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Old 08-27-2019, 03:49 PM   #1
MerlijnD
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Default Lg 60pz570 No picture, No sound, No Z-Y voltages

Hi people,

Got my hands on a sweet 60 inch plasma. Guy i bought it from showed me live at his house: Turn on, relay clicks, faint glow until you turn it off.

So I went online, searched and found around the same model and people saying cracked solder etc, fused. So I wasn't smart and just took the boards apart as im a "electronics hobbyist". Indeed 1 or 2 cracked solder points. Fets measured OK from a quick check on my end, so did the fuses.

Resoldered the points, replaced one "starting to bulge" capacitor, and put the things back in. But now it does nothing anymore. As in: Turn on, relay clicks but no faint glow anymore. Just black screen.

Baseline:

Zsus
Incoming:
All in spec

Outgoing:
VZB: 0.9v

Ysus
Incoming:
All in spec

Outgoing:
VY: 0v
VSC: 0v

=============================================
When disconnecting Ysus board power ZSUS VZB 0V.
When disconnecting ZSUS board power Ysus both test points still 0v.

Led on logic board blinks Long-Long-Short-Pause-Short
Not quite sure how sensitive these boards are, but incoming 5v = 5.16v. Not sure if thats within spec.

=============================================

Disconnecting LVDS and jumping ext_auto_gen:

Zsus
Incoming:
All in spec

Outgoing:
VZB: 5-9V

Ysus
Incoming:
All in spec

Outgoing:
VY: 5V
VSC: 5V

Nothing on screen. Faint coilwhine from ZSUS board, double powercycle on ZSUS board (10 seconds in between, 2 seconds slight coil whine per cycle), Tv turns off after that.

I have literally no idea what's wrong, yes it was stupid to not test the voltages when it still had the dim glow, but instead i fixed the solder cracks first. Anybody know whats going on?

Greetings,
Merlijn

Last edited by MerlijnD; 08-27-2019 at 03:58 PM..
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Old 08-27-2019, 04:14 PM   #2
R_J
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Default Re: Lg 60pz570 No picture, No sound, No Z-Y voltages

Start by rechecking every connection you soldered, you may have shorted a couple connections together. Post some pictures of the y-sus and otherboards you worked on.
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Old 08-30-2019, 02:32 PM   #3
MerlijnD
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Default Re: Lg 60pz570 No picture, No sound, No Z-Y voltages

Hi, I've rechecked everything and i am 100% certain all is good. No solder blobs, in EXT-AUTO_GEN mode it sounds like the ZSUS board wants to start (9V coming out) or something but the YSUS board seems completely dead (2V coming out).

All of the SMPS voltages are bang on (except the 5v (5.16v)) with the label on the back.
Reseated connects, and measured buffer boards. Found no direct shorts to ground.

Pictures attached.
Attached Images
File Type: jpg IMG_20190830_222729.jpg (582.3 KB, 4 views)
File Type: jpg IMG_20190830_222734.jpg (660.4 KB, 3 views)
File Type: jpg IMG_20190830_222737.jpg (711.9 KB, 4 views)
File Type: jpg IMG_20190830_222741.jpg (471.6 KB, 3 views)
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Old 09-02-2019, 04:19 AM   #4
MerlijnD
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Default Re: Lg 60pz570 No picture, No sound, No Z-Y voltages

Quote:
Originally Posted by R_J View Post
Start by rechecking every connection you soldered, you may have shorted a couple connections together. Post some pictures of the y-sus and otherboards you worked on.
Small update, I mucked around with my hairdryer. Warmed up the ZSUS and Control board. Behavior changes a bit, relais in SMPS got a bit spastic and i got 55V on the ZSUS board for a brief moment.

18v control is present on YSUS board 1-2 seconds after startup. Then its gone again (so is the static noise/coil whine).
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Old 09-11-2019, 01:15 PM   #5
MerlijnD
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Default Re: Lg 60pz570 No picture, No sound, No Z-Y voltages

Well it wasnt the logic board, replaced that. Same issue, same blinks.
Disconnecting 1 or the other buffer board didn't make any difference.
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Old 09-12-2019, 01:52 PM   #6
MerlijnD
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Default Re: Lg 60pz570 No picture, No sound, No Z-Y voltages

Well I measured the 18v control signal on the ZSUS board, measurus 4.5v.
The 15v outgoing rails from the YSUS (guess this is boosted to 18v normally?) is dead, same 4,5v.

Now I don't know when these voltages should be there, if they should be there during startup or if they are controlled by the logic board.

From reading other threads regarding the missing 18v, i've seen people talk about the voltage regulator, sadly this is on the back of the board for me, so I can't measure it while on.

Does anyone know if it's worth it to blindly replace the 200D6 pwm switching controller IC, or am I looking at the wrong IC here?
Looked at this thread: https://www.badcaps.net/forum/showpo...9&postcount=18
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