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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

11-07-2014, 02:14 AM
Re: LG 47LV550W audio and back light works / no picture

Yeah my thoughts exactly. I ordered one from eBay for 35$. So for my part I can recommend [URL="http://www.ebay.com/usr/coolyouparts?_trksid=p2047675.l2559"]seller coolyouparts[/URL]. Quite fast for free delivery (10 days from order) and packaging was great.

So this time I got lucky and got working set for 90 bucks, few hours of troubleshooting and ofcourse your priceless help. Re: LG 47LV550W audio and back light works / no picture

Yeah my thoughts exactly. I ordered one from eBay

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

11-06-2014, 01:11 PM
Re: LG 47LV550W audio and back light works / no picture

Just wanted to report that new TCON board solved the problem. Thank you all who helped on the way, specially warm thanks to Budm!

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-20-2014, 06:00 AM
Re: LG 47LV550W audio and back light works / no picture

Any comment on these voltages?

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-16-2014, 11:54 AM
Re: LG 47LV550W audio and back light works / no picture

I tried VGH when removing both ribbon cables:10,66v
Only one connected: 6,53v

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-16-2014, 11:13 AM
Re: LG 47LV550W audio and back light works / no picture

From what I have read in these forums it seems that problem might be low VGH voltage. Apparently it should be atleast same as VDD?

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-16-2014, 01:33 AM
Re: LG 47LV550W audio and back light works / no picture

Thanks for the tip, is there something special to note while taking it apart? Or better yet a step-to-step tutorial so not to do any damage?

Budm mentioned that Vgh, Vgl, Vst_in dont look normal. What would be normal voltages for those?

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-15-2014, 01:32 PM
Re: LG 47LV550W audio and back light works / no picture

Here's another video where you might see abit better; [URL="http://1drv.ms/1sQE7DO"]http://1drv.ms/1sQE7DO[/URL]Re: LG 47LV550W audio and back light works / no picture

Here's another video where you might see abit better; [URL="http://1drv.ms/1sQE7DO"]http://1drv.ms/1sQE7DO[/URL]

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-15-2014, 01:18 PM
Re: LG 47LV550W audio and back light works / no picture

Here's a short video with no input plugged in: [URL="http://1drv.ms/1tu9SDP"]http://1drv.ms/1tu9SDP[/URL] , I think there's some kind of "screen saver"/no input detected type of thing moving.

Also plugged computer to it and playing video makes lines move and shift the, seems like depending on how much contrast difference there is (you cant really see it properly in the video): [URL="http://1drv.ms/1sQAI88"]http://1drv.ms/1sQAI88[/URL]Re: LG 47LV550W audio and back light works / no

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-15-2014, 11:58 AM
Re: LG 47LV550W audio and back light works / no picture

Below readings are with no input:

GMA1: 14,43v
GMA3: 14,32v
GMA4: 13,58v
GMA5: 12,50v
GMA7: 10,57v
GMA9: 8,60v
GMA10: 7,93v
GMA12: 6,21v
GMA14: 4,24v
GMA15: 3,17v
GMA18: 2,45v

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-15-2014, 01:18 AM
Re: LG 47LV550W audio and back light works / no picture

They were as you say decreasing from right to left. So does this indicate that the problem is not the TCON? I'll take a video after work but those lines change on screen when there's varying picture source.

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-14-2014, 02:03 PM
Re: LG 47LV550W audio and back light works / no picture

Yeah I measured them and they are the test points GMA1...7: Varying 14,4v-10,5v
GMA9...18: Varying 8,6v-1,1v

This was with IPTV hooked. Will check without signal at some point.

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-14-2014, 10:58 AM
Re: LG 47LV550W audio and back light works / no picture

Thanks alot for your help, couldn't have made it this far without you.

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-14-2014, 10:42 AM
Re: LG 47LV550W audio and back light works / no picture

Ok transistor is now changed and voila voltages are now normal, 11,9v at TCON fuse when TV on and 0v when off. But. Picture is as you can see. First one both ribbon cables plugged and others only one.

Measured following volts at TCON, normal TV show on HDMI1:

P_VDD: 16,57v
GMA1...7: Varying 14,4v-10,5v
GMA9...18: Varying 8,6v-1,1v
VCC: 3,29v
VDD: 16,68v
VGL: -4,94v
UC1: 0v
VGH: 4,66v
VST: -4,93v
VGH_EVEN: Varying -5v-5v
VGH_F:...

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-14-2014, 04:53 AM
Re: LG 47LV550W audio and back light works / no picture

On a side note, I have easy access to this part:
Would it be suitable for testing the board?

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-14-2014, 12:22 AM
Re: LG 47LV550W audio and back light works / no picture

Will do after work, thanks.

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-13-2014, 10:44 PM
Re: LG 47LV550W audio and back light works / no picture

S-D: 101ohms
S-G: 120ohms
D-G: 20ohms

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-13-2014, 06:44 PM
Re: LG 47LV550W audio and back light works / no picture

Yeah marked values in picture.

Top right: TV ON 12.03v/11.98v TV OFF
Bottom right: TV ON 9.58v/9.91v TV OFF
Middle left: TV ON 9.67v/9.91v TV OFF...

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-13-2014, 06:03 PM
Re: LG 47LV550W audio and back light works / no picture

Apparently it is this one if I read the schematics of SM right: [url]https://cdn.badcaps-static.com/pdfs/3827879fa171807285bfa8fa1ec3aa2d.pdf[/url]Re: LG 47LV550W audio and back light...aa2d.pdf[/url]...

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Last edited by Masba; 10-13-2014, 06:10 PM. Reason: Added panel power schematics
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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-13-2014, 04:53 PM
Re: LG 47LV550W audio and back light works / no picture

Part # Q507 gives 0,8 ohms. Marked in the picture. There are markings X72A and 21 on the part....

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Masba replied to LG 47LV550W audio and back light works / no picture

in Troubleshooting TVs and Video Sources

10-13-2014, 04:33 PM
Re: LG 47LV550W audio and back light works / no picture

They connect to pins 48-51, marked with red circle. Tried measuring those four pins and got same results from all as from the fuse. That is 9,72v TV on, 9,9v TV off and 10,2v ribbon cables in TCON detached....

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Last edited by Masba; 10-13-2014, 04:35 PM.
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