LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old)


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LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old)

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linkin93
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Feb 23, 2010, 11:25 AM

Post #1 of 8 (5641 views)
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LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old)	Can't Post

Hi, this is my first post here. Straight to the problem: We bought a non-functioning plasma for $105 off of eBay <img src="http://www.tv-forums.com/images/cool.gif" alt="Cool" border="0"> <br> <br>The problem is that the screen flashes colours twice per second, mainly when the screen has bright colours. when darker colours are present, the flashing is almost unnoticable. <br> <br>Now, my dad is an electrician, and we bought the TV hoping to fix it. We have opened up the back of the TV, and according to google: <br> <br><span contenteditable="false"><table border=0 cellpadding=0 cellspacing=0 width="100%"><tr><td width="2%"><hr width="100%" noshade size="1" color="#A1A576"></td><td width="6%" align=center><font size=1 face="Verdana,Arial,Helvetica">Quote</font></td><td width="92%"><hr width="100%" noshade color="#A1A576" size=1></td></tr></table></span><div style="margin-left: 30px">I also had this problem with my LG 42" plasma. <br>Many Plasma tv:s have LG YSUS boards. I changed C72 on my ysus board 6871QYH029A and it fixed the flashing problem. But I still have some sparkling pixels that I need to get fixed.</div><span contenteditable="false"><table border=0 cellpadding=0 cellspacing=0 width="100%"><tr><td><hr width="100%" noshade size=1 color="#A1A576"></td></tr></table></span> <br>The pixel thing is a non-issue. it isn't our problem, but the flashing is. the YSUS board in our TV is labelled as <b>6871QYH027A</b> which seems to be the first revision. We intend to find and replace the C72 capacitor as the person above did. But we can't find it. <br> <br>If anyone knows where this C72 capacitor is or you have a circuit diagram of that YSUS board, it would a great help. Thanks for your time. <img src="http://www.tv-forums.com/images/smile.gif" alt="Smile" border="0"> <br>

EDIT: Okay, we have found the capacitor, it was hiding in plain sight Unimpressed

I'll let you know how replacing that capaictor goes.

(This post was edited by linkin93 on Feb 23, 2010, 11:55 AM)

techchris
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Feb 23, 2010, 4:22 PM

Post #2 of 8 (5630 views)
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Re: [linkin93] LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old) [In reply to]	Can't Post

check the sustain voltage is correct as per the label on the back of the screen. I am truly amazed an LG is still working after 7 years, most bite the dust after 3-4.

linkin93
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Feb 23, 2010, 10:09 PM

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Re: [techchris] LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old) [In reply to]	Can't Post

Well, the manufacture date is Jul 1/2003, so technecially it might only be 5-6 years old. Anyway, me and my dad someone with the same problem on another forum, only it was in french, but thank you google translate; we know exactly what to do now. here is a pic of what we need to check and/or replace:

http://img23.xooimage.com/.../0/y-sus-12a2bf8.jpg

But yeah, it has to do with an ocsillating voltage. we need to replace some IC's (i think they are actually optocouplings) and some capacitors.

The other guy replaced: VR4, IC21, IC3, IC8, C59, C38, C34, C40, C46, C41. Not all of them were dead, but something he replaced on the YSUS board got it working again.

(This post was edited by linkin93 on Feb 23, 2010, 10:13 PM)

Ron.M
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Feb 24, 2010, 12:12 AM

Post #4 of 8 (5622 views)
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Re: [linkin93] LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old) [In reply to]	Can't Post

linkin93;.....

FYI;....Link no good !!!

http://img23.xooimage.com/.../0/y-sus-12a2bf8.jpg

Later....Ron.M.... Cool

.....
Veteran & Retired TV technician

linkin93
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Feb 24, 2010, 1:05 PM

Post #5 of 8 (5617 views)
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Re: [Ron.M] LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old) [In reply to]	Can't Post

hmm... you're right.

lets try again:

http://img23.xooimage.com/.../0/y-sus-12a2bf8.jpg

Anyway, we pulled the YSUS board out, tested those caps and didn't find any shorts.

Anyway we are going to find matching caps for all of the ones i listed before (my dad works at Jaycar so it's really handy!) and replace them.

I'll let you know how it goes. has anyone ever had experience with this TV? Apparently it's used in many plasmas. the # is PDP42V50000

linkin93
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Feb 25, 2010, 12:42 PM

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Re: [linkin93] LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old) [In reply to]	Can't Post

We replaced 2 capacitors (C38 and another one i cant remember right now) and no luck. however, before there was a pulsating noise coming from a transformer. now it's gone after replacing the caps.

We have more caps to change but it's late.

linkin93
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Feb 26, 2010, 12:16 PM

Post #7 of 8 (5599 views)
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Re: [linkin93] LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old) [In reply to]	Can't Post

No dice with those 5 capacitors. still flashig. has anyone got any advice?

linkin93
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May 24, 2010, 7:47 AM

Post #8 of 8 (5415 views)
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Re: [linkin93] LG RT-42PZ45V 42" Plasma Problem. (TV is 7 years old) [In reply to]	Can't Post

Okay, bump!

We ended up replacing a total of 6 capaictors. they didn't do anything. Next, we replaced IC21, VR4, IC3 and IC8. Before we got a chance to test that out, my dad insisted on testing the other circuit with his multimeter. as he was saying "i shouldn't do this because it might short" - it shorted. Unimpressed

Now the TV has no picture at all. He fried one of the Power Control Switch IC's like the one we replaced. He has two of them so we can fix it.

But, the TV still turns on and the light is green, sound is still there but there is no picture whatsoever now. this leads us to believe that there is no power being given to the screen itself. I think it gets 190 volts or 220 volts, can anyone help us with this?

thanks in advance!

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