Insignia NS-55D420NA16 Backlight Problem

[budm]

Re: Insignia NS-55D420NA16 Backlight Problem

Take the Voltage reading using the your LED tester when you have new LED strips installed so we can see what the total Vf of the LED string is.
So you have lots of shorted out LED's.

[Stu71584]

Re: Insignia NS-55D420NA16 Backlight Problem

Ok so I replaced the LED strips and tested them with my tester and they all light up. I reassembled the filters and the panel and tried testing it and now I get no picture or backlight whatsoever. I checked for voltage on the led connector from the power supply board and there is no voltage there. At one point in my testing I touched something on the power supply board and got shocked. I'm wondering if I somehow damaged it. Any thoughts before I replace the board?

[Stu71584]

Re: Insignia NS-55D420NA16 Backlight Problem

Ok update. So I got everything to power up but unfortunately I think I damaged the panel itself during the process. I'm posting a picture so one of you can confirm my diagnosis. So close!

[attainteddragon]

Re: Insignia NS-55D420NA16 Backlight Problem

yeah rather broken.

[mmartell]

Re: Insignia NS-55D420NA16 Backlight Problem

I might need the strips from this. Let me know if you're selling.

[Stu71584]

Re: Insignia NS-55D420NA16 Backlight Problem

I might need the strips from this. Let me know if you're selling.

sure shoot me a message if you want them...

[Andrew F. Ali]

Re: Insignia NS-55D420NA16 Backlight Problem

Shit happens. Even to some of us who should know better. Don't worry as this exercise is not a total loss. You learnt a few things in the process. Cheer up.

[Betviper]

Re: Insignia NS-55D420NA16 Backlight Problem

**First post** Man that sucks. I have the exact same TV but when I check my red/white wires going to the LEDs I get a spike of a little over 400DCV then back to almost 0DCV. I am trying to remember if that was across the red/white or red only and to chassis for ground. (it's been a few weeks) My backlights do not even flicker. With the red/white wires unplugged I get 0DCV on both pins. My voltages on my 10 pin output are the same as yours. Not sure if I should order the LED tester or if it is the LED driver on the powerboard. Anyone have any suggestions for a newbie? Thanks

[angelos]

Re: Insignia NS-55D420NA16 Backlight Problem

When measuring the LED voltage you put your black probe on Chassis earth and measure on the RED wire (Anode). According to what i read on this post the voltage should be around 200VDC. You probably have an "open" LED and that's why the voltage spikes at 400V.
Take great care when opening the panel as to not break the screen. My experience is almost every time i had a problem like this it turned out to be backlight LED's that had failed.

[Betviper]

Re: Insignia NS-55D420NA16 Backlight Problem

Awesome. I was measuring everything using black to chassis for ground. The LED output I wasn't seeing anything so I tried across the red/white. Thank you for the advice. I have an LED tester on the way. I will report back what I find. This is an awesome site!

[Betviper]

Re: Insignia NS-55D420NA16 Backlight Problem

Question. The LED tester says 0-300V. Will that still work for my LEDs since I'm getting a 400V spike? Just not sure howmany LEDs are on my TV. I guess I should just pull the screen because if there are some LEDs out I will need to replace them anyway. With them all exposed I could test each strip individually.

[budm]

Re: Insignia NS-55D420NA16 Backlight Problem

Question. The LED tester says 0-300V. Will that still work for my LEDs since I'm getting a 400V spike? Just not sure howmany LEDs are on my TV. I guess I should just pull the screen because if there are some LEDs out I will need to replace them anyway. With them all exposed I could test each strip individually.

It went over 400V because the LED power supply is not seeing the load, the normal output Voltage is 200V @400mA as printed on the board.
https://www.badcaps.net/forum/attach...7&d=1529354494

[budm]

Re: Insignia NS-55D420NA16 Backlight Problem

Question. The LED tester says 0-300V. Will that still work for my LEDs since I'm getting a 400V spike? Just not sure howmany LEDs are on my TV. I guess I should just pull the screen because if there are some LEDs out I will need to replace them anyway. With them all exposed I could test each strip individually.

What is the LCD panel model number as printed on the sticker to the LCD panel?

[Betviper]

Re: Insignia NS-55D420NA16 Backlight Problem

Man!! Yall Rock!! I will check the model number and post it when I get home feom work. Thank you!

[Betviper]

Re: Insignia NS-55D420NA16 Backlight Problem

OK. I never got around to getting you the model number budm and I do apologize, but my LED tester arrived today and I went ahead and got down to the LEDs. 11 strips of 6 LEDs total. I have 6 strips each with 1 LED not working in the strip. 1 strip with 2 LEDs not working and 1 strip that none of the 6 will light up. Should I replace all 11 strips or just one strip and the other individual LED that are not working? Should I be able to test the strips with an Ohm meter to see a short?

[Betviper]

Re: Insignia NS-55D420NA16 Backlight Problem

Ok. Well this repair was short lived. I just cracked the screen. Arghhhhhhhhhh!!! Little mistakes can sure make a person feel pretty stupid. I was hoping to learn from the original poster. Oh well. Thanks for the advice! I enjoyed tinkering with it and learning though.

[Wilderone]

Re: Insignia NS-55D420NA16 Backlight Problem

Ok. Well this repair was short lived. I just cracked the screen. Arghhhhhhhhhh!!! Little mistakes can sure make a person feel pretty stupid. I was hoping to learn from the original poster. Oh well. Thanks for the advice! I enjoyed tinkering with it and learning though.

Sorry to hear, I've only cracked one but l learnt my lesson to take my time & keep to the same process.
I recently bought a couple of suction cups for larger panels but I find I'm using them everytime now & allows you to lift them evenly.

Chin up there will be another one...

[Betviper]

Re: Insignia NS-55D420NA16 Backlight Problem

I used suction cups and had no issue taking it off or putting it back on. I was putting it back on until I ordered the new LEDs and I was ready to put them in. I didnt want to leave it all taken apart. It was one of the metal tabs on the side of the TV. Does the screen fit inbetween those tabs? If so it's like the screen grew 1/4 of an inch. It wouldn't go between them so I figured the screen laid on top. Then putting the clips on the side it cracked. I'm still irritated about it though. I was $35 away from having it fixed and would have been a perfect TV for my shop. poof

[Wilderone]

Re: Insignia NS-55D420NA16 Backlight Problem

I used suction cups and had no issue taking it off or putting it back on. I was putting it back on until I ordered the new LEDs and I was ready to put them in. I didnt want to leave it all taken apart. It was one of the metal tabs on the side of the TV. Does the screen fit inbetween those tabs? If so it's like the screen grew 1/4 of an inch. It wouldn't go between them so I figured the screen laid on top. Then putting the clips on the side it cracked. I'm still irritated about it though. I was $35 away from having it fixed and would have been a perfect TV for my shop. poof

I find sometimes there is flex in the chassis & plastic panel runners, especially if moved around while the panel is out.
When it comes to this stuff & the more complex strip downs I take a quick photo at each stage to refer back to.
Helps if you have to leave it apart for days & weeks.

[zape]

Re: Insignia NS-55D420NA16 Backlight Problem

I'm going to replace the strips on this TV
I see here people damage the screen while trying to do this.
Any advice on how to properly do this and not damage the screen?
Should I use suction cups?