I recently got my hands on a model 2493HM. At first the power led would just blink blue and never show anything on the display. After opening the unit, i found a bad cap on the power board. I replaced it, but when i was reassembling the monitor i noticed a rattling sound coming from the logic board. It sounds like a small piece of metal is caught somewhere and is rolling around. I would normally not pay this any mind, but now i get a solid blue led and no display. Any suggestions?
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Re: Samsung 2493HM issue
1) Replacing the one obviously bloated cap may not be enough. Capacitors die from age, heat, and shoddy build quality. Capacitors DO NOT have to be visibly bloated in order to bad. They can be out of tolerance uF (a 1000uF measures 20uF) and/or have high ESR (ohm). A multimeter will be insufficient to test for ESR. For that you need an ESR tester which costs between $50 and $300.Originally posted by werthles View Post
2) What brand and series did you use for a replacement cap?
3) If you hookup a computer displaying your favourite wallpaper, can you see it by shining a flashlight on the lcd?
4) If you have no display, check your voltage regulators on the logic card.--- begin sig file ---
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Re: Samsung 2493HM issue
The rattling may be a rotation sensor.Comment
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Re: Samsung 2493HM issue
I just stripped a capacitor off of another motherboard. I did make sure that it had equal capacitance and it actually was a larger voltage. Im not sure of the brand. I hooked the monitor up to my computer and held a flashlight up to it to no avail. I did not see anything on the screen.Comment
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Re: Samsung 2493HM issue
This would be a good time to post some good focused photos of the top and bottom of your power board. Photos of the logic and inverter boards would also be good.Comment
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Re: Samsung 2493HM issue
That used cap could be dry and also bad as well.Originally posted by werthles View Post--- begin sig file ---
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Re: Samsung 2493HM issue
Ok, ill take some photos of it once my camera charges up. Ill probably just order some caps and replace the majorit of them.Comment
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Re: Samsung 2493HM issue
Here are some closeups of both boards.Attached FilesComment
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Re: Samsung 2493HM issue
If i were to replace all the caps, what brand would be preferred/suggested? Thanks in advance.Comment
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Re: Samsung 2493HM issue
1) For the power board, we need a top down view of the board.Originally posted by werthles View Post
2) Still waiting for answers to questions #3 and #4 in post #2.
3) Forum members here like Panasonic FR, FM, and FC (in that order). Other good quality caps are listed in the FAQ section at
https://www.badcaps.net/forum/showthread.php?t=2280
Badcaps.net sells Rubycon.
4) You must use low ESR caps for a SMPS application.--- begin sig file ---
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Re: Samsung 2493HM issue
I did the flashlight check on the monitor and i did not see anything. As i am quite new to this, im not sure how to check the voltage regulator on the logic board. Any help with that would be appreciated.Attached FilesComment
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Re: Samsung 2493HM issue
1) What is the part number for the red circled component?Originally posted by werthles View Post
2) What is the part number for the yellow circled component?
3) To measure the DC voltage of a voltage regulator, put your multimeter on 20V DC. Plug in all boards and plug in the lcd into the AC outlet.
Put your black probe on a ground screw on the logic board. Put your red probe on each of the individual pins of the circled components. List the DC voltage for each component and pins.Attached Files--- begin sig file ---
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Re: Samsung 2493HM issue
Red circled chip: 6P741
Yellow circled chip: (brand: ST) LF25GKDK7747Comment
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Re: Samsung 2493HM issue
Well, in trying to test the voltage regulator i got some good sparks flying. Unfortunately how they built this thing it was impossible to fully assemble without the back panel and test the leads. I had to set it up where the logic board and power board were hovering over each other. Needless to say, as soon as i hooked it up i got shocked and i saw some sparks when i was trying to disconnect it. Now, fully assembled, the led wont even light up. Is it completely dead?Comment
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Re: Samsung 2493HM issue
I usually use cardboard to separate the boards if needed.Originally posted by werthles View Post
If you have no LED at all, you probably shorted something out. I wouldn't say it is completely dead, but we will now have to troubleshoot what components are shorted out or blown.
With power off and the lcd unplugged, check the following.
1) Check the two fuses by the AC input. A good use should measure less than 1.0 ohms.
2) There is a bridge rectifier (long black) just below the 2J 474J white capacitor. Number the pins 1, 2, 3, and 4. Set your multimeter on 200 ohms. Measure 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4. Any reading under 30 ohms suggests it may be shorted.--- begin sig file ---
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Re: Samsung 2493HM issue
It would also help if you could give us an overall picture of the boards when everything is assembled so we can see how you are testing it using a multimeter. That way, we can suggest test points that are easy to reach for the multimeter probes.--- begin sig file ---
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Re: Samsung 2493HM issue
I should explain the troubleshooting process here.Originally posted by werthles View Post
When the LED is green/blue, but you don't see the computer wallpaper with a flashlight, this implies that something is wrong with the logic board. That is why we are checking the voltage regulators on the logic board.
If the LED is green/blue and you can see an image with the flashlight, that implies something wrong with the inverter board or ccfl.
If you have no LED, that implies that there is something wrong with the power supply and/or the logic card.Last edited by retiredcaps; 02-16-2011, 12:43 AM.--- begin sig file ---
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Re: Samsung 2493HM issue
Yeah, im getting no reading on either of the fuses. I tried all ranges of ohms.Comment
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Re: Samsung 2493HM issue
If you mean "1" on the left hand side of the multimeter, then both of your fuses are blown. Don't confuse "1" on the left hand side of this display with 1.0 on the right hand side. The first means out of range and the second means 1.0 unit of your measurement.Originally posted by werthles View Post
You obviously want to order replacements (maybe 4 or 5 in case it blows again), but you also want to check out the bridge rectifier as well before installing the new fuses.--- begin sig file ---
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Re: Samsung 2493HM issue
Now i just need to find out what kind of fuse they are.Comment
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