Samsung UN58J5190 - Doesn't Power on and has Standby

[Chris24]

Hey everyone - I have a Samsung UN58J5190 with these symptoms: Does not power on, has standby light, standby light blinks 5 times after pressing "power on." When plugged in the power supply is making a very faint ticking sound, and this goes away when pressing power on.

Following instructions from the great team here in recent posts for Samsung with similar symptoms, I did the following tests:

I tested with mainboard disconnected from power supply - backlights do not come on (symptoms no change/5 red blinks)

I tested with T-Con disconnected from one side at at time, and completely from MB (all separately) and backlights do not come on (symptoms no change/5 red blinks)

Multimeter:
Power Supply to Main Board:
Plugged in and power off > to power on:

A13V 1 : 11.6 > 12.8
A13V 3 : 11.6 > 12.8
A13V 5 : 11.6 > 12.8
A13V 7 : 11.6 > 12.8
GND 9 : 0.0

OD-UD 2 : 2.31 > 2.31
BLU-PWM 4 : 3.26 > 3.26
PWR ON/OFF 6 : 3.90 > 3.90
GND 8 : 0.0
GND 10 : 0.0

Power Supply to LED
plugged in to > press power on:

9 D2-: 00.1>0.36
8 D2-: 00.1>0.34
7 NC:
6 S+: 00.1 > 00.1
5 NC:
4 S-: 00.1 > 00.1
3 NC
2 D1+: 188.6 > 324~344~352 (repeating back to 324 and up to 352)
1 D1+: 188.6 > 323~348~354 (also repeating)

Pics to follow and as always - appreciate the help

[Chris24]

Re: Samsung UN58J5190 - Doesn't Power on and has Standby

Pics attached - I hope its not another backlight....

[neilc6]

Re: Samsung UN58J5190 - Doesn't Power on and has Standby

This model likely has the same failures as UN58H5202AF, bad backlights that damage your power supply. On the UN58H502, one FET typically shorts. Until you test and replace your backlights, you can't start troubleshooting the power supply. Would check the FETs and diodes in the backlight driver section for shorts.

https://techhometravel.com/un58h5202...oesnt-turn-on/

[Storyteller12]

Re: Samsung UN58J5190 - Doesn't Power on and has Standby

+1

this model likely has the same failures as un58h5202af, bad backlights that damage your power supply. On the un58h502, one fet typically shorts. Until you test and replace your backlights, you can't start troubleshooting the power supply. Would check the fets and diodes in the backlight driver section for shorts.

https://techhometravel.com/un58h5202...oesnt-turn-on/

[Chris24]

Re: Samsung UN58J5190 - Doesn't Power on and has Standby

Thanks guys, I’ll test out the LED driver side and the LEDs next. Appreciate the video - although I am getting power where he was not, I will look for a short elsewhere.

Would you rule out or have tips to check the MB?

[neilc6]

Re: Samsung UN58J5190 - Doesn't Power on and has Standby

The main board sends two signals to control the backlights. A logic BL-ON signal to turn them on and a PWM signal to dim them. Samsungs have pull up resistors on the BL-ON and PS-ON signals so when you unplug the cable to the main board, it forces the power supply and backlight on. If you don't have backlights, you need to resolve that issue first.

[Chris24]

Re: Samsung UN58J5190 - Doesn't Power on and has Standby

Thanks Neil - that makes sense. I didn't find any bad FETs or Diodes on the PS LED driver area or elsewhere, however with the LED tester I only got ~95V on one side (42 lights) of the LED wire and no response from the other side (or 302V my tester max). Ordered a new set of lights and will take her apart. Will report what I find out. Thanks

[neilc6]

Re: Samsung UN58J5190 - Doesn't Power on and has Standby

It looks like one string failed open circuit which will act like a fuse and may have protected the power supply. With your LED tester, you can power the one good string independent of the power supply and turn on the TV to see if you have video.

[Chris24]

Re: Samsung UN58J5190 - Doesn't Power on and has Standby

Opened her up and multiple LEDs are out, including one complete set. New sets came in from eBay and replaced all the strands and now the TV works. Turned down the backlights immediately 😀 Glad the power supply was protected.

Thanks for the help and feedback Neil, and the link to the video which I used to to confirm your points and test/fix the TV.