Re: lg 60pz550 black screen, no power, etc
Thing wont come on in test pattern at all now. top heat sink on upper buffer board is super hot now.
Im wondering if something else is wrong. cant get any response with a test pattern, unless i remove lower buffer board. I dont know if lower board is fried again. Im tired of playing with it. I was trying to get it fixed for someone that is having a rough time, was going to give it to them
legonch
Member
Last Activity: 03-26-2019, 09:34 AM
Joined: 02-15-2019
Location: berthoud, co
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Re: lg 60pz550 black screen, no power, etc
ugh.
Okay. Guess ill pull all the boards off and try and sell them on ebay.
Throw the rest away. Dang. Not sure how that cable got ripped like that. It flipped behind the connector, and i just pulled it out really slow, beats me. Total bummer. Thank you again for your help!Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
lower buffer board came in today.
installed it. TV went into the test patterns. Most of the screen looked great. However there were two horizontal lines on the bottom third of the screen that were black. One line was about 1/2 thick, the other, looked to be just a single pixel.
So, went to remove lower buffer cables to make sure they were all hooked up correctly. Noticed this crack in one of the brown flat cables that hook up to the lower buffer board.
Also, the black locking tab on the ysus...Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
Thanks for the reply.
I didnt adjust anything. I wouldnt know where to adjust any voltages.
I ordered a lower buffer board. I agree the screen still seems like there is an issue somewhere, all the pixels arent lit up. They seem to move around if that makes any sense. Like some coming on some shutting off.
I will check in when the board gets here. Thank you again for all your help so far!Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
Further testing continues. I removed the upper buffer board on the left side of the ysus board. TV remained the same. Reinstalled this board.
Middle heat resistor on the lower buffer board has been getting super hot. Removed the lower buffer board. TV now will run a test pattern type on the upper part of the screen. Attached are the pics of the test pattern.
The two chips under the middle heat sink have heat damage on the back side of the board. Im suspect this is the issue. Recommend just replacing board?...Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
Okay, did the heat gun over the chip on low for 45 seconds. Just to the point I stated smelling something.
Waited 30 minutes, reinstalled the board, and tv is still the same.
I did put the usb wireless internet into a port. blue light came on, normal.
Blacked out the living room, turned the tv on, and do not see any light on the screen.
The red light on the front of tv lights up every time i hit a button on the remote.
Am I overlooking something really simple here?...Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
found it, under the heatsink. Nice.
followed the schematic, all the items it said to check, checked out with proper voltages, etc. Schematic says replace the chip.
Ill get out my heat gun, and warm it up slow, and on low. hopefully that fixes this.Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
found a service manual schematic. going through the flow chart, tells me to check L412. Downloaded a pic of the board, and I cant find it anywhere, can find L411, no 412. Any ideas on location?Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
I tried that last night. really dark in the house. really couldnt see any screen change with the power on. Screen seems to stay the same, power on or off. I can try tonight in total darkness
I'll blast the heatsink in the mean time.Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
I hear both sus boards humming when powered up. Guess thats good. So do I test now for continuity on certain parts?Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
Okay, first off, I apologize for driving you nuts.
Secondly, im and idiot. Volt meter was in ac mode......yeah, head slap!!
So,
5v has 5 volts
VA has 54.7
VS 201.6
These read the same on both sus connectors top left and top right
Across the capacitors, 390 volts.Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
[B]You did not answer my question about voltage across the large high voltage capacitors.
[/B]
The black capacitors in the middle of the power board, all read 2-3 volts across the pins while the tv is powered on. I tried the new power board, and the old power board. Same results on the capacitors, 2-3 volts is all.
[B]In previous posts, you said that you have voltage at VA? You stated you have no voltage at VS? Now you do not have either voltage present?[/B]
I initially get a rise in the 5v...Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
The voltages at 5v, VA, and VS are the exact same as in my previous posts. the 5v goes to 2.8-3.5 volts upon powering up, then drops to zero within two seconds. VA and VS have no voltages. And yes Im still testing to chassis ground. Im measuring these on the power board, on both sus connectors. Ive checked and rechecked the diodes, and can not find a short.
Reading more about this on the internet, could this issue be the main board? I have used the test outlined where you disconnect the flat cable on they...Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
Any help here?Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
any help? kinda stuck hereLeave a comment:
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Re: lg 60pz550 black screen, no power, etc
bumpLeave a comment:
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Re: lg 60pz550 black screen, no power, etc
Update.
I ordered a new power board. I couldnt find anything off following your instructions.
New power board installed. All cables hooked up except the ysus and zsus boards.
Redid all the solder I initially did. Totally clean nice solder job now.
I still have the same condition. The voltages measured at the 5v, Va, and Vs are exactly the same as when the other power board was installed. Also the voltages on the fuses remain the same. Lower fuse on power board reads 120, the other...Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
Also, please re-solder the HEATSINK solder tabs and maybe the transistor legs because from the cracked pad with a black circle around it in your first picture, you also have poor solder connections at other locations on the board.
I didnt even see that until you mentioned that!!! Nice Catch!Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
okay, thanks!! i didnt remove the old solder, i just heated the pins up and melted new solder on it.
Would these have anything to do with the power board voltages not being correct? I do get continuity through all of these new soldered joints if that means anything.....Leave a comment:
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Re: lg 60pz550 black screen, no power, etc
Here are the pics of my soldering on the sus boards.
The last pic, the board looks discolored for lack of better terms on the back side, is that the way it is supposed to look?
Thanks!!!...Leave a comment:
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