TV LG 37LV5500 reflow

I bought this smart TV (LG 37LV5500) set at 2011. At 2015 the problems started. The problem of the TV was that the main processor overheated and lost the connection.

The problem is easily solved by reflowing but only temporarily. After several failed attempts I finally mastered reflowing.

  • I tried the oven method and the TV worked for a month. I even tried to mimic the thermal profile.
  • I tried the heat gun approach and the TV worked for about 1 week.
  • I tried to reball (needs special hardware) and the owner of the reballing hardware talked me out of it. He suggested to buy a new one from e-bay.
  • I bought a replacement board in e-bay but it didn’t work.
  • I finally bought another LG TV with great reservations.

I also found 12v somewhere in the board and added a small fan in order to avoid extensive overheating. The fan must be very thin in order to fit when you try to close the TV. I found that a 40x40x10 was allowing the case to close properly, with a bit of extra pressure. Probably a 50x50x10 or maybe a 60x60x10 fan could also fit in but I wasn’t able to find these fans so there is room for some experimentation.

Enjoy the pictures. The first one shows how to protect the rest of the board (plastic parts etc) by wrapping the board in tinfoil and baker (anti stack) paper. Also I changed thermal paste and replaced the 4 springs with screws in order to make sure the cooler (black metal plate) is hold really tight to the processor.

Definitely a fail but at least I didn’t give up without a decent fight. At the end the local repair shop offered to buy the TV for 40eur.

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APC Back-UPS RS 800 overload problem with no load: Solved

That is a quick and easy fix of a very common problem of APC Back-UPS series.

The problem is that the UPS overload red light is constantly turned on even with no load at all. A google search did not reveal any solution other than the board is faulty and there is nothing you can do about it.

I was handed this UPS and naturally I employed all my google foo in order to save a seemingly fine UPS. This time however the solution didn’t come from google but from youtube. If you are like me then you are totally against the wave of video tutorials that are flooding our everyday life. I prefer a text with properly defined steps than a 15′ video documenting a series of three clicks in order to access the desired submenu.

However in electronics repair hackery it actually makes some sense to present your work in a youtube video. I doubt if it is faster this way but lots of people are actually posting very useful stuff there especially for obscure repairs such as this one.

I am writing the post because the solution is not in a youtube video but in a comment. If it was in the video or in the title then the solution will be findable by google. Instead the solution was in the comment section (yes I read youtube comments – can you imagine that?) in Spanish by Lujan Luis Giaccardi with the picture that shows the faulty capacitors red circled. Totally not findable. So I am posting it here for future reference.apc_rs_800

The comment translated in google translate says:

If you turn on the red light of “overload” you have to change the two electrolytes marked in the photo this:

The youtube video where you can find the original comment is https://www.youtube.com/watch?v=66oKHjCo5AA

Since I am not much of an expert in soldering and removing surface mount (SM) electrolytic capacitors I found (easily this time) another youtube video to figure how to get rid of them. Here it is:

 

I changed the faulty capacitors with normal capacitors and lo and behold! It worked!

Hope that helps.