LG CRT TV turns off after few seconds + White horizontal lines


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LG CRT TV turns off after few seconds + White horizontal lines

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madhushankarox
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Nov 17, 2013, 2:27 PM

Post #1 of 36 (8638 views)
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LG CRT TV turns off after few seconds + White horizontal lines	Can't Post

I'm trying to repair a LG CRT TV witch turns off (standby mode) withing few seconds after starting. Wired thing is this happens only if I have inputted video signals trough A/V inputs or if I have plugged in my antenna cable. Menu is visible and working fine without going to standby mode. Default blue screen also working fine.

Additionally pictures are very dark and cannot see anything until I august the G2 control (Menu and the default blue screen is visible without adjusting G2). But this cause horizontal lines and a big vertical faded line to be appear like following image.

Please help me to find the issue for this. Thanks!

(This post was edited by madhushankarox on Nov 17, 2013, 2:32 PM)

jts1957
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Nov 17, 2013, 9:08 PM

Post #2 of 36 (8610 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Crystal ball not working today - therefore I can't make out unit's identifying numerals. Smile

White horizontal lines were caused by you turning up G2 - turning this back down will eliminate them.

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Location: Far, Far Away

(This post was edited by jts1957 on Nov 17, 2013, 9:11 PM)

madhushankarox
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Nov 18, 2013, 1:59 AM

Post #3 of 36 (8603 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Ya.. Turning G2 down is working. But the issue is I cannot see any image (except menu and the blue screen if there is no video input) after this. Still turns off the TV after few seconds.

jts1957
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Nov 18, 2013, 2:23 AM

Post #4 of 36 (8601 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Attempt #2:
Crystal ball not working today - therefore I can't make out unit's identifying numerals. Mad

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Location: Far, Far Away

madhushankarox
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Nov 18, 2013, 2:42 AM

Post #5 of 36 (8599 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Sorry.. This is LG CF-14K40KE

BTW what happened to your crystal ball? he he :)

jts1957
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Nov 18, 2013, 3:26 AM

Post #6 of 36 (8596 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

HAS audio & video signal thru A/V jacks - at least until set turns off?
HAS audio & video signal thru tuner - at least until set turns off?

It broke. The polish maker forgot to tell me that the crystal ball will be hard to hold once the polish was spread onto it. Unsure

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Location: Far, Far Away

(This post was edited by jts1957 on Nov 18, 2013, 3:38 AM)

madhushankarox
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Nov 18, 2013, 6:26 AM

Post #7 of 36 (8590 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Hmm YA.. It's going to standby mode after inputting a signal. If I pressed the channel or turn it on again, it's working only for few seconds and going back to standby. power LED is static.

he he Crazy

jts1957
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Nov 18, 2013, 7:07 AM

Post #8 of 36 (8585 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Attempt #2:

HAS audio & video signal thru A/V jacks - at least until set turns off?
HAS audio & video signal thru tuner - at least until set turns off?

If one were to inject a 'test pattern' along with a 'test tone' thru the A/V input jacks, would one observe a 'test pattern' on the CRT screen and a 'test tone' out of the speaker for these 'few seconds'? ("it's working only for few seconds and going back to standby")
If one were to tune into an 'over-the-air' broadcast of ____ (insert name of your favorite TV show), would one see the picture of this TV show on the CRT and hear the sound of this TV show from the speaker for these 'few seconds'? ("it's working only for few seconds and going back to standby")

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Location: Far, Far Away

madhushankarox
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Nov 18, 2013, 1:35 PM

Post #9 of 36 (8578 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

1. Yes. It is working for few seconds and going to standby
2. Yes. Same

What ever video or audio I input, I can see it and hear the sound of it.
I've re-soldered vertical section and now got a screen like following image. I don't know what the heck has happened :( . I can hear the sound and with this screen also it's going to sleep.

* I've desoldered the vertical IC and tried. Got the bright horizontal line, sound and went to standby like before (Takes more time to go to standby).

madhushankarox
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Nov 18, 2013, 3:15 PM

Post #10 of 36 (8573 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Can you recognize following resistor? Is it 8.25 MEG ohms or 54.5 K ohms

jts1957
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Nov 18, 2013, 3:48 PM

Post #11 of 36 (8564 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

What does it measure? What is its location number? Remember, my ball is broken. Wink

Which 'standard' test pattern is that supposed to be? Crosshatch? LGBT Color Bars? Indian Head?

Microprocessors usually require a 'sample' of both vertical and horizontal drive to position/synchronize the OSD and allow the set to stay 'on.' Try swapping out the LA7840 (IC301).

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Location: Far, Far Away

(This post was edited by jts1957 on Nov 18, 2013, 4:01 PM)

madhushankarox
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Nov 18, 2013, 4:09 PM

Post #12 of 36 (8556 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

lol I was stupid Sly

. It is R812 (Closer to regulator). That was not a test pattern Crazy

. This is how I see blank screen with white dots (The image I posted in my question) and all of the videos. Menu also not working Unsure

madhushankarox
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Nov 18, 2013, 4:21 PM

Post #13 of 36 (8550 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

I've already swapped the IC. No luck.

