LG 50PK550 clicking - plasma newbie

[vinceroger69]

Re: LG 50PK550 clicking - plasma newbie

hopefully reece or budm etc may have some ideas where too look next im still learning myself so not sure what to advise as never worked on this psu before

[jason424]

Re: LG 50PK550 clicking - plasma newbie

hopefully reece or budm etc may have some ideas where too look next im still learning myself so not sure what to advise as never worked on this psu before

Well I appreciate your help and time spent with me thus far

[vinceroger69]

Re: LG 50PK550 clicking - plasma newbie

what i dont understand is before you fitted that ic you had a led on plus a clicking noise so part of the psu was working now your getting nothing.

[jason424]

Re: LG 50PK550 clicking - plasma newbie

The IC and that diode is the only things I monkey'd with. And the orig diode was ok in the first place. I'm tempted to remove the IC and the diode and put the old ones back and see if it returns to clicking.
Unfortunately I can't find a replacement board, or I would contemplate just throwing a new one in.

[vinceroger69]

Re: LG 50PK550 clicking - plasma newbie

maybe worth swopping back as you suggest just be carefull of the solder pads when you remove the ic maybe once the ics removed clean the board and upload a picture of the pads etc just incase theres a break etc

[virpek]

Re: LG 50PK550 clicking - plasma newbie

Hello! Use 20V DC setting on your meter

[jason424]

Re: LG 50PK550 clicking - plasma newbie

So I de-soldered the old IC and found that there were pretty much no solder pads present at any of the thru-holes, much like the pic of the break earlier.
I installed a new IC that I had received later (from China) and installed jumpers (orange and blue dots) and now get 3 clicks over and over when plugged in to power.

EDIT: unfortunately I forgot to take pics of the board after cleaned/removed old IC

[jason424]

Re: LG 50PK550 clicking - plasma newbie

So since I figured I had messed the board beyond repair, I ordered a replacement...from the UK...which arrived today. The set powers on, flashed gray screen a couple times then no pic. Seemed to stay on as the red optical port continued to glow until I hit the power on the front. I can hear a faint hum/buzz on the board.
I test the Va and Vs test points with the TV powered on and I get 130.8 and 187.2 then up past what my meter reads. I thought the Va number was high since the white sticker says 60v for Va and 203v for Vs.

I have also noticed new behavior on the control board...the green LED does 3 short blinks then 1 long blink.

[jason424]

Re: LG 50PK550 clicking - plasma newbie

So I just went to test the Va and Vs voltages and they were very close to the sticker (60/203) at 59 and 198. I also noticed that the green led on the control board was blinking 1 long 1 short then 1 long 1short again, then a pause. I measured the voltages of the connector from the power board to the main board as shown in the pic attached and got the following:
Set plugged in but off:
17v: 0.00
Gnd: 0.00
5.1: .4
5.1: .5
Gnd: 0.00
Gnd: 0.00
Stby: 3.4
AC det: 0.00
Auto Gnd 0.00

Tv powered on:
17v: 16.8
Gnd: 0.00
5.1: 5.1
5.1: 5.1
Gnd: 0.00
Gnd: 0.00
Stby: 5.1
AC det: 2.4
Auto gd: 3.3

I powered off the set and back on again and got the same led blinking scenario as I did before with the 3 short blinks and 1 long blink.

I'm not sure if this replacement power board is bad or if now there is something else wrong?

[jason424]

Re: LG 50PK550 clicking - plasma newbie

Any insight any one can give on further testing to diagnose if its another board or if the replacement is no good?

[vinceroger69]

Re: LG 50PK550 clicking - plasma newbie

im not sure what the blink code means maybe reece has a idea what you can check now as a replacement powersuply sounds like you may have another fault now on a diffrent board i wonder if you can run the test patterns if lg has this feature.

[jason424]

Re: LG 50PK550 clicking - plasma newbie

I feel like a complete moron (what would the equivalent be in the UK? berk?).

I went to go test the board settings again and plugged it in and turned it on. This time I flipped it up against a wall to see the full screen instead of just seeing the edge from underneath when it's hanging off the edge of the bed. Well....it turned on. And the "No Signal" notification was floating around the screen. I obviously didn't see it when it was just the lower edge and assumed the panel was off. So the replacement board from the UK was good and the TV works as it did previously with no image color issues or speckling.

But, as this is my first plasma I've worked on/replaced board, is there any adjustment to the Va/Vs voltages that should be done before moving this to my parents house?

[vinceroger69]

Re: LG 50PK550 clicking - plasma newbie

moron a good word we do use that as well in the uk and as this is a replacement power supply i would check all voltages match the panel sticker if not you can carefully alter them too match but mark the pre sets first with a marker pen just incase altering the voltages causes screen issues (dots etc) and turn them really slowly as dont want too go high and risk blowing parts.

[jason424]

Re: LG 50PK550 clicking - plasma newbie

Yeah they are real close so I don't think I'm going to monkey with them. A big thank you to you and everyone else that stuck through all the pages of posts to help me. I really appreciate your kindness and patience while I try to learn.

[vinceroger69]

Re: LG 50PK550 clicking - plasma newbie

yes being that close i wouldnt adjust them if causing no screen issues and glad the psu replacement fixed the issue sometimes even the best of engineers get stuck and have to replace boards as your had lifted traces/pads was probably the best way forward anyway.

[jason424]

Re: LG 50PK550 clicking - plasma newbie

yes being that close i wouldnt adjust them if causing no screen issues and glad the psu replacement fixed the issue sometimes even the best of engineers get stuck and have to replace boards as your had lifted traces/pads was probably the best way forward anyway.

Well and since that old board is done now...I can practice on removing components without ruining traces/pads for future projects.

[vinceroger69]

Re: LG 50PK550 clicking - plasma newbie

some times you cant help lifting the traces but you will get better with practice its just getting the correct heat not too long or too little and adding fresh solder first in my opion always helps with removal.