Lg 50pg20

[jose6326]

I forgot the issues with this tv

So I just removed the back cover

Found a few blown caps on the psu and the ysus board

[jose6326]

Re: Lg 50pg20

Here is a closer view of the blown caps

I haven't tested any voltages because of the blown caps.

Or should I?

What other caps should I replace?
Or should I just replace the faulty ones?

Thanks

[MagicSmoke]

Re: Lg 50pg20

I would change all that are under 100v. It's good insurance that you wont have to open it up again in the near future.

But be aware that the bad ones can cause other parts to fail also. So far I have been lucky on the PSU's that I recapped.


Same on the X & Y replace all under 100v. All of them have the same hours even though they may not have the same stress on them.

Test PSU first after recap to make sure all of the voltages out are to spec.

[jose6326]

Re: Lg 50pg20

Thanks will do

[jose6326]

Re: Lg 50pg20

Ok so I changed the caps

I plugged in the tv and I get a red standby light
There is also a red led on the main board

So I turned on the tv with the remote and the red standby light turned blue
The red led on the main board turned amber
The green led on the logic board turned on and the relay on the psu clicked once

I can hear some static from the speakers as I raise the volume with the remote it gets louder

But I dont have any image on the screen its black

[jose6326]

Re: Lg 50pg20

Here are the voltages

Vsc on the ysus board .382v

Vzb on the zsus board 96v

I could not find the test point for Vs or Va

So I tested at 2 locations

First was on the ysus board (see pic)
Va 65.3v
Vs 192.4v

Second point was at the connector on the psu going to ysus
Vs 192.4v
Va 65.3
Connector going to zsus from psu
Va 65.4v
Vs 192.3v

[jose6326]

Re: Lg 50pg20

After doing some searching I see that theses sets have bad ysus boards and possible faulty buffer boards as well

https://www.badcaps.net/forum/showth...ghlight=50pg20

I did find a blown surface mount fuse on the ysus board below one of the caps I replaced

Should I bother replacing it?

[sugar_ray]

Re: Lg 50pg20

I have this exact set Jose doing the exact same as yours!! Powers on, static can be heard just no pic!! Been on the look out for a new Y board and buffer set. Found lots but all waaaaaaay over priced in my opinion for an out dated tv that only pumps out 720p resolution!!

Still holding out hope if finding a decent price board but may have to just bite the bullit on this one!! Y boards are tough to repair at the component level. Best bet is to find a good working board

[jose6326]

Re: Lg 50pg20

yes these boards are way over priced

on another post I read that sometimes the buffer boards are faulty and not the the ysus

hopefully someone can suggest what components to test on the ysus to figure what is defective
I rather replace a component like a mosfet than the whole board

today I am going to replace the fuse and remove the top buffer board to see if I get any weird colors on the screen

[rccrasher65]

Re: Lg 50pg20

Jose6326, Unfortunately those boards I had were sold, sorry. Be extremely careful when removing buffer board, ribbon cables are extremely delicate. Best of luck on your repair.

[rccrasher65]

Re: Lg 50pg20

After doing some searching I see that theses sets have bad ysus boards and possible faulty buffer boards as well

https://www.badcaps.net/forum/showth...ghlight=50pg20

I did find a blown surface mount fuse on the ysus board below one of the caps I replaced

Should I bother replacing it?

yes

[jose6326]

Re: Lg 50pg20

Jose6326, Unfortunately those boards I had were sold, sorry. Be extremely careful when removing buffer board, ribbon cables are extremely delicate. Best of luck on your repair.

you are correct they are delicate

when I removed the ysus and buffer boards together I had the hardest time pulling the ribbon cables out

I was so paranoid I was going to tear one, luckily I didn't

putting them back in was kind of a pain as well because they kind of have to snap in and pushing them in I almost bent them.

RC I am going to remove the buffer boards just like you did hopefully that will tell me if only have to replace that or the ysus as well

thanks

[jose6326]

Re: Lg 50pg20

Ok so I replaced the fuse from another defective board

I removed the top buffer board and powered the tv on

I get a black top screen and a grey bottom screen

Does that mean the top buffer board is bad?

[jose6326]

Re: Lg 50pg20

I was reading on another thread that if a fuse is blown on the ysus an ipm failed

Tom66

A common fault is for the fuse on the Y-sustain to blow. Most often it blows when one of the IPMs on the Y-sustain fail. These IPMs can be difficult to replace, but the board will certainly cost less than $560!! And it will take less than a half-hour to replace it.

Which fuse would tell me if an ipm failed?

There are 6 surface mount fuses and 1 socket mount fuse

[jose6326]

Re: Lg 50pg20

The fuses in the green tested fine

The fuse in the red is the one that blew and I replaced

[jose6326]

Re: Lg 50pg20

I am confused

I removed the bottom buffer board and put back the upper

Now I get a top screen image and bottom black screen

Which board is defective? Or is the ysus board defective?

Please help

Thanks

[rccrasher65]

Re: Lg 50pg20

Looks like y sus is good, and lower buffer is bad.

[sugar_ray]

Re: Lg 50pg20

You've come along way my friend!! You went from no picture to half!! In the right track for sure!! Your "upper" buffer is working just fine!! Your Y sustain board is priming just fine as well. That only leaves your lower buffer board. Have you tried re-seating the LVD cable on the lower buffer?? If not, a replacement lower buffer may be in order. They won't cost much

[jose6326]

Re: Lg 50pg20

Thanks for the help guys

I want to make sure I order the right part

I figured it would be the lower buffer board

I will reinstall the bottom buffer and hopefully its just the ribbon cables were not seated properly

If not I wilk order the lower buffer

Thanks again

[jose6326]

Re: Lg 50pg20

Sugar ray thanks for the suggestion
I probably would have just ordered a new board

I got a full clear picture

Thanks for the help everyone

Another tv saved from the landfill

Before I put everything back together
Should I test any other voltages?

Should I program some display settings?