Re: LG 60PV400 - Power but no picture
An upper Y buffer fixed the tv. My only worry is that the YSUS caused the buffer to short. I'll update this thread if anything happens but so far so good.
Thanks everyone.
97Kouki
Member
Last Activity: 07-05-2021, 01:28 PM
Joined: 05-26-2016
Location: Pearl, MS
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Re: LG 60PV400 - Power but no picture
Servicemanuals.proLeave a comment:
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Re: LG 60PV400 - Power but no picture
Pins 1 and 2 are Va and they are shorting to ground through the buffer, not Vsc.Leave a comment:
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Re: LG 60PV400 - Power but no picture
Ok, I'm pretty sure I have it solved now. I had removed a couple transistors from the YSUS board because they were showing open in circuit. Once I got them out and tested them I got a reading so I soldered them back in. While I was at it I touched up some very slightly questionable points and all of the other transistors. That is when I put it back together and found that the lower buffer connector on the YSUS board had VSC but not the VSC points.
Turns out that the lower buffer is what transfers VSC from that point to the VSC points....Last edited by 97Kouki; 05-27-2016, 11:13 PM.Leave a comment:
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Re: LG 60PV400 - Power but no picture
Update: I'm determined not to give up on this board. About 2 inches from the vsc points there is a plug that goes into the lower buffer. Pins 9 and 10 say they are supposed to have vsc voltage... And they read 150v. But not the vsc points. I'm going to examine the traces and see why the vsc points aren't showing voltage but the circuitry is obviously working to produce the voltage....Leave a comment:
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Re: LG 60PV400 - Power but no picture
I didn't find any diodes on the board and all transistors measured uniform with no shorts. Weird. Is there any way to easily test the buffers so I can be sure i don't need to replace them?
I don't know if this matters but the whistling sound the YSUS board was making disappears when either the buffer boards are completely removed or the ribbon from the control board is removed.Last edited by 97Kouki; 05-27-2016, 06:18 PM.Leave a comment:
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Re: LG 60PV400 - Power but no picture
I measured the only three I could find, fs101, fs102 and fs103. All show good. Would this board be worth attempting repair? While poking around I found that resistor r309 is shorted, reading .002 ohms from one leg to the other....Leave a comment:
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Re: LG 60PV400 - Power but no picture
Thanks so much for your help. I went and bought a Fluke DMM to make sure I'm getting correct readings. Below is what I found.
M5v: 5.17v
Vs: 202v
Va: 55v
VZB: 110v
VSC: 0v
Again, thank you.
Edit: I just completely removed both Y buffer boards from the TV and measured VSC again. No change, VSC is still reading 0v. Am I correct in assuming the problem is isolated to the Ysus board? Where do I go from here?...Last edited by 97Kouki; 05-27-2016, 04:57 PM.Leave a comment:
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Re: LG 60PV400 - Power but no picture
I just noticed you mentioned VE as well. I don't see a sticker with VE on it. Only M5v which is supposed to be 5v but I read about 5.5v.Leave a comment:
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Re: LG 60PV400 - Power but no picture
I did. The voltages are Va:55v and Vs:201v. I checked the voltages on the power board and where they connect to both sustain boards, power is getting to both boards. It may be my multimeter but I read Va:59v and VS:218v. I may go purchase another DMM just to make sure. I'm thinking about trying the pattern jumper but I'm not sure that would help as the panel doesn't power on at all. Would the pattern test power on the panel in a situation like this?Last edited by 97Kouki; 05-27-2016, 10:22 AM.Leave a comment:
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Re: LG 60PV400 - Power but no picture
Just an update, I purchased the service manual for this model. I'm going through it now to see about diagnostic steps.Leave a comment:
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Re: Samsung LNT4669FX/XAA random horizontal line and restart issues
I agree with the original assessment. The horizontal lines you mentioned sound like bonding tab issues. I have a HannsG monitor that shows the same symptoms. There is no fix.
Bonding tab issues and symptoms change with the heat of the panel. When mine is cold almost half the screen is covered in horizontal lines. After an hour or so only a handful remain. Leave it on a couple days and the display is perfect. It sounds like yours is shorting out though.Leave a comment:
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Re: Samsung BN44-00445A failed
It does but a continuity test between QP804 and each side of it should determine if my eyes are playing tricks, but it looks burnt and separated. Fixable in any case though.Leave a comment:
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Re: Samsung BN44-00445A failed
Upon further inspection DP804 looks like the adjacent legs are bridged.Leave a comment:
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Re: Samsung BN44-00445A failed
It looks as though the through-hole solder sleeve has pulled away from the trace on QP804. I would at least do a continuity test on the Pin in QP804 to the bottom left leg of DP802. If continuity exists then the connection would be OK on this side of the board even though it looks ugly. But just looking at it makes me think it's no longer connected to the trace.Leave a comment:
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LG 60PV400 - Power but no picture
I have a 4 year old LG plasma 60PV400 that was working fine up until 4 months ago. I started having the green and pink snow on the display. A search on BadCaps.net told me to reflow the inductors on the YSUS and ZSUS boards. That fixed the colored snow and the TV worked fine for another 4 months.
Yesterday, my wife turned the TV on and after about 5 minutes of watching it she said the screen went dark. No POP, sizzle, smell or anything. The TV remained on, responded to the remote, and behaved normally except the plasma panel was off.
I tried the flashlight test and... -
Re: New Members - please post your introductions here
Hi, my name is Chris and I have been repairing electronics as a hobby for 14 years. I started with video game consoles at the age of 16 and I am now doing my best to branch out to other devices. I am usually just replacing parts but would like to learn more about component-level repair. I have occasionally visited this website because the vast wealth of knowledge on devices I have repaired but I am happy to finally be part of the community.Leave a comment:
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