Coby LEDTV5028 - another blue light special

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  • smalltownguy
    Senior Member
    • Feb 2010
    • 127
    • US

    #1

    Coby LEDTV5028 - another blue light special

    Picked up a Coby LEDTV5028 from work a few weeks ago. Location manager was telling me that at times they only way they could get the TV to turn on correctly was to unplug it for a few minutes.

    Brought it home, it fired right up. Turned it off and on a few times, no issues. Turned it off once more and this time when I tried to power it on, the LED standby light flashed bright for a split second, then went out and the set did not turn on. Unplugged the set for 30 seconds, pugged it back in. Waited for standby light to come back on again. Tried turning it on again. No dice. Light would glow bright for a split second, then flash out and the TV will not turn on. No response from the remote or on-board buttons.

    Bought a known working replacement power supply board, problem persisted.

    Bought a known working main pcb, and the problem went away, but since the main pcb I purchased was from a 39" TV and not a 50" one, the image did not display correctly on the screen. Further inspection revealed a few non-populated components in the corner of my replacement board. So I had to send that one back.

    So I know the problem is localized to the main pcb on the TV, and I believe it to be an eprom issue. I think what's happening is that sometimes the TV's main pcb locks up upon shut down/standby, and once that's happened, it will not turn on again until the main pcb is rebooted.

    Unplugging the set and holding the power button for a second or two will drain all the voltage from the main pcb. Once you've completely drained all the power from the main pcb, plugging the TV back in brings it back to life and it functions normally until it locks up in standby mode again.

    That would explain why location management could unplug the TV when they weren't using it and it would work for them when they plugged it in.

    I've been on the hunt for a replacement main pcb, but I've yet to find one from an LEDTV5028. The same pcb (002-LT23-7612-00R) is found in a few other Coby sets, but there are some components on the one used in my 50" LEDTV that are not found on the boards I see on eBay. I need to try and find one in stock somewhere that is a match to my board.

    In the mean time, I guess I'll continue to use the panel with the aforementioned condition - you have to unplug it when you're done using it. A minor annoyance, but at least it's usable until I find the correct replacement part.

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