User Profile

tmhobadcap started a topic TCL 65S403 Backlight LED Question

in Troubleshooting TVs and Video Sources

05-25-2025, 11:03 AM
TCL 65S403 Backlight LED Question

I got the TV from a friend. He claims that no image but sound from the TV.
I confirmed that when shine a flashlight on to the screen, I can see the image. And this should be backlight problem.
I open up the TV and found a few leds failed. And now I am ordering a new set of backlight strips for it.

But there is something that I do not understand when checking the leds. I do not have an led tester. I only use a bench power supply. I first set the voltage to 3V and current to 10mA. I could not light up the led until I increase the voltage to 12V. I understand most...

See more | Go to post
tmhobadcap replied to TCL 65S403 Blank Backlit Screen w/ sound ... voltage besides 12v missing at LVDS

in Troubleshooting TVs and Video Sources

05-25-2025, 10:10 AM
Have you tried checking on the backlight leds?
I have the same tv with a few leds failed. Then there is no picture on the screen but sound.

See more | Go to post
Leave a comment:
tmhobadcap replied to Lithium ion cell voltage not going up after 3.8V

in General Electronics Technical Discussion

02-04-2025, 03:33 PM
Sorry, I do not have the original power adaptor....

See more | Go to post
Leave a comment:
tmhobadcap replied to Lithium ion cell voltage not going up after 3.8V

in General Electronics Technical Discussion

02-04-2025, 01:52 AM
According to the label on the chrome book, the input voltage is 19.5V....

1 Photo

See more | Go to post
Leave a comment:
tmhobadcap replied to Lithium ion cell voltage not going up after 3.8V

in General Electronics Technical Discussion

02-03-2025, 10:08 PM
Thanks for your comment.
Sorry, I did not post the outer packing of the battery pack. Also, there is markings on the cell, but I just do not know what it means. Here they are.
The markings show 7.7V which I think should be the nominal voltage. Then the maximum or full voltage for each cell should be 4.2V. Did I make a mistake?...

See more | Go to post

Last edited by tmhobadcap; 02-03-2025, 10:18 PM.
Leave a comment:
tmhobadcap replied to Lithium ion cell voltage not going up after 3.8V

in General Electronics Technical Discussion

02-03-2025, 10:01 PM
Thanks for your comments. But they did not answer my question.
My cells are not swollen. When charging, they were cool....

See more | Go to post
Leave a comment:
tmhobadcap started a topic Lithium ion cell voltage not going up after 3.8V

in General Electronics Technical Discussion

02-03-2025, 01:30 PM
Lithium ion cell voltage not going up after 3.8V

I got a chromebook with battery problem. It was charging when plugged in. But the indicator just showed that the battery was below 10% no matter how long it was plugged in. I took the battery pack out. There are two cells in series. Each cell had a voltage of about 3.7V. I charged one of them with a lithium cell charger. I can see current going into the cell at about 500mA. After several hours, the voltage was just about 3.8V. I charged it again manually by connecting 4.2V to it from a power supply and set the maximum current to 500mA. I can see about 100mA going into the cell. But the voltage...

2 Photos

See more | Go to post

Last edited by tmhobadcap; 02-03-2025, 01:32 PM.
tmhobadcap replied to Any special techniques in desoldering this rectifier?

in Equipment Usage, Soldering, Techniques, and Reviews

08-21-2024, 09:33 PM
Thank you for this suggestion.
I will try it....

See more | Go to post
Leave a comment:
tmhobadcap replied to Any special techniques in desoldering this rectifier?

in Equipment Usage, Soldering, Techniques, and Reviews

06-30-2024, 08:50 PM
Thanks for your suggestions.
Yes, it is difficult to do so with just a soldering iron and soldering wick. Finally, I used a heat gun to desolder it....

See more | Go to post
Leave a comment:
tmhobadcap replied to Any special techniques in desoldering this rectifier?

in Equipment Usage, Soldering, Techniques, and Reviews

06-29-2024, 12:27 PM
Thank you!...

See more | Go to post
Leave a comment:
tmhobadcap started a topic Any special techniques in desoldering this rectifier?

in Equipment Usage, Soldering, Techniques, and Reviews

06-29-2024, 02:42 AM
Any special techniques in desoldering this rectifier?

I need to desolder a bridge rectifier as shown on the attached photos. I found that two of the four holes are different from the other two holes. The middle two holes have something like a metal ring on the hole. Is there any reason for this? When desoldering, is special technique and/or equipment needed?

2 Photos

See more | Go to post
tmhobadcap replied to Samsung un65h6203af led replacement question

in Troubleshooting TVs and Video Sources

10-04-2023, 09:20 AM
Re: Samsung un65h6203af led replacement question

Thanks for your suggestion. I have placed the order for the led strips.

