Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting TVs and Video Sources
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 12-07-2021, 11:44 AM   #21
dskall
Badcaps Veteran
 
dskall's Avatar
 
Join Date: Oct 2016
City & State: Bakersfield ca.
My Country: usa
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 2,802
Default Re: TCL 75R615 has sound, no backlight

Need the part numbers to know the gate, source and drain. Many videos on how to test.
__________________
I assume no responsibility for any stupid suggestions I might post.
dskall is offline   Reply With Quote
Old 12-07-2021, 01:44 PM   #22
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 8,146
Default Re: TCL 75R615 has sound, no backlight

Quote:
Originally Posted by thetonywarren View Post
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.
R_J is offline   Reply With Quote
Old 12-07-2021, 08:07 PM   #23
thetonywarren
Senior Member
 
thetonywarren's Avatar
 
Join Date: Feb 2013
City & State: Green Bay, Wi.
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 113
Default Re: TCL 75R615 has sound, no backlight

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
Attached Images
File Type: jpg PXL_20211208_015811842.jpg (572.3 KB, 12 views)
thetonywarren is offline   Reply With Quote
Old 12-08-2021, 08:35 AM   #24
thetonywarren
Senior Member
 
thetonywarren's Avatar
 
Join Date: Feb 2013
City & State: Green Bay, Wi.
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 113
Default Re: TCL 75R615 has sound, no backlight

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!!!
thetonywarren is offline   Reply With Quote
Old 12-08-2021, 08:54 AM   #25
vinceroger69
Badcaps Veteran
 
Join Date: Mar 2012
City & State: Nuneaton Warwickshire
My Country: uk
I'm a: Hobbyist Tech
Posts: 6,402
Default Re: TCL 75R615 has sound, no backlight

Quote:
Originally Posted by thetonywarren View Post
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
vinceroger69 is offline   Reply With Quote
Old 12-08-2021, 10:26 AM   #26
dskall
Badcaps Veteran
 
dskall's Avatar
 
Join Date: Oct 2016
City & State: Bakersfield ca.
My Country: usa
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 2,802
Default Re: TCL 75R615 has sound, no backlight

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.

Last edited by dskall; 12-08-2021 at 10:42 AM..
dskall is offline   Reply With Quote
Old 12-09-2021, 08:30 AM   #27
thetonywarren
Senior Member
 
thetonywarren's Avatar
 
Join Date: Feb 2013
City & State: Green Bay, Wi.
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 113
Default Re: TCL 75R615 has sound, no backlight

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 is offline   Reply With Quote
Old 12-09-2021, 10:06 PM   #28
thetonywarren
Senior Member
 
thetonywarren's Avatar
 
Join Date: Feb 2013
City & State: Green Bay, Wi.
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 113
Default Re: TCL 75R615 has sound, no backlight

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.
Attached Images
File Type: jpg PXL_20211209_234708301.jpg (560.1 KB, 10 views)
thetonywarren is offline   Reply With Quote
Old 12-09-2021, 11:58 PM   #29
dskall
Badcaps Veteran
 
dskall's Avatar
 
Join Date: Oct 2016
City & State: Bakersfield ca.
My Country: usa
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 2,802
Default Re: TCL 75R615 has sound, no backlight

Thanks for feedback.
dskall is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2022
Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 10:38 PM.
Did you find this forum helpful?