Insignia NS-50D40SNA14

[flibby3655]

Hello all,

TV works great for about a minute and a half, then the back lights turn off. The image is still there under a bright light.

I changed what caps I had on hand (black caps, greenish blue are original) the latter showed good ESR.

The chip labeled UL1 gets very hot after just a few seconds, and I suspect this is the problem area.

Which components near the device should I be looking at?

[budm]

Re: Insignia NS-50D40SNA14

P/N of that IC UL1?

[flibby3655]

Re: Insignia NS-50D40SNA14

Thanks Budm,

[budm]

Re: Insignia NS-50D40SNA14

OB3362: LED driver IC.
It is over heated is probably due to too much LED sink current flowing through the IC or something in the boost converter section of the IC.
I will not be surprised if one or both of the two LED strings have some shorted out LEDs.
You should also remove the LED connector, the one with RED/WHITE/BLUE/Black and then turn on the TV to see if it still get hot, it should not because it should go into shutdown due to no load.
You should also check the resistance between the chassis GND against each one of those 4 wires (connector not connected to the board) to see if we have any resistance reading, it should not have.

Insignia 19.50S12.001 Power Supply / LED Board
http://www.shopjimmy.com/insignia-19...led-board.htm#
Pictures provided by shopjimmy

[flibby3655]

Re: Insignia NS-50D40SNA14

Thanks budm,

Which direction does one go through to replace the LED's? Front or back?

I'm asking because I fix a ton of laptops and AIO PC's and would like to know in advance. Thanks!

[budm]

Re: Insignia NS-50D40SNA14

Did you do the test as suggested?
You have to remove everything from the front, 50" LCD glass is big so you have to be real careful.

[dick_barton]

Re: Insignia NS-50D40SNA14

The chip labeled UL1 gets very hot after just a few seconds, and I suspect this is the problem area.

What voltage do you have between pin 3 & 14?
Recommended voltage data sheet 6v - 30V

[flibby3655]

Re: Insignia NS-50D40SNA14

Thanks for the help everyone! I broke the screen. But did find two burned out LED's.

[vinceroger69]

Re: Insignia NS-50D40SNA14

Thanks for the help everyone! I broke the screen. But did find two burned out LED's.

Thats always the risk when removing any lcd panel maybe you can use the boards/good leds for future projects or sell them on etc

[dick_barton]

Re: Insignia NS-50D40SNA14

Sell on your parts and use the money towards a replacement set. You have the confidence that all but the screen and some of the leds are working. There is a market out there.

[DarrylF]

Re: Insignia NS-50D40SNA14

I have the same problem with the same model. IC chip UL1 does get very hot after about 3-5 minutes back light shuts off.Press power button to turn off and then press power button and back light comes on just briefly. I took a old aluminum heat sink and sort of attached it to the IC and TV ran for several hours and the heat sink just gets a bit warm. I see no dark areas on the picture when it is up and running. My thought is the current limiting resistors are to small of ohm value and can't restrict the current flow to the LED's. I just don't know which resistor or resistor bank is the problem. The heat sink works well, just need a way to permanently attach the heat sink.

[DarrylF]

Re: Insignia NS-50D40SNA14

I am thinking if I can get the schematic for the UL1 chip maybe I can increase the resistant value that supplies the chip. I saw on U tube whereas a person did replace a bank of resistors (total of 8 resistors) 2 each in series and 4 banks in parallel of total 8 resistors then through the board added one large say 2 watt (don't remember the ohm value). I hope it wasn't a fake post but who knows, there a lot of people out there smarter than me. I will research a lot more before I make a permanent fix and will let everyone know.

[budm]

Re: Insignia NS-50D40SNA14

The IC gets hot because you probably has some shorted out LEDs so the internal MOSFETs inside the IC will have to dissipate more heat due to more Vrops on the MOSFETs.
Per IC spec sheet, pin 5 is the LED current setting pin.

[DarrylF]

Re: Insignia NS-50D40SNA14

I am going to put the TV on our spare bed face down and take the back off and leave the screen and internal sheets of opaque panels alone right there. Pick up the back shell. Then going to plug in the board, turn it on and see if there are any bad LED's. I had it apart once before but lifted the screen and panels. To scary to do it that way again. I lost 2 other TV's chipping the LCD panels.

[DarrylF]

Re: Insignia NS-50D40SNA14

Budm, you are right !! One strip top right looking at panel has one LED out and 3rd row down right side has one LED out. Boy they are sure small LED's. I have a few laying around but not that small. I wish I had looked at this earlier as this is the 2nd tear down. Now to find these tiny LED's.

[DarrylF]

Re: Insignia NS-50D40SNA14

Any one have a part number for these LED's. Or maybe the whole strip. 4 LED's on a strip. LED is 3.12 mm Square.

[vinceroger69]

Re: Insignia NS-50D40SNA14

usually there is a part number printed on the led strips have you found any numbers on your strips?

[DarrylF]

Re: Insignia NS-50D40SNA14

I actually ordered a new /used power board on Ebay. Same discoloration on board under UL1 chip. At least the board works, mine, I short circuited. After ordering 2 LED strips and testing, all LED's are working now but after assembly, same problem. I know it is Micky Mouse but I took a cooling fan and heat sink, drilled thru power board (making sure no traces where I drilled). The heat sink came from a Video card and I did have to do modifications to the heat sink. Anchored the heat sink with fan on top of chip with the 2 plastic pins that anchored the heat sink on the video card. Applied heat sink compound before mounting the heat sink. Tied in the fan to a on/off 12 volt power source (CEM4 capacitor) and can now watch the TV for as long as I want.So far over 5 hours at a time. Heat sink gets slightly warm. Was going to use a 5 volt fan but all 5 volts on the board stay on all the time.