42pj350 all voltages - no display

[ajshoe]

Have a LG 42PJ350 that has all PSB voltages after 2 clicks. The 15V that is generated from the YSUS bd comes up to 18v and then slowly drops down to 4.1V. The 5V from the PSB is there solid - also on the Ysus bd to the logic bd. Have checked buffer bd, Ysus bd, Zsus bd, logic bd, PSB. Have replaced Ysus bd, PSB, buffer bd, logic bd, and no luck. Remote works good - set turns on and off. When first turned on - set makes a buzzing noise for about 3 seconds (same amount of time the 15V line is around 18.1v). anybody seen this symptom ? About ready to dump this set.

[ajshoe]

Re: 42pj350 all voltages - no display

pics of boards

[ajshoe]

Re: 42pj350 all voltages - no display

Ive worked on some samsung plasmas that were really frustrating but this one is topping them. Want to believe the display panel is bad but my gut says its not. DOn't know what else to try - replaced about every board

[ajshoe]

Re: 42pj350 all voltages - no display

I've have now replaced SMPS, logic, Ysus, Xsys, buffer bd, checked all cabling, same symptoms - all voltages are good except 15V from Ysus bd. something is telling Ysus bd to kill 15V line.

IS THIS A BAD PANEL ??

[sordids999]

Re: 42pj350 all voltages - no display

So are you saying the following voltages are good

VS/VA/VSC etc ??
Are you sure the replacement ysus board is good ?

[ajshoe]

Re: 42pj350 all voltages - no display

ill check again but all voltages are good. Ysus is from ebay who guaranteed bd was good (had a display screen with lines in it), turned on set in dark and noticed the screen shows a 2 mm vertical line at the far right side about 6 inches long on the very edge of the display (near Zsus bd). only stays on the same amount of time the V15 line is good (2 seconds). going to change SMPS now again and try it. test patterns does same thing. new SMPS - same thing
measured VS = 205V, Va = 60.1V, Vsc = 7V

on Ysus bd - 15FL with ground on floating ground off buffer bd is 0.1V, 15FL is 0 V
starting to believe my panel is bad or cracked

[sordids999]

Re: 42pj350 all voltages - no display

VSC is low

[freakaftr8]

Re: 42pj350 all voltages - no display

+1. Check buffer boards for shorts. Unplug both buffers in check VSC

[ajshoe]

Re: 42pj350 all voltages - no display

only has one board. been checked twice. i also replaced with new buffer board. same result.

[sordids999]

Re: 42pj350 all voltages - no display

I'm still thinking your have a problem with the ysus or even the buffer board

[ajshoe]

Re: 42pj350 all voltages - no display

I highly doubt that's the issue I have three Ysus boards they all do the same thing. One of the Ysus boards i bought was brand new. I have two sets of buffer boards that have been checked thoroughly. Any of those boards put in there give me the exact same results.

[emoniz]

Re: 42pj350 all voltages - no display

HI!
Just read many posts related to this TV and mine was like:
Sound and everything works but no image. Voltages on the panel are correct and 15V has 18V ok. Looking for the control board and the led don't light up, so with the set working, i tried to put some pressure in control board XD IC and suddenly the led on ctrl board started blinking and image appeared. I must assume this is a ctrl board with bad XD IC bga joints and it should be replaced.
This is only another testemonial to confirm that when you have all voltages and no image it must be ctrl board fault.
Regards and thanks for all the sharing!

[zen]

Re: 42pj350 all voltages - no display

Hi

Yes , your quite possibly looking at poor ball connections on B G A chip .

Unless you have a re-ball station , a replacement control board is required.

Also , normally there is some sort of blink code with L E D S on control board , that may give indication of faulty board , for future reference .

Regards X e n.