A guide on how to troubleshoot 2 seconds to black

[websk8r]

Re: A guide on how to troubleshoot 2 seconds to black

OMG! Exactly what i was looking for! retiredcaps Thanks a ton for putting together such an informative post. You have no idea how helpful it is for a newbie like me. Thanks again!

[stts]

Re: A guide on how to troubleshoot 2 seconds to black

Hello, It appears that I have two Shorted Transistors.

Transistors C5706

How can I know how to choose the right reference to replace these shorted transistors ?

Thanks

C5706 is short for 2SC5706. Newark electronics doesnt carry these stock but an internet search shows they are similar to 2SC3518. Its always wise to look at the pdf data sheets of each and see if they are similar enough.

[Feepit]

Re: A guide on how to troubleshoot 2 seconds to black

I'm having a similar problem with an Acer x223w where it powers on for a couple seconds and the power light stays on except that I see no display when shining a light on the screen.
Should I still try following these instructions or look elsewhere?

[budm]

Re: A guide on how to troubleshoot 2 seconds to black

@feepit, please start a new thread in the monitor forum and put the make and model of the monitor in the name tag, also post good clear pictures of the boards.

[YoshiCJ]

Re: A guide on how to troubleshoot 2 seconds to black

Thank you, this thread is amazingly helpful and well written!

[andyc]

Re: A guide on how to troubleshoot 2 seconds to black

Thank you! Very useful thread.

[ek2oo2]

Re: A guide on how to troubleshoot 2 seconds to black

Bad screen panel can cause 2 seconds to black. This time the behaviour is different. That is why, I am confused at first.

The loop is, 2 seconds to black when pushing the power button, i saw some reddish background and the "no signal" box, the LED will stay on for about 3 seconds then the screen flash again in another 2 seconds to black with the "no signal box" again, this time no reddish background. After that it's all black forever but with the LED still on. The LED in this case is blue and this not change colors.

I tried connecting the cable, and yes I can see images coming but only for awhile as this unit is always shutting down..

I'm guessing it's kinda rare issue. I tried searching for solution/s but I can't seem to find one. I replaced the panel with a known good one and it works smoothly. It's a Samsung CX743B. A 17-incher ccfl powered LCD monitor.

Just jotting it down for future reference and knowledge sharing purposes.

My theory is that there is a shorted component in the screen panel or it is slowly dying and showing signs of deterioration.

Good day to all...

[Frimp]

Re: A guide on how to troubleshoot 2 seconds to black

Thank you retiredcaps! You and the other members are very kind to share all of this information.

[xtremeskier97]

Re: A guide on how to troubleshoot 2 seconds to black

Very good info here! Thank you to all involved. Im hoping to get my display back up and running but will have to start a thread as it is very unusual, at least to me.

[electrojas]

Re: A guide on how to troubleshoot 2 seconds to black

Hello to you all. I hope that you can guide or direct me here. I have a 40 inch TCL LCD tv and am getting the 2 seconds to black issue. so far I have replaced the inverter board and gotten no change but my specific issue is that when I power it on, vertically I get half the screen to light up on the right and nothing on the left side then goes to standby and audio still works. I am baffled because when I first tested this issue the screen lit up very dim on the left and nothing on the right. after taking the tv apart and removing the original inverter board to look at the lamps, I reassembled the tv and upon initial power on after that it was the same problem but it had moved from the right being black to the left during the 2 seconds to black condition. Please help. Thanks all

[ERICSSON89]

Re: A guide on how to troubleshoot 2 seconds to black

woww. amazing post.
I'm thrill the way your explanation goes here.
l will will keep this in mind.
thanks alot retiredcap

[shijeesh]

Re: A guide on how to troubleshoot 2 seconds to black

Thank you very much retiredcaps sir.

[phenol]

Re: A guide on how to troubleshoot 2 seconds to black

Excellent tips, could save a lot of money and time.

<snip>
5) Bad CCFL
--------------

Pay ATTENTION as there is a VERY HIGH VOLTAGE (600V to 1000V)! No multimeter is required for this test.

The CCFLs light up the panel and they can be bad due to age, bad solder, bad wiring connection or a variety of reasons. The easiest way to test for bad CCFLs is to have a least one other good CCFL. If you see a pinkish/redish hue, this is a sign that your CCFLs are dying.

