Someone gave me this monitor to see if I could fix it. I pluged it into my computer for three day without a problem. Today I turned on the computer and the green light on the monitor came on but no picture. I tried unpluging it and then pluging it back in and it came on for a few secconds and went off again. Whyle it was plugged in I took a flash light and shone it against the screen and I was able to just barely able to make out the image of my desktop. So aparently the back lights have gone out but come on again when I plug it back in. What do you suppose the problem is?
Robert_adams, your problem is not uncommon. How old is or how many in use hours does this monitor have? Is it under warranty? This sounds like bad power supply(SMPS and or Inverter) which are needed to generate an 800-1500v ac to light -up the thin, straight, Cold-Cathode-Fluorescent Tubes used for backlighting the LCD/FPD . If out of warranty Check to see about a swapout program. you send them your's+$50-$90 they send you same model refurbished(new ccf tubes and inverter/smps. or find local guy to do repair. But this one sounds like you could do it all by yourself. If you have a DMM and large magnifying glass, or 10x-30x inspection microscope you might be able to see the bad solder joints on the switch mode power supply and the swollen electrolytic capacitors on the board. look on youtube for videos of lcd monitor disassembly or lcd repair videos. Let me know what your going to do before you do it. I will guide you with hints and kinks. Ihave repaired 2 of these things. Here is hint #1 Take pictures as you disassemble!!! I'm louie12fix on fixya or lmistyrel@ aol.com BYE for now.
Bob, You need to inspect visually the larger board first!! It's the one with large transformer on it. please inspect the verticle aluminum electrolytic "CAN" capacitors on this board. The tops of them should be flat and never appear to be raised such as a bad mosquito bite on your arm might be! If any of them are swollen, they will need to be replaced with new ones. Tell me if there also appears to be 4 more smaller FERRITE TRANSFORMERS on the board and are near smaller connectors that have 2 wires each and feed the high voltage to the left and right of the lcd panel. All of the bottom side solder connections must be inspected for thermal/vibration fractures around the leads of the "Through-Hole" components mounted on the top side. I found 6 of these on one SMPS from a DELL monitor. Yes, I use an old post WWII Baush&Lomb microscope to find these things. Let me know what you find. lmistyrel@ aol.com Do send email to me and I will try to forward a reply that I received from another guy who sent me attached photo of his inverter board. BYE for now.
This is a huge indicator of a bad inverter transformer. In simple terms: this transformer (responsible for powering the backlights) is shutting down because it's overheating. Therefore, there's no juice to the backlight and the screen goes black. When the transformer cools down again, the backlight will come back on, but only until the transformer overheats and kills power to the backlight AGAIN. A vicious cycle until the transformer finally has it.
I had one once that I was able to watch as it sparked when I had the backpanel off. Pretty scary. I desoldered it, pulled off the insulation tape and saw burnt separation bars inside and partially RED windings (indicator of overheating). Good luck finding replacements, digikey.com might have them
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This is Bob again,
The monitor has developed a new problem. I pluged it into the VGA connection on two diffrent computers and when I turned it on the power light turned green and the back lights came on just long enough to display a small very shaky box on the screen that read "NO SIGNAL" then went to black and the power light turned yellow. I believe the problem is a small circuit board inside (I've now dissassembled the monitor) with the part number M713 Rev 3 or M713-S3. It appears to have a CPU built into it but I have no way to test it. This board plugs into the VGA input and has a second connection that goes out to the screen itself. A third connection goes to the power switch on one pigtail and the control switches on another pigtail. This smaller board mates to a larger board that I beleave to be the back light power source from all the large capacitors and the transformer on it. Does anyone know where I might finda replacement for this board?
Hi It's Bob again. After dissassembling the monitor and checking all the solder joints and checking the capicitors starting with the big board and then the small board. I could find nothing phyisically wrong with the either. No swolen capacitors. As for the solder joints I used an old fashond magnifying glass out in the daylight and with a flashlite. I could find no bad joints on either board. Wouldn't the fact that when the power button is pushed the green light comes on, then the back lights come on for about 2 seconds with no info displayed on the screen then go out and the green light turns yellow mean that the power to the back lights is fine but the monitor is not receiving any information so it goes into sleep mode? Thanks, Bob
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