Today a customer brought a 19″ LCD monitor with name MOGUL on it. (By the way, it’s one of Mongolian PC brands). When plugged it to power outlet there was no power LED, nothing. Customer says maybe it’s just a fuse, but I don’t agree with it.
I’ve removed the back cover and there are only 2 small boards. One is the inverter for back light, other one is tiny power supply board compared to other monitors. 3rd PCB is under another metal cover, since I have power supply board at hand I won’t remove this metal cover.

lcd monitor repair

First I’ve checked the fuse by multimeter, but it was OK. Then I quickly checked some other components in following order: – bridge rectifier, visual check of main capacitor for any bulge. They were also OK. Then I soldered a wire on (-) leg of main capacitor and clipped it to one probe of oscilloscope. After plugging the power supply to AC mains I measured for impulses on FET transistor and transformer but there were none. There are no impulses on primary side of the transformer there is no output on secondary side. I suspected FET, but it was tested good offboard. I also unsoldered tiny SOT23 SMD transistor H1P from the bottom side of the PCB, but it tested normal again. Since there were only few components I checked 2-3 resistors and diodes for open, they were all normal. Then remained only one yet most important component: an SMD IC chip labeled 1271A. As I saw high voltage and ground pins of this IC it became clear that it’s just the same IC as 203D6 which I have few of them in my stock. After replacing this IC impulses returned, appeared output voltages and LED and display turned ON.

repair lcd monitor mogul

What might be the reason for the damage to the IC? I suspected loose AC connector and asked the customer, then she says they have new AC cord which came with the monitor, but it went loose into monitor back connector and they heard noises coming from that connector. The repair work only took me 30 minutes because the the power supply board was the simplest one I have ever seen.

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About

Electronics repairer based at Ulaanbaatar, Mongoilia. Contact e-mail: damdin88@yahoo.com

6 comments on “LCD Monitor Power Supply Repair

  1. Gary Nichols says:

    I have a V223W power inverter (ID# E59670) (ILPI-075 for B223W) there are No blown or bad capacitors. I have tested them with a Fluke 16. No burnt connections. It will power on but only for a few seconds and then shuts down? Anyone seen this issue before? Thanks

    1. Damdin says:

      Hi, Nicholas!
      Please check your LCD lamps. If one is bad the situation is same as like yours. If you look carefully maybe you'll find bad lamp's end became dark or broken, if you hear there is hiss noise around the bad end of lamp, and strong ozone smell too. All these are symptoms of bad LCD lamps.

  2. siddiq shaheen says:

    i want to see display card ( logic card) of view sonic lcd monitor VA1716W-4 Model VS11826
    because i have this LCD but in display card i think 2 capacitor are missing
    I am also doing repairing cores i will sent to your pictures of my LCD monitor cards
    power supply out put volt is good but even then power on button does not work i suspect that the display card does not deliver accurate volt to flex able cable that go to power on button.
    that sway my lcd does not have power.
    kindly help me
    thanks
    please send to me reply on
    telri77@hotmail.com

  3. rmhbc50 says:

    hi sir u r tell to me my problem SMD IC chip labeled 1271A ic and replace other number

  4. rohit says:

    i have also same board having ic 203d6,but its fet is missing.could you pls tell me which fet to use.thank you.

  5. Abu-Hafss says:

    A component on the power supply board of my Viewsonic VA1716W-4 blew all of a sudden. It was 6-pin (TO-220 package, plastic body) regulator attached to a fairly big heatsink. I'd found service manual for VA1716W-2 which showed same monitor as mine but the schematics and PCBs were different. The board shows component no. U101 but the manual did not showed such number. Nor cud I find any 6-pin IC in the schematics.

    Can you please identify the IC? Is it STR-W6765, the one used in Toshiba TVs?

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