TCL 75R615 has sound, no backlight

[dskall]

Need the part numbers to know the gate, source and drain. Many videos on how to test.

[R_J]

Originally Posted by thetonywarren

Ok, does anyone have a good source for how I should be testing these particular mosfets? Ive viewed a few videos on youtube, but just looking for suggestions.....

Thanks!

If they don't check shorted, they are very likely ok. For a proper test you need to remove them and that could just cause more problems.

[thetonywarren]

Ok, so I removed the heatsink that attaches to the two mosfets, I understand this is probably overkill but I wanted to be as throrough as possible. Please see the attached picture with both of the mosfets, I believe thy are MDF18N50, also see the attached link with the data sheet for reference....

https://datasheetspdf.com/pdf/830304...hip/MDF18N50/1

I will attempt to test both of these components per this video......

https://youtu.be/gloikp9t2dA

[thetonywarren]

I am still struggling in testing out these two mosfets, Im unable to re-create the testing results using 3 different multimeters I have with diode mode......Im not sure if Im doing something wrong or if there's something specific about these components that would prevent me from using a standard inexpensive multimeter in diode mode to test......any help is much appreciated......

Thanks in advance!!!

[vinceroger69]

Originally Posted by thetonywarren

I am still struggling in testing out these two mosfets, Im unable to re-create the testing results using 3 different multimeters I have with diode mode......Im not sure if Im doing something wrong or if there's something specific about these components that would prevent me from using a standard inexpensive multimeter in diode mode to test......any help is much appreciated......

Thanks in advance!!!

I have one of these testers as i do find testing certain parts at times hard
https://www.ebay.co.uk/itm/143173138...YAAOSwPF9ci9rw

[dskall]

I maybe wrong here but I think your problem is that your gate to source is 10v to turn on mosfet. Your meter may not be able to do that.

[thetonywarren]

I kind of thought about that, even though I was not sure.....is it because my meter is powered with a 9v battery it doesnt have enough voltage to trigger the mosfet to turn on/off? I know that description is pretty crude/simple, just trying to understand the concepts.....If that's the case Im guessing i'd need a more powerful DMM or a bench type meter that plugs into the wall? Regardless, Im purchasing one of those cheap LCR tester meters on amazon to try and sort things out.....

[thetonywarren]

I replaced the cap as well as resoldering the heatsink and mosfets. I was too impatient to wait for the LCR meter to arrive. TV seems to power up normally!!! Great news. Thanks to all for the help and advice.

[dskall]

Thanks for feedback.