearly outdoes my 7.2 Sony.

[junkmansam]

Re: LG 17LX1R red standby turns green briefly then red again

Ok, so I tested the 2 diodes in question and the D102 gave a high reading on both sides. The other one had a high and low side. The D102 is a lt400 1n4007 and I'm having a hard time locating a source for it.

Also, I went a little too hot with my solder station and the PCB around one leg of the diode got a little flakey. Looks like it will settle down once I re-solder the new diode in, at least I'm hoping it will.

[b700029]

Re: LG 17LX1R red standby turns green briefly then red again

1N4007?

http://www.jameco.com/webapp/wcs/sto...de=WSF&CID=GMC

You have to buy at least 10 of them, but they're REALLY cheap.

[PlainBill]

Re: LG 17LX1R red standby turns green briefly then red again

1N4007?

http://www.jameco.com/webapp/wcs/sto...de=WSF&CID=GMC

You have to buy at least 10 of them, but they're REALLY cheap.

And REALLY unsuitable for anything but the mains rectifier on a SMPS. You need a fast recovery or ultra fast recovery diode.

PlainBill

[junkmansam]

Re: LG 17LX1R red standby turns green briefly then red again

Thanks Bill. I was leaning towards getting a fast recovery because they looked more like the one I pulled but they all said 1000v and was wondering if thats too high? I'm hoping to keep this out of the landfill.

[PlainBill]

Re: LG 17LX1R red standby turns green briefly then red again

Thanks Bill. I was leaning towards getting a fast recovery because they looked more like the one I pulled but they all said 1000v and was wondering if thats too high? I'm hoping to keep this out of the landfill.

The voltage rating of a diode is the reverse voltage it can withstand (with a bunch of qualifiers). Good practice dictates the voltage rating is much higher than the output voltage. Off the top of my head, I'd specify a diode rated for at least 3 X the voltage I was rectifying, probably a lot higher; the cost difference is trivial.

As an example, for the 1N4000 series (which I believe are unsuitable for this application), the 400V version costs $.46, the 1000V version costs $.47.

PlainBill

[RobH2]

Re: LG 17LX1R red standby turns green briefly then red again

Did it fix the problem? I have the same issue. The LED is mostly red but it goes green ever so instantaneously and then mostly red for about 4-5 seconds.

I'm not a repair tech but I know my way around soldering and circuits. I can solder and wire but I don't know what does what per se. I have no problem taking it apart and putting it back together but if the caps or components don't show any damage I don't know where to start. If the components you photographed did in fact fix it then I'd take mine apart and replace them even if they show no damage. If it runs then great. If not then all I've wasted is a little time and I'll go buy a new TV. I'm not inclined to pay a repair shop $150 to fix one bad component.

[PlainBill]

Re: LG 17LX1R red standby turns green briefly then red again

Did it fix the problem? I have the same issue. The LED is mostly red but it goes green ever so instantaneously and then mostly red for about 4-5 seconds.

I'm not a repair tech but I know my way around soldering and circuits. I can solder and wire but I don't know what does what per se. I have no problem taking it apart and putting it back together but if the caps or components don't show any damage I don't know where to start. If the components you photographed did in fact fix it then I'd take mine apart and replace them even if they show no damage. If it runs then great. If not then all I've wasted is a little time and I'll go buy a new TV. I'm not inclined to pay a repair shop $150 to fix one bad component.

Why use a shotgun when a soldering iron and DMM are much more precise? Remove the diode and test it. If it's shorted, replace it. If you want additional help, post pictures of YOUR board. One of the top of the power supply, one of the bottom, and attach to your post using 'Manage Attachments' - below the text entry area.

PlainBill

[RobH2]

Re: LG 17LX1R red standby turns green briefly then red again

I hear ya Bill. I will do that at some point. I'm going to be traveling for about 3 weeks. I'll tackle it when I get back. I'll let you guys know if I have issues. I'm not timid...we'll see what happens...

Thanks...