Let's assume that you have a LCD with 4 CCFLs (numbered 1 to 4) and a good spare. We are trying to narrow down which CCFL is bad by substituting in a good one.

Pay ATTENTION as there is a VERY HIGH VOLTAGE (600V to 1000V)! As a safety precaution, it might help to have someone around when you are doing this if something screws up.

a) TURN POWER OFF and unplug the monitor and wait 1 minute
b) disconnect CCFL #1 and plug in spare CCFL into spot #1
c) plug in monitor and turn monitor on - note if "2 seconds to black" occurs
d) TURN POWER OFF and unplug the monitor and wait 1 minute
e) reconnect CCFL #1 and disconnect CCFL #2 and plug in spare CCFL into spot #2
f) plug in monitor and turn monitor on - note if "2 seconds to black" occurs
g) TURN POWER OFF and unplug the monitor and wait 1 minute
h) reconnect CCFL #2 and disconnect CCFL #3 and plug in spare CCFL into spot #3
i) plug in monitor and turn monitor on - note if "2 seconds to black" occurs
j) TURN POWER OFF and unplug the monitor and wait 1 minute
k) reconnect CCFL #3 and disconnect CCFL #4 and plug in spare CCFL into spot #4
l) plug in monitor and turn monitor on - note if "2 seconds to black" occurs

If you have a bad CCFL, one of the tests above should show you which one. If you still have "2 seconds to black", then we can assume it is not due to a bad CCFL.

I would like to point out that this test will always fail with four "2 seconds to black" outcomes. This is because the unit will operate only with all of 4 lamps in good condition; if any of them goes bad then the feedback circuitry will either detect excess load (less likely) or no load at all (cracked lamp or wires) and will shut down the inverter to protect it.
This test, however, can isolate which, and how many CCFLs have gone bad as with the working lamp plugged in the picture would still be visible (for a short period) but quite dim. However, when the bad lamp is plugged in there would be no picture at all in that 2 (or less) seconds.

There's another interesting thing described in this thread, where a digital MM or even a capacitor connected at right place acts as confusing element for feedback protection circuitry and the picture will stay on even with 3 working lamps, hence no black picture symptom. This can sometimes be useful as the repair can be uneconomical. And after all, replacing the lamps is a tricky as one can score a perfect "hat trick" only to completely mess on the 4th attempt (usually on friend's panel ).
My point is, running LCD with 3 or even 2 lamps can still sometimes be acceptable until all of them die, but this requires finding a way to confuse protection mechanism by attaching something that the feedback sees as a good lamp.

Question is: what is the best and safest way to do it?

BTW: the "remains" of the monitor can then be used to build pretty good standalone CCFL tester.


Cheers.

[thunder77]

Re: A guide on how to troubleshoot 2 seconds to black

Thank you for this amazing tutorial!

In my case (RPC LCD - junk with PSU Mirage PI-170DTLA) it was one CCFL lamp; I tested with one took from a Samsung LCD and voila, evrika... no more 2 seconds to black!!! Of course I changed all caps and IC202 and IC203.

So, check the CCFL lamps! It's complicated to disassembly.

[guirnab]

Re: A guide on how to troubleshoot 2 seconds to black

<--- delete me --->

(moved to new thread)

[budm]

Re: A guide on how to troubleshoot 2 seconds to black

You should create a new thread for the question you have regarding to the monitor repair, this thread is for the guide on how to.

[theoneandonly77]

Re: A guide on how to troubleshoot 2 seconds to black

Thank you helped alot im still learning helped me tremendously

[lion_sta]

Re: A guide on how to troubleshoot 2 seconds to black

Quick question.

I have the 11P06 MOSFET (i hope it's a mosfet) and when connecting the red to the Drain and black to the Source I get 511 (diode mode) and a guy on Youtube says there shouldn't be.

Is it faulty?

[timko]

Re: A guide on how to troubleshoot 2 seconds to black

thanks a lot for the guide!

[stevwills]

Re: A guide on how to troubleshoot 2 seconds to black

Hello, i have an asus vh242h that does a ''2 seconds to black'' I have completely dissassemble the monitor. from what i can see, when i turn the monitor on, 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. I have a feeling its the power board. because of the symptoms its giving me. but i am definitely not an electrician. and i was wondering if someone with more tech savy then i do can confirm my theory.