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Old 08-22-2016, 12:50 AM   #61
stevwills
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Default Re: A guide on how to troubleshoot 2 seconds to black

Quote:
Originally Posted by stevwills View Post
the both lamps don't turn completely on. they kinda turn on like a loading screen. (they both go at the same pace.) and before they hit the end, the monitor turns off.

when is say the monitor turns off, i mean only the panel. the speakers and the power led stayes on.
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Old 08-22-2016, 04:58 AM   #62
mikail13
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Default Re: A guide on how to troubleshoot 2 seconds to black

SAMSUNG P2270HD
2 Second to black

other parts are O.K. ie. CCFL.
this power board kills my life...

everthings seems O.K.
i.e. caps. i test them on board.

any idea?
Attached Images
File Type: jpg Samsung p2270HD power.jpg (1.41 MB, 40 views)
File Type: jpg p2270HD.jpg (1.48 MB, 32 views)
File Type: jpg P2270HD BOARD.jpg (1.44 MB, 32 views)

Last edited by mikail13; 08-22-2016 at 05:27 AM.. Reason: ADD Pic
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Old 08-22-2016, 09:01 AM   #63
budm
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Default Re: A guide on how to troubleshoot 2 seconds to black

You should make a thread regarding to your monitor, this thread is for the guide only, not for any particular model.
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Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/

TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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Old 08-23-2016, 02:50 AM   #64
mikail13
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Default Re: A guide on how to troubleshoot 2 seconds to black

i get it. it can delete. how can i move the post and pics?

i re-upload pics on new thread..

please delete my last two post on there..

Last edited by mikail13; 08-23-2016 at 02:58 AM.. Reason: solved
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Old 09-27-2016, 06:29 AM   #65
b19_george
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Default Re: A guide on how to troubleshoot 2 seconds to black

Hello, I have an Benq ET-005-N with backlight problems, the CCFL lamps are not starting at all but i test them and are fine, I know the monitor works because I used another board to fire up the CCFL lamps and once the lamps are on you can see the image on the screen, the caps are replaced are not bulging and tested for capacitance, the transformers have the same resistence both of them (0.63K) so either are both damaged or is the right reading. Any advice will be more than helpfull!
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Old 12-16-2016, 04:23 PM   #66
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Default Re: A guide on how to troubleshoot 2 seconds to black

I have two identical 27 LED monitors to fix. Both of these seem have this 2s to black type problem where they seem to power up, an image flashes briefly then they go back to standby.

I have a lot of experience in fault finding circuits but not with LED Monitors/TVs. Before I get going Id like to ask some general advice.

Specifically Id like to get some advice on how to test the PSU isolated from the logic boards. I can see that there are various fault conditions where the power is shutdown deliberately by protection circuitry for instance going into standby when there is no signal, shutting down then the backlights are faulty etc. Id like to know how to test the PSUs in LED monitors/TVs with the logic circuity and screen unplugged so that I can check the PSU itself first. As far as I can tell, if the PSU is simply unplugged from the logic circuits, it would remain shutdown like a PCs ATX PSU does, so couldn't be tested without some test circuitry.

There are two reasons I want to approach it this way:
1) I want to isolate the problem. For this type of issue where the appliance seems dead it is logical to test the power supply first, and
2) These devices are clearly very dangerous to run live. I do have experience working with high voltage circuits (upto 1kV). The best advice for these is to avoid live diagnosis of the HT areas as much as possible. These circuits could be deadly. Having a methodical way of testing these would make the process safer.

I guess the advice to do this would apply to many monitors. The monitors I have are HP ZR2740W. I can't find the circuit diagrams for these so I cant work out the answer to this easily myself. Ill start a new thread for these monitors but if there is general advice perhaps it is best for people to find here.

Thanks in advance!
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Old 01-21-2018, 12:51 PM   #67
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Default Re: A guide on how to troubleshoot 2 seconds to black

Don't wanna hijack anything here in the topic, but I'm wondering how likely it is to have a bad high voltage cap. I have a topic here: https://www.badcaps.net/forum/showthread.php?t=66726

I'ts a bout a LG monitor with CCFL backlights, and the backlight goes off after ~ 3 seconds, while the image and everything stays perfectly on (of course only visible with a flashlight). I already replaced the regular caps, but it didn't change anything. So I was thinking about replacing the big capacitor (120F 450V). However in the Cap kits you can buy for monitors I never see the big capacitor being in the kit, nor did I see anything here in the troubleshoot topic mentioning the big cap.

Is this thing likely to fail, or is that very rarely the case?
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