Lg 60pa5500

[danielh]

I have an LG 60PA5500-UG

I was watching TV the other day and the TV just turned off on it's own. I turned it back on and I had sound but no picture. I left the TV off for a few hours and tried it again. It came one picture and all for about 15 mins and went off again. I turned it back on again and had sound but no picture. About a week later I decided to take it out to my shop and work on it, I plugged it in and it worked just fine. I connected my laptop via HDMI to all 3 ports and the darn TV worked just fine for 7 hours straight with not even a glitch. I turned it off and back on a few times and it worked just fine. The next day I tried it again, the TV came on just fine and about 12 mins in the TV turned off on its own again. I turned it back on and it came on with sound and picture for about a min and went off again. I turned it back on and now I'm getting sound and no picture.

Can someone please help me with this

[R_J]

Re: Lg 60pa5500

Start by taking the back off, check for poor plug connections, there could also be poor solder connections on the power supply or ysus and zsus boards, check the voltages on the plugs when its working and when its not.
Take a couple pictures of the boards with the back off so we can see what we are dealing with

[tvtimmy]

Re: Lg 60pa5500

Cracked solder joint(s) on power supply. Check transformer joints and parts mounted on heatsinks. I would touch up everything with lead solder. If after all the soldering fails to solve the problem check C802 on power supply. Its glued to a transformer under the VS test point.

[Nick's Tvs]

Re: Lg 60pa5500

For this model, we have seen two different parts cause this failure.
The first one is Y-sustain, and the second is the main board.
I would suggest taking the back off, and turning the TV on. With a hair dryer or hot air gun, heat up the BGA chip while it is on for about 15 to 20 seconds. If the TV stays on, leave it on for another 3-5 minutes and try again. If this causes the TV to turn off, then we have found a bad main board. If it does not cause the set to loose picture or turn off, then we have a failure somewhere else.
As Tvtimmy has suggested, check for cracked solder joints on the power supply, the Y-sustain and Z-sustain as well.

[danielh]

Re: Lg 60pa5500

Where is the BGA chip?
Which one is the main board?

[danielh]

Re: Lg 60pa5500

Where is the BGA chip?
Which one is the main board?

[tvtimmy]

Re: Lg 60pa5500

Pic 1 is the mainboard, the one where the hdmi and other ports are. In the center of it there is a black metal heatsink. The bga chip is under it. Have you looked for bad solder yet?

[danielh]

Re: Lg 60pa5500

I took it off and looked but I haven't found any loose connections but a majority of the solder joints have a yellowish color to them almost looks burnt.

[tvtimmy]

Re: Lg 60pa5500

I would still re-solder everything you can on the power, ysus, and zsus boards. try that and if you still jave the same problem check the capacitor I mentioned earlier out of tje circuit.

[mmartell]

Re: Lg 60pa5500

Pic 5 - redo all the joints under the transformer (yellow box)

[Muffmuff]

Re: Lg 60pa5500

I have the same problem with my tv. It can work for a month and the it starts to turn off itself. If I turn it on directly i only get sound but no picture. If I wait for like 30 min it starts like normal but the often works for just some minutes.
I have located two bad caps (see pic) I tested with replacing those two but same spec 50V, 100μF but was lower on heat and was only 85c instad of 105c that I was replacing. TV worked for 2 days but now same error. Cant see that the new ones has gone bad. I saw a guy on youtube recommending checking the mosfets for shorting and I have 3 in line that has pins that is shorted to ground (see blue box on pic). Right now I have a hate-love relationship with this TV

Any suggestions what I should do next would be appreciated.

[tvtimmy]

Re: Lg 60pa5500

Pull the 3 IGBTs that appear shorted and check them again.if they are bad, replace them.

[Muffmuff]

Re: Lg 60pa5500

Pull the 3 IGBTs that appear shorted and check them again.if they are bad, replace them.

Ty for your input. Ive resoldered the new caps, coils and transformer. Has been working since then "fingers crossed".