How to edit posts without messing them up?

jts1957
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Nov 18, 2013, 4:51 PM

Post #14 of 36 (8540 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

R812 Part # 0RK8204H609 Desc. 8.2M OHM 1/2 W 5.00% TA52
When I edit using Firefox browser I get as you call it all messed up. When I edit using Opera browser works like it should.

Example:
R812 Part # 0RK8204H609 Desc. 8.2M OHM 1/2 W 5.00% TA52 <br> <br> <br>When I edit using Firefox browser I get as you call it all messed up. When I edit using Opera browser works like it should. <br>

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Location: Far, Far Away

(This post was edited by jts1957 on Nov 18, 2013, 4:55 PM)

madhushankarox
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Nov 18, 2013, 4:54 PM

Post #15 of 36 (8535 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Hmm seems like not the resistor.. Frown

Thanks for the tip Smile

jts1957
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Nov 18, 2013, 4:57 PM

Post #16 of 36 (8534 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Can you post a picture of your CRT screen showing a standard test pattern?

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Location: Far, Far Away

madhushankarox
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Nov 19, 2013, 2:07 AM

Post #17 of 36 (8521 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Sorry! I cannot see anything other than this

Sound is working. Seems like re-soldering might have done something.

(I found a way to edit post without messing after publishing. Select HTML as Post Style. I'm okay with HTML Wink

coz I'm a web developer Crazy

)

(This post was edited by madhushankarox on Nov 19, 2013, 2:29 AM)

jts1957
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Nov 19, 2013, 3:02 AM

Post #18 of 36 (8512 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Get a strong magnifier and find out what you've bridged, floated or splashed while soldering. Mad

Turn down G2.

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Location: Far, Far Away

madhushankarox
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Nov 19, 2013, 7:43 AM

Post #19 of 36 (8509 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Hmm.. I have checked but nothing found Unsure

. When I got this TV, It was not showing any image. Flyback suction cup was leaking and replaced. Flyback neck was also leaking and I've sealed with some glue (hard like plastic) and not leaking now. There was no color or any image other than the menu. replaced the color IC, TDA6107 and It worked. Now I'm stuck Unsure

madhushankarox
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Nov 19, 2013, 8:49 AM

Post #20 of 36 (8507 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Can you please tell me the value of C905 (Close to color IC) I have a resistor their Crazy

jts1957
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Nov 19, 2013, 10:41 AM

Post #21 of 36 (8501 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Quote

There was no color or any image other than the menu. replaced the color IC, TDA6107 and It worked.

WHAT worked?
Set has NEVER had a recognizable video picture from ANY source (other than menu - at one point earlier)?

IC901 DC voltages (don't have to be exact, but within +/- 20%) pins 1 thru 9= 2.43; 2.35; 2.35; 0; 6.5; 188.4; 140; 147 & 147 (reference ALL to pin 4 Gnd).

*******************************************************

Are ALL power supplies within specifications?

C905 Part # 0CN5610K519 Desc. 560P 50V K B TA52

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Location: Far, Far Away

(This post was edited by jts1957 on Nov 19, 2013, 10:45 AM)

madhushankarox
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Nov 19, 2013, 1:49 PM

Post #22 of 36 (8498 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

When I start to repair this, There were no any image on the screen. 1st I've fixed the flyback suction cup and some leaks. I got only menu after that. Next I swapped the IC, TDA6107 and got pictures.

I was able to fix the white screen issue. It was a dry solder joint I guess. I've re-soldered some joints and I got the menu and the screen back.

Turned down the G2 and got a darker screen (See attached). Tried to increase color setting with the menu and it's not working. Channel tuning and volume is working fine. But the setting for the color, brightness is not working Frown

This unit has a 560ohm resistor as C905

I will check voltages and update you.

Thanks so much!

jts1957
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Nov 19, 2013, 2:18 PM

Post #23 of 36 (8494 views)
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Re: [madhushankarox] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Quote

But the setting for the color, brightness is not working

I2C controlled. Possibly corrupt EEPROM (IC03)?

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Location: Far, Far Away

madhushankarox
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Nov 19, 2013, 2:25 PM

Post #24 of 36 (8492 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

Do I have to re-program that? (Is there a way to reset?)

* Channels number is increasing while I'm decreasing. But sometimes

(This post was edited by madhushankarox on Nov 19, 2013, 2:32 PM)

madhushankarox
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Nov 19, 2013, 4:56 PM

Post #25 of 36 (8475 views)
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Re: [jts1957] LG CRT TV turns off after few seconds + White horizontal lines [In reply to]	Can't Post

I've replaced C905, 560ohm resistor with a 560p capacitor and it took some time (actually like 2 MINUTES) to go to standby mode (But only few times then again it started to go to standby mode like before). When I'm tuning G2, I got a very good picture for a second and disappeared. See my YouTube video

Voltages:

Here is the blue screen While I was measuring voltages (Ignore lines. That's my cam. I got a solid blue screen (Left top was reddish). not solid blue then lol)

(This post was edited by madhushankarox on Nov 19, 2013, 4:59 PM)

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