Hi Kim,
The sound could be come from the internal sparking of the flyback transformer. As for the brightness control, tracing bad components along the brightness control line may be able to locate the fault. It can be an open resistors, circuit track broken and etc. Without hands on assessment on this TV, it would be difficult for me to tell what is the exact problem.

Jestine

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hello,sir Waleed.
I have LG slim TV(21fu1r-ns of 220 voltage) and It has also the same problem(lines across screen) whenever the screen is completely black.
But It also possible to see the actual picture.

I adjust screen potentiometer on the flyback transformer,But It was impossible to get rid of these lines across screen problem.

The below links is a schematic of MC059C PCB,and It seems that most of crucial components is the same to 21fu1r-ns.

https://i.imgur.com/kkLKfZN.jpeg

Following your tutorial,I want to resolder all pin of ocilator Ic in order to solve this problem(lines across screen),But I cannot locate a component, which is ocilator IC, from MC059C schematic.

I really appreciated if you would let me know which components is real ocilator IC from MC059C schematic.

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I have LG slim CRT TV(21fu1r-ns of 220 voltage) which was not able to display any screen.So I did IN CIRCUIT Testing all of capacitor with MESR-100 ESR meter. I found a capacitor which has no ESR and capacitance value at all, It was connected to horizontal coil(C420 250v 1uf). So I replaced this capacitor and other capacitor which is located in the vicinty of FBT(C540 250v 4.7uf) and in the vicinty of Vertical Deflection Booster(STV9326)(C307 35V 100uf) which has somewhat higher ESR value,So I also replaced these capacitor,too.

Below picture is MC059C schematic. It seems that most crucial components is the same with 21fu1r-ns PCB which I try to repiar.

https://i.redd.it/m0b68t9i9drc1.jpg

After replacing three capacitor,It finally succeeded to display a screen,But,the screen was very bright and It displayed lines across the screen like your article. Worst of all, IT IS NOT ABLE TO CONTROL BRIGHTNESS with screen adjust potentiometer on the lower FBT...

Besides I heard a weird static sound near CRT anode cap whenever I turn off this 21fu1r-ns CRT TV like below video.(You can hear static sound from 00:52 to 01:05)

https://www.dropbox.com/scl/fi/36xkcljhnoyw9ffnj8ow1/20240531_150631.mp4?rlkey=e7a51f4ak7p2m9gvuikgfjcx2&st=8ttjyzxy&dl=0

I really want to control brightness with screen adjust potentiometer on the lower FBT and get rid of weird static sound.

I really very much appreciate you if there is workaround to repair this problem and if there is any tutorial to measure G1 voltage.

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Hi Habtamu,

Dim display can be caused by weak picture tube, low g2 voltage and even low heater voltage.

Jestine

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yours Student
Amir Mukhtar

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Yeah!!!! I think it went through!! 🙂

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HI Robert,

My email is jestineyong@electronicrepairguide.com. You can try resend.

Jetsine

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Hello Mr. Yong. I wrote the article and added some pictures and sent the email but I'm not sure it went through. One of them said your name was not recognized or something like that. If it didn't go through I'll have to find out what is going wrong.

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