Chosen Solution
Hi, I have the above TV which will not power on… just has a blinking red LED! I’ve tested the outputs on the white 14 pin connector and they all seem ok. but ive noticed that a MOSFET under the heatsink is getting very hot!
Under this heatsink there is a MDF11N60TH…
So question time, is it a LED fault? A main board or power supply issue? If I unplug the main board i’ve read the LED backlight should come on, which it does not. Making me believe its LED or PSU. Does anyone have a guide on testing the LED backlight? Having unplugged the LED cable and testing Pin 1, which should be +255V, its wildly hunting about from 50V up to about 300V, all over the place! Any leads what I could be looking at to fix at component level, the SEM5025 LED driver? Thanks Onis Update (07/01/2019) Right following the DC power line to pin 1 of the white LED connector I’ve found two diodes that have a forward voltage of 0.5V and are leaking 2.0V in the other direction! So this could be part of the problem.
This is fed from pins 1 + 5 of the L9101 LED driver. so possible faulty LED driver? Or the voltage feeding that, it’s power is from the Vdrv rail. This Vdrv is from the transformer TM801S pins 7 + 9 which has 4 resistors that are metering quite a bit off of spec too…
@onis_uk yes, your backlight should come on. If it does not the issue is indeed your power board. Not sure how hot this IC gets. I am usually more worried about those staying cold when they are supposed to get hot. How hot is too hot? Anyhow, if in doubt you can of course replace it. A replacement part (STF10N60M2) is only a few $$ but will require soldering. You would need to get an LED tester to check the LED backlight array. Or take the complete panel apart and test the LED’s individually (very much a PITA and not efficient ;-) I have used freeze spray before to see if the component will then work. So see if that will make a difference.
