Troubleshooting LG Flatron M4715CG

[dysfunk]

Hey guys.
I just recently purchased a second hand LG Flatron M4715CG for $50. It is a unit that was used at Fox 8 News that they were throwing out because of power supply issues.

I really don't know much about the technical standpoint of electronics but I would love to try and fix this thing myself.

Background:
The day I got it, I hooked it up to my computer and it worked fine. That night, I powered it down, but left it plugged in. The next day, I was going to use it again, so I powered it on and it displayed normally for 5-10 seconds - the screen then went black. I cannot tell if the backlight is on or not. What I can tell you is that the LG logo on the bezel will flash every five seconds, followed by an electronic click. Now, it doesn't display anything, just goes straight to the flashing of the LG Logo.

*edit* The power indicator light is amber when it first comes on, then goes away and doesn't turn blue or green, whichever color it's supposed to be.


At the moment, I am just wanting to determine what the issue is, or at least rule out what it's not. If it would be helpful, I can take a video of the issue.


I stumbled upon this thread, but wasn't sure how relevant it was. https://www.badcaps.net/forum/showthread.php?p=277325

Thanks,
Clint

[selldoor]

Re: Troubleshooting LG Flatron M4715CG

A good start would be to "EDIT" the other thread down to "double posted in error" then save it. Then click on the red triangle with an exclamation mark in it and ask a Mod to delete it ( bottom left margin)

[dysfunk]

Re: Troubleshooting LG Flatron M4715CG

I've edited it. I didn't mean to double post.

[selldoor]

Re: Troubleshooting LG Flatron M4715CG

Ok - it happens- This is more like a TV without a tuner than a monitor. Do you have a multimeter and soldering equipment. If your "insides" are the same as in the thread you refer to it is often the inverter boards that fail ( In Televisions). Without doing some tests it is hard to tell what might be wrong.
If you post pictures please post using manage attachments - will take jpgs up to 3mb

[dysfunk]

Re: Troubleshooting LG Flatron M4715CG

Attached are some photos. First photo is the layout of all the boards. The rest are all pictures of the power board. The last picture is the connector in which I found some corrosion on.. I didn't see any burns on the board or any bulging/leaking capacitors.
Although, I did find some white silicon/glue or something on some of the capacitors/resistors.. not sure if that was intentional or if that's leakage?


I do not have a multimeter to be able to test. I could however go buy one.

the corrosion/burn on the pin connector is on the ground side. if that helps.

[dysfunk]

Re: Troubleshooting LG Flatron M4715CG

After getting video, the screen does flash as well with the LG logo. Sound like it may be the inverters, possibly?

Video link: http://youtu.be/D6ukct1fv_0

[selldoor]

Re: Troubleshooting LG Flatron M4715CG

I cant tell which socket/pin has the corrosion - what do you mean by "the ground side"
is that what it says on the board?. You need to clean it up and make sure you have connectivity.
You really need a meter to be able to do much.
If this is likely to be a one off repair event a cheap $5-10 one will do.

[dysfunk]

Re: Troubleshooting LG Flatron M4715CG

I will get a cheap meter, this isn't going to be a hobby of mine or anything. I just want this thing to work.

I edited the above post with the video of what the monitor/tv is doing.

On the board where that socket/pin goes, it is labeled |_Ground_||_xxx_|
(xxx) for whatever it may say, I don't remember off the top of my head.

The second pin location on the socket is green/black in and surrounding the pin. It's the only thing I saw that didn't look right on either board. I haven't taken the inverter boards out yet to inspect.

[selldoor]

Re: Troubleshooting LG Flatron M4715CG

Could it be that it has been marked to help establish which way in it goes?
Does it look burnt or corroded or could it be dye/felt tip

[budm]

Re: Troubleshooting LG Flatron M4715CG

Can we get good clear and focused straight shot picture of the whole power supply board both side? Also close up pictures of the connectors on the power supply board, it looks like there are some labels on the connectors to tell use the pin out of the connectors. You will have to report the DC Voltage readings with label of each pin of those connectors when the TV is off and when TV power switch is activated.
It looks similar to this one:
http://www.shopjimmy.com/lg-eay40505...wer-supply.htm