But I still would like to know the answers to my above questions. They would be useful for me in case I have another tv which needs only to replace just a few leds....

See more | Go to post
Leave a comment:
tmhobadcap started a topic Samsung un65h6203af led replacement question

in Troubleshooting TVs and Video Sources

10-03-2023, 11:37 PM
Samsung un65h6203af led replacement question

This tv is with sound but no picture. When light shines on the screen, we can see the image. This is a typical backlight problem. I opened it and found quite a lot of the leds are damaged. But the damaged ones are all shorted. No one is open. Is there a special reason? (From my past experience, both can be happened)

When I supply 3V to each of the good leds, the currents range from 105mA to 154mA. From these figures, I think the leds are 3V and about 0.5W. I plan to replace all the damaged leds only (because the price of the led strips is very expensive), but I could not find 3V 0.5W...

See more | Go to post

Last edited by tmhobadcap; 10-03-2023, 11:50 PM.
tmhobadcap replied to Asus vz239h-w no display

in Troubleshooting Computer Displays

08-08-2023, 01:44 PM
Re: Asus vz239h-w no display

Sorry, I made a mistake. I mentioned that there were no voltages on all capacitors after turning on the monitor. That is incorrect. I just found that the power plug is loose making no contact at certain angle and so I could not get any voltage. But the no display problem and other founding are still true.
I am now trying to check which components might be defective by following the service manual provided by Lisa Su.

See more | Go to post
Leave a comment:
tmhobadcap replied to Asus vz239h-w no display

in Troubleshooting Computer Displays

08-07-2023, 01:38 PM
Re: Asus vz239h-w no display

Thanks a lot Lisa Su.

See more | Go to post
Leave a comment:
tmhobadcap started a topic Asus vz239h-w no display

in Troubleshooting Computer Displays

08-05-2023, 04:12 PM
Asus vz239h-w no display

When I turn on the monitor, the screen does not light up. But when I shine light on screen, the ASUS LOGO image can be seen. But after a few seconds, the logo disappears and the power light turns orange which means standby.

I have checked backlight leds, they are all working. That means not backlight led problem. In other words, there is power to the backlight leds.

I found that when turned on, there is no voltage on all capacitors. So I suspect that something wrong with the chips. I started with the two chips closest to the power input, the one with the markings of "P8019...

See more | Go to post

Last edited by tmhobadcap; 08-05-2023, 04:30 PM.
tmhobadcap started a topic Vizio M55-F0 Cannot be turned on

in Troubleshooting TVs and Video Sources

07-08-2023, 12:58 PM
Vizio M55-F0 Cannot be turned on

I found this tv's situation is very complicated. It will take a long time for me to tell what I found. Therefore, if you don't mind, before I tell the complete story of what I found, I would like to ask some questions. Of course, if the complete story is needed, I will do so.

The tv cannot be turned on. I found that the heat sink on the mainboard is so hot to touch even if it is just plugged into the wall outlet but without turning on the tv. Does this indicate that something wrong that needs to replace the mainboard or the other boards?...

See more | Go to post
tmhobadcap replied to Samsung UN60ES6100F black screen with standby led flashing 5 times

in Troubleshooting TVs and Video Sources

05-26-2023, 03:18 PM
Re: Samsung UN60ES6100F black screen with standby led flashing 5 times

Sorrry, finally I did not fix it....

See more | Go to post
Leave a comment:
tmhobadcap replied to Hisense 58H6550E - Freezes/Won't turn on

in Troubleshooting TVs and Video Sources

02-20-2023, 03:53 AM
Re: Hisense 58H6550E - Freezes/Won't turn on

Like this post ([url]https://www.aliexpress.com/item/1005003960973294.html?spm=a2g0o.cart.0.0.732938da8sYbgY&mp=1[/url]), they have different diameter for the balls. Which one should I choose?Re: Hisense 58H6550E - Freezes/Won't...ould I choose?Re: Hisense 58H6550E - Freezes/Won't turn on
...

See more | Go to post
Leave a comment:
tmhobadcap replied to Hisense 58H6550E - Freezes/Won't turn on

in Troubleshooting TVs and Video Sources

02-19-2023, 09:16 PM
Re: Hisense 58H6550E - Freezes/Won't turn on

From the codes on the chip, I can find the datasheet [url]https://www.datasheets.com/en/part-details/h26m52208fpr-sk-hynix-inc-98770818#datasheet[/url]. But on the datasheet, I could not find the stencil size and ball size. Can you give me more hints on how to find the stencil size and ball size?

One more question. This chip was programmed by Hisense. But the one on the market is not programmed, therefore, I can buy one and replace the current one. Am I correct? Or if there is a way to program the chip? Or will...

See more | Go to post

Last edited by tmhobadcap; 02-19-2023, 09:25 PM.
Leave a comment: