UN55MU7500fxza Samsung Curve, Dead no picture

[Plurxtc1]

I have a Samsung Curve TV UN55MU7500fxza. There's no LED standby on the power button. I checked the connector to the mainboard where it needs 13V, it only showed up 9V. I removed the connector and the backlight comes up. I ended up replacing the mainboard but the issue is the same. The voltage drop and no LED standby. Have anyone experience the same problem with the curve? I came across a previous Curve TV and it caused the same symptom.

[R_J]

Re: UN55MU7500fxza Samsung Curve, Dead no picture

I believe the 9 volts is normal in standby, You need around 3.3~5v on the POWER ON pin to turn on the power supply and then you will get the 13v. The likely cause is the main board, I see there is an eeprom available for this model

[neilc6]

Re: UN55MU7500fxza Samsung Curve, Dead no picture

Do the backlights come on if you disconnect the cable between the main and ps boards? This is the first test for any Samsung TV.

[neilc6]

Re: UN55MU7500fxza Samsung Curve, Dead no picture

Sorry didn't see you did the backlight test already. Did you check the 13V with the main to ps cable disconnected? Second test is to power up the TV with one ribbon connected at a time between the tcon and the panel. Not sure if your model has a tcon board since you didn't include a pic of the entire back of the TV.

[R_J]

Re: UN55MU7500fxza Samsung Curve, Dead no picture

I see you did change the main board, It looks like the main board has the t-con built in, Try disconnecting the ribbon(s) (with power disconected) that go to the panel, it could be a bad panel causing the shutdown. Turn it on with the main to power cable disconnected so the backlights come on, then check the for the 13 volts, also with the backlights on see if you can see any lcd panel damage, but it could be that the screen was cleaned and liquid may have damaged the panel circuit board/components.

[Plurxtc1]

Re: UN55MU7500fxza Samsung Curve, Dead no picture

Yeah, I came across 3 curve TVs that had the same issue. No I don't see any damage. I was just wondering if anyone actually attempt to troubleshoot the LCD panel driver. Yes disconnected eachside of the panel from the LVS cable to see if which panel is shorted. None would let the TV boot with the main board attached. Seems to only work with the ones that doesn't have a built T-Con into the mainboard.

[brucetv]

Re: UN55MU7500fxza Samsung Curve, Dead no picture

This is the result of Samsung Electronic failing to properly compensate Samsung Display for quality panels and now we are seeing alot of panel problems starting in 2017 MU Series. Samsung Display had to design a panel that only uses a power supply and a main board without a tcon board in between without enough research and development and this is the result. At the same time there was a shortage of quality MLCC's on the market so they had to buy whatever was available to keep their greedy production going. Alot of these subpar MLCC's were installed on the panel driver boards and are shorting prematurely. They are in parallel so it's a pain in the ass to trace the short as well as a pain in the ass resoldering them in. We see alot that will have 3 green boards and one blue board and the short is usually on the blue board. Samsung Display recently announced they will no longer make panels for Samsung Electronics by the end of 2020 so Samsung Electronics is back to begging Sharp to make panels for them after they blew them off a few years back. The thought of that just disgust's me to no end.

[nomoresonys]

Re: UN55MU7500fxza Samsung Curve, Dead no picture

Buy a samsung...our motto is "We've been cranking out junk for the last decade and the public still laps it up"