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Last Activity: 02-11-2024, 09:00 AM
Joined: 07-21-2014
Location: Southampton
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  • case sensitive
    started a topic BN44-00472A power off loop
    in Troubleshooting TVs and Video Sources

    BN44-00472A power off loop

    Hi I have a Samsung BN44-00472A from a UE32D4003BW.
    The TV didn't power on and I found that ICM801S (STR-W6053S) was shorted and the fuse FM801S had blown so I replaced both of those.
    The board now powers on for around 1 second then there is a click and it powers off, this repeats until AC power is removed.

    I've checked the main rails on the cold side and resistances to ground look sensible:
    B13v / Vamp: 23K
    B5v: 216 ohms (schematic shows a 220 ohm resistor connected between it and ground)
    A5v: 1.5M and falls slowly
    Vdrv: 6M and falls slowly...
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  • case sensitive
    replied to HP 15-ab271sa repair
    in Troubleshooting Laptops, Tablets, and Mobile Devices
    Re: HP 15-ab271sa repair

    I have a backup so can try flashing that back.

    One thing I didn't notice before is that as soon as I plug the charger in (before pressing power button) the board actually powers up the 3.3, 5 and VCC_CORE rails (I just thought it turned the LED on), no 1.05v though.

    Kind of stumped at this point, all the power rails are there at various times just never all at once and it clearly shouldn't be powering on the moment the charger is plugged in.

    I can't see any mention of a 1.8V rail in the schematic. VCC_CORE is 1.7V though,...
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  • case sensitive
    replied to HP 15-ab271sa repair
    in Troubleshooting Laptops, Tablets, and Mobile Devices
    Re: HP 15-ab271sa repair

    All the main power rails except VCC_CORE seem to be powering on now (which is strange because I had 1.7v on VCC_CORE before flashing the bios).

    So currently what happens when I press the power button is:
    1) 3.3 and 5v turn on
    2) board powers off (leds and 3.3/5v turn off)
    3) board powers back on
    4) 3.3, 5, 1.05, 1.5 and 1.35 (ram) power on for less than a second, no VCC_CORE
    5) power off again

    VRON from the SIO is 0v but I'm not sure at what point that is supposed to turn on.
    VR_ENABLE and VR_READY...
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  • case sensitive
    replied to HP 15-ab271sa repair
    in Troubleshooting Laptops, Tablets, and Mobile Devices
    Re: HP 15-ab271sa repair

    OK after reprogramming the bios chip there is some progress. The board will now reliably attempt to power on and the power LED on the other side of the board (from DC jack) now turns on (didn't happen before). It will then power off and the DC jack and power LED will flash once before turning off again.

    As far as I can tell 3.3, 5 and 1.05v are powering on but it's so quick it's had to catch with the multimeter.

    Is 0.6v AD_ID correct? The behaviour is the same when the battery is connected.
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  • case sensitive
    replied to HP 15-ab271sa repair
    in Troubleshooting Laptops, Tablets, and Mobile Devices
    Re: HP 15-ab271sa repair

    0.6v for AD_ID at the DC jack and SIO, AD_TYPE is 0.6v too.
    I have a spi programmer so will try that, thanks.
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  • case sensitive
    started a topic HP 15-ab271sa repair
    in Troubleshooting Laptops, Tablets, and Mobile Devices

    HP 15-ab271sa repair

    Hi, I have an HP 15-ab271sa that I'm trying to repair, the board (Quanta X12A) doesn't power on.

    The problem manifests itself in one of two ways:
    1) The LED on the DC jack switches off briefly when the power button is pressed (then back on) and the 3.3V rail powers on for a few seconds before switching off.
    OR
    2) (rarely) the DC jack LED stays off after pressing the power button and 3.3, 5 and VCC_Core all power on (and stay on). 1.05V and 1.35V (RAM) are not present. When this happens HWPG (power good?) is 0V which I assume is why I don't get 1.05 and 1.35V....
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  • case sensitive
    started a topic Samsung LE37C650 buzzing
    in Troubleshooting TVs and Video Sources

    Samsung LE37C650 buzzing

    Hi,
    I have a Samsung LE37C650 TV that makes a loud buzzing noise in dark scenes and at any time if the backlight is set to anything below 20 (range is 0-20). Upon further research this seems to be a very common problem with this TV but I can't seem to find a fix posted online yet.

    I first tried replacing the capacitors on the inverter board then replaced all capacitors on the power supply except the large 450V cap. On both occasions this seemed to fix the problem initially (almost no buzzing in dark scenes and no buzzing at all with the backlight turned down) but after a few...
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    Last edited by case sensitive; 11-07-2018, 06:24 PM.
  • case sensitive
    replied to Dell 3008wfp faulty power supply
    in Troubleshooting Computer Displays
    Re: Dell 3008wfp faulty power supply

    Uploaded a video of what happens (epilepsy warning!!):

    [URL="https://youtu.be/pyA_5wPEIKQ"]https://youtu.be/pyA_5wPEIKQ[/URL]Re: Dell 3008wfp faulty power supply

    Uploaded a video of what happens (epilepsy warning!!):

    [URL="https://youtu.be/pyA_5wPEIKQ"]https://youtu.be/pyA_5wPEIKQ[/URL]
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  • case sensitive
    replied to Dell 3008wfp faulty power supply
    in Troubleshooting Computer Displays
    Re: Dell 3008wfp faulty power supply

    Hi, sorry if this is a bit of a long post but I'm having a problem with my 3008wfp.

    I replaced the D22 over 3 years ago now and that's still going strong however a few months afterwards I started to notice a single yellow line going down the screen.
    The line goes away when the monitor has warmed up so I pretty much ignored it until a couple of months ago.

    I opened it up to try to fix the line (thought it might be a capacitor or tab bond) and to add a fan to get rid of some of the heat these things produce....
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  • case sensitive
    replied to Dell 3008wfp faulty power supply
    in Troubleshooting Computer Displays
    Re: Dell 3008wfp faulty power supply

    Thanks Lumberjack, that's what it was. Managed to free it by removing the screws in the central black piece of plastic, separated the very back piece from it in that corner then freed the metal tabs. One of the tabs had become quite bent but it's ok now.
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  • case sensitive
    replied to Dell 3008wfp faulty power supply
    in Troubleshooting Computer Displays
    Re: Dell 3008wfp faulty power supply

    I've read it but I'm not sure about step 7.
    I can't see any clips holding the back to the metal body, why would they only be in one corner of the monitor?

    I have now managed to completely remove the front bezel (step 4), there appeared to be some tape holding the power button cable down.
    See more | Go to post

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  • case sensitive
    replied to Dell 3008wfp faulty power supply
    in Troubleshooting Computer Displays
    Re: Dell 3008wfp faulty power supply

    Hi everyone, new to the forum. Been looking through this thread because I was given one of these monitors the other day. Nothing happens when the power button is pressed so I have ordered the replacement diode.

    I was wondering if someone may be able to help me, I am having an absolute nightmare trying to open this thing.
    I have managed to separate the bezel so that it's just held on by the power button cable then I flipped the monitor over.

    On the side with the card reader the panel drops out fine (just gets...
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