I have a LG 55LM8600 that stopped powering up after a storm. From previous experience and reference another post (link below) for the same issue, I replaced the power supply board and main board, but still no luck, same symptoms. I have not checked voltages etc. as I was ok with throwing boards at it based on the information at hand. Any other suggestions on what this could be?
[url]https://www.badcaps.net/forum/showthread.php?t=56335&highlight=lg+55lm8600[/url]https://I have a LG 55LM8600 that st...her post (link
damiane
Member
Last Activity: 09-10-2017, 11:08 PM
Joined: 05-31-2013
Location: Houston, TX
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LG 55LM8600 does not power up..three flashes of power light
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Re: LG 50PQ30C-UA No picture - blank PDP
PPosey, Sounds like a similar issue, except for on mine the green LED on the control board was flashing indicating it was working. In my case the Y-SUS and Upper and Lower driver board being replaced solved my issue. Have you taken any voltage readings. Record Vsc, Vy and Va...and I guess Vzb while you are at it, with and w/o the Y-SUS connected and see what's in and out of range. Then we can go from there. Use the attached file to help you with your troubleshooting.... -
Re: LG 50PQ30C-UA No picture - blank PDP
Can you elaborate a bit more on the intermittent failure? Does the picture go away after watching for a certain period? Does it come back after a certain time? Do you have to cycle power or let tv sit for pic to return? Is it repeatitive? Also, when you say you still have audio, do you actually have audio of the program that was on, or just sound (frying) coming from the speakers? The issue you are experiencing is very different from what I had. I went to turn the tv on one day and there was no pic, and I did not have failures prior. So as...Last edited by damiane; 07-18-2013, 12:20 PM.Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
RESOLUTION:
I received the new buffers in and installed them with the same results. After SMH for a while I finally called up the folks at tvrepairguy.com where I got the parts from. They were gracious enought and offered to test all my boards, so yes I cheated a bit. I sent them all the boards from my set (except the PS board) and they would install them in the same tv that was on their test stand.
What the found was that the control board worked, main board worked, Z-SUS worked. New buffers worked, but old buffers and both...Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
Been away for a while, but wanted to thank everyone again for their input. After all the troubleshooting and data gathering, I went ahead and ordered replacement buffer (y-drive) boards that should be delivered today. I will perform tests on the new board before installing to compare the results to the existing. This will mean new buffers and Y-SUS so I am keeping my fingures crossed. Will let you know the results.Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
Seems like ai had attachnment issue also...let's try again in .pdf....Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
Some really good in for here. PK7... I did not see your page 69 attachment, however, I did perform the buffer test (see attached .doc) a few days ago.The only part that I was not able to do was with the unit running as there is no Vy and Vsc to send voltage to that area. I indicated in "red"the abnormalities.
Not to throw another monkey wrench in the system, but for grins I was checking PS voly=tages and in standby the voltage across the main fuse should be 123V and 382V when unit is running. However I only read 325...Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
Attached is the section from the manual I followed and still got no image, but the LED flashed as it should and the voltages checked out. There is a section for attaching a scope, but I did not got that far as I would have to barrow a scope, plus the tests I performed seemed to pan out.
(Hopefully the attachment works)...Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
Tom66, Thanks for the response, that's good to know about the input selection and pressing ok, I will try that later this week when I am back in town. As for the Y-SUS and the Vy and Vsc issue, when I first took the unit apart the main fuse on the Y-SUS was blown. Replaced the fuse and the TV would power off after a few seconds. Repaced the Y-SUS and at least it powers on now. As I mentioned the Y-SUS is a refurb, so I can't guarantee it works 100%, but the TV store I got it from said it tested good. I can try another Y-SUS, but as this one...Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
Thanks Capkid. I get sound but not associated with the input...regardless of where I stop when selecting the input button, I get the "frying" sound like when you or on air on untuned channel. Per the original post, I would expect a different result like no sound when I get to an input like a hdmi....of course I can't see if the input is changing with no pic. Hope this makes sense.Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
Thanks for the response pk7... I performed the action as I suspected no changes with either or both buffer boards out, no image and the -Vy and Vsc still do not read. I still think there could be an issue with the buffer boards, but will need conclusive evidence. If I can get the question answered regarding these voltages, this may clear a few things up for me.
Purpose of Vy and Vsc as defined by the LG repair manual;
-VY VR502 - -VY Sets the Negative excursion of the Y-SUS Drive Waveform
VSC VR501 -VSC Set the...Leave a comment:
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Re: LG 50PQ30C-UA No picture - blank PDP
From reviewing the responses to other posts, I went through the process of powering up the unit with one Y-Buffer (Drive) board at a time, then with neither connected, still no images. The process I used for this was to disconnect the ribbon cables going from the buffer board to the PDP, so the board was still connected to the Y-SUS, is this acceptable? As I am typing this I am thinking maybe I want to power up with one board at a time totally removed from the unit. Don't think it will make a difference, but will try. Any thoughts?Leave a comment:
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LG 50PQ30C-UA No picture - blank PDP
LG 50PQ30C-UA Troubleshooting steps:
Screen was not powering up.
Upon turning on the red LED goes to BLUE and stays there, meaning the system was on (sending out voltage). The display would however be blank (no light at all).
With Power supplied:
Checked all voltages on PS board (input and output). The following voltages were in line
Vs = 193V
Va = 60V
and all +5V terminals read as they should.
Voltages read correct at the connection points on X and Y Sustain boards also.
Looked at Caps and all caps on all boards... -
Re: New Members - please post your introductions here
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