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 07-20-2021, 10:55 PM   #1
Tech06
New Member
 
Join Date: Oct 2018
City & State: Missouri
My Country: United States
I'm a: Knowledge Seeker
Posts: 9
Default TCL 55S401LHAA No Power

This TV was Brought to me in non working condition. There are no power\standby lights on the set at all. Here is what I have done so far.

1. Took back off of the tv and tested that the system was getting AC voltage at the plug.
2. Tested the fuse on the power board.
3. Tested the DC voltage at the Large Capacitor.(170Vdc)
4. Checked for any obvious burn marks bad solder joints.
5. Unplugged various devices from the main board.(Tcon, Wi-fi module,)

I'm not getting any response from the set at all. When I measure voltage between the Main Board and the Power Board I am only seeing between .1-.23 vdc on some of the pins. That seems low to me.

Any Ideas? Thanks in Advance.
Attached Images
File Type: jpeg image0.jpeg (135.7 KB, 9 views)
File Type: jpeg image1.jpeg (128.2 KB, 9 views)
File Type: jpeg image2.jpeg (137.8 KB, 21 views)
File Type: jpeg image3.jpeg (146.5 KB, 9 views)
File Type: jpeg image4.jpeg (178.8 KB, 19 views)
File Type: jpeg image5.jpeg (93.7 KB, 7 views)
File Type: jpeg image6.jpeg (76.0 KB, 3 views)
Tech06 is offline   Reply With Quote
Old 07-21-2021, 01:12 AM   #2
lotas
Badcaps Veteran
 
Join Date: Jan 2016
City & State: Sochi
My Country: russia
I'm a: Knowledge Seeker
Posts: 870
Default Re: TCL 55S401LHAA No Power

Power Supply TCL 01-L14TH4-PWB
Attached Files
File Type: pdf Power Supply TCL 01-L14TH4-PWB.pdf (110.7 KB, 19 views)
lotas is offline   Reply With Quote
Old 07-23-2021, 03:12 PM   #3
RDC55
Senior Member
 
Join Date: Dec 2017
City & State: JACKSONVILLE
My Country: United States
I'm a: Knowledge Seeker
Posts: 156
Default Re: TCL 55S401LHAA No Power

Try posting the actual voltage measurements at the P2 connector on the Power Supply with the TV powered up. You need to label the pins as to nomenclature and pin number - unfortunately TCL seems to like to make it hard and put the pin assignments on the back of the boards.
RDC55 is offline   Reply With Quote
Old 07-25-2021, 04:24 PM   #4
Tech06
New Member
 
Join Date: Oct 2018
City & State: Missouri
My Country: United States
I'm a: Knowledge Seeker
Posts: 9
Default Re: TCL 55S401LHAA No Power

Quote:
Originally Posted by lotas View Post
Power Supply TCL 01-L14TH4-PWB
lotas, Thanks for the schematic. You wouldn't happen to have the entire Service Manual would you?
Tech06 is offline   Reply With Quote
Old 07-25-2021, 04:24 PM   #5
Tech06
New Member
 
Join Date: Oct 2018
City & State: Missouri
My Country: United States
I'm a: Knowledge Seeker
Posts: 9
Default Re: TCL 55S401LHAA No Power

Quote:
Originally Posted by RDC55 View Post
Try posting the actual voltage measurements at the P2 connector on the Power Supply with the TV powered up. You need to label the pins as to nomenclature and pin number - unfortunately TCL seems to like to make it hard and put the pin assignments on the back of the boards.
With my meter set on 20vdc. I show no voltages on the P2 connector at all.
Tech06 is offline   Reply With Quote
Old 07-26-2021, 10:21 AM   #6
RDC55
Senior Member
 
Join Date: Dec 2017
City & State: JACKSONVILLE
My Country: United States
I'm a: Knowledge Seeker
Posts: 156
Default Re: TCL 55S401LHAA No Power

I believe even with the Power Supply disconnected from the Main you should still be making 12VDC. The PFC will be about 170 VDC until the main is connected and then it should be about 390 VDC any time the TV is plugged in.

So I would say time to troubleshoot the Power Supply or find a replacement if it is not making 12 VDC with it disconnected from the Main.
RDC55 is offline   Reply With Quote
Old 05-21-2022, 02:02 PM   #7
Tech06
New Member
 
Join Date: Oct 2018
City & State: Missouri
My Country: United States
I'm a: Knowledge Seeker
Posts: 9
Default Re: TCL 55S401LHAA No Power

So to update this. I did end up replacing the power supply a quite a few months back. The power supply was the issue at the time. It lasted less than a year. I now have the set back again this time with a different issue. The unit powers on and I can hear the system click through the menus but, now the backlight is not coming on at all. I thought there may have been a bad safety resistor but, after replacing that I still have no backlight on the set. I think I should just replace the thing at this point.
Tech06 is offline   Reply With Quote
Old 05-21-2022, 02:31 PM   #8
neilc6
Badcaps Veteran
 
Join Date: Nov 2015
City & State: BC
My Country: Canada
I'm a: Knowledge Seeker
Posts: 1,379
Default Re: TCL 55S401LHAA No Power

TCLs have lots of backlight failures. Only 2 or 3 rows of LEDs on a TV that size. Panel may also be taped down making the replacement more difficult.
neilc6 is offline   Reply With Quote
Old 05-21-2022, 02:50 PM   #9
nomoresonys
Badcaps Veteran
 
Join Date: Jan 2013
City & State: midwest
My Country: U.S.
I'm a: Knowledge Seeker
Posts: 8,188
Default Re: TCL 55S401LHAA No Power

guess you were too busy to report back that a new powerboard fixed the tv. PASS.
nomoresonys 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 01:40 AM.
Did you find this forum helpful?