Learn about how CCFL fails

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  • ttmi100x
    HANNSG Hi221 -- 2 secs to black feat. CCFL flicker & "burn" marks on power board
    by ttmi100x
    Greetings everyone,


    I have a HANNSG Hi221 monitor that exhibits two seconds to black issues (backlight goes off, display is still on as confirmed by shining a flashlight on it) with some additional oddities...


    The monitor failed on me with a standard "2 seconds to black" some time ago prompting me to initially replace most of the electrolytic capacitors (some of them were bulging/leaking).
    Things kinda sorta worked for a night, then the problem returned along with some flickering and "buzzing" noises.

    Upon closer inspection...
    07-31-2024, 06:36 PM
  • mikey5791
    Help on Samsung Syncmaster T220 dead ccfl lamp
    by mikey5791
    Hi,

    This monitor previously is my main working monitor which i have been using for 8~9 years. Yesterday, when i switched on my pc from fresh to power on, the monitor is just black no display. I started dismantle to look inside the monitor power board but nothing looks suspicious or burnt. So i took my external ccfl inverter to try to power the monitor ccfl lamps which consisted of 2 lamps on upper part and 2 lamps on the lower part.

    Found out the upper ccfl lamp which is supposed to connect to cn304 on the power board did not light up. Then i installed a used working...
    10-18-2020, 03:17 AM
  • eliasseverholt
    Looking to learn about troubleshooting my Lenovo L14 Gen 1
    by eliasseverholt
    Hello!

    Unfortunately my Lenovo L14 Gen 1 (motherboard NM-C741) was involved in a terrible mishap. At first, one of my friends accidentally spilled coffee on it which made some of the ports stop working but the computer worked fine otherwise. After that I stupidly opended it and forgot to disconnect the battery... One thing leads to another and I accidentally short it between two components (unfortunately I do not remember which components). After that I get nothing, no charging indication, no boot indication, no fan spin, nothing.

    So I'd love to learn my mistakes and...
    12-19-2023, 06:13 PM
  • signal.quest
    Samsung LN40C630K1F LCD TV No Backlights and Flashlight Test Fail
    by signal.quest
    Hi all,

    I have been working on a Samsung LN40C630K1F LCD TV. On power up the backlights only briefly light up when first powered on then they go out (2 seconds to black). The flashlight test also fails. The sound works fine. Please see attached pics.

    I have researched the forums a lot. I have watched the videos of trying to locate the bad CCFL or transformer and bypassing. I can't find any evidence of a bad transformer/CCFL. I verified I get 376V from the big caps to the fuse. I have used a small/cheap oscilloscope and it looks like the MOSFETs on the inverter...
    09-30-2024, 11:21 PM
  • nath1977
    Samsung F7000 occasionally cycles and fails to switch on
    by nath1977
    I have a UE40F7000 Samsung which occasionally fails to properly come out of standby. The relay clicks and the backlight flashes but then goes off again with a click, and repeats. I think its temperature related as leaving it overnight seems to allow it to switch on OK.

    I assume its PSU related and had a look - it's a BN44-00632B. No signs of swollen caps or hot components.

    I saw a great YouTube video on a possible PFC related issues and an underrated resistor https://youtu.be/DREofE4WIvg?feature=shared though a quick trace from the SPC7011F pin 7 lead me to a resistor...
    12-27-2024, 11:10 AM
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