insignia ns50d40 dead

[ogtommy]

Re: insignia ns50d40 dead

This is the best i got until my wife brings home slr from work. Any part not clear/ blurry ill redo
Thnx again

[ogtommy]

Re: insignia ns50d40 dead

missed the point about the - side of the main filter cap. thanx for the heads up

[ogtommy]

Re: insignia ns50d40 dead

ok my OCD is kicking in so i retested from the - of the ripple cap to the diode and got 295v.
zds1 cathode 22v
zds11 cathode 1.8v
safety resistor 0.045v

[budm]

Re: insignia ns50d40 dead

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

We need to find out if we do have VCC to run the SMPS IC for the switched 12V/LED power supply or not, you will have to work on the board with bottom side up and all connected and running, it will be very dangerous.
We need to get the specification sheet of the SMPS IC UM1 first so we can find out which pin is the VCC pin, so look at the print on top of the IC and then look for the spec sheet.
Pictures provided by shopjimmy.

[budm]

Re: insignia ns50d40 dead

ok my OCD is kicking in so i retested from the - of the ripple cap to the diode and got 295v.
zds1 cathode 22v
zds11 cathode 1.8v
safety resistor 0.045v

No need to mess with that 5VSTBY section, it is working otherwise you will not have the 5V per your report.

[ogtommy]

Re: insignia ns50d40 dead

http://pdf1.alldatasheet.com/datashe.../SSC9522S.html
this is what i found. so from pin 2 vcc to pin 4 gnd there was 0volts. also went from pin 2 to pin10 (control ground) 0v. also tried - on filter cap to vcc once again 0 v.

[ogtommy]

Re: insignia ns50d40 dead

btw those are some really nice pics off shopjimmy you found!! ive been trying for 30 minutes to take clear pics on my s8 and always some dark blurry spots!!

[budm]

Re: insignia ns50d40 dead

You are testing it with all the boards connected and the PS-ON is present, right?

[ogtommy]

Re: insignia ns50d40 dead

yes. ac plug in wall, connector to logic board plugged in, connector to led board in. dim dim red light on. stby 5v present etc etc

[budm]

Re: insignia ns50d40 dead

OK, the next hard part is to locate the switched transistor that is turned on the PS-ON signal so it will supply the VCC to that SMPS IC.
Board tracing will be required at this point by tracing back from the VCC pin to see where it goes to.

[ogtommy]

Re: insignia ns50d40 dead

so i traced it to a cap and a zero shunt resistor to a transitor. one side to ts1 and the other to optocoupler um4
let me know if i did it right or if i should take it further
tommy

[budm]

Re: insignia ns50d40 dead

I did not have a chance to trace the board yet, but the typical set up is the PS-ON will turn on a transistor that drive the LED side of the OPTO, the Photo transistor in the OPTO is then turned on, that photo transistor then will provide the current path to bias on the switched Transistor to allow the rectified Voltage from the Aux winding of the 5VSTBY transformer to run the SMPS IC. So one pin (Emitter or the Collector) of the transistor (it can be either PNP or NPN) should have 15~20V all the time and when the bias is applied to turn on the Transistor then you should have the Voltage on the Emitter or the Collector.
So just check the E-B junction Voltage (around 0.6~0.7V) to see if it is present or not when PS-ON is present.

[ogtommy]

Re: insignia ns50d40 dead

so heres something weird. I was going to start tracing the other side of optocouplers and check voltages when i realized pushing the connector to logic board in on an angle turned on all the powersupplies. as soon as i put the rest of the connector in (the gnd pins) the tv/baclight turned off. i also started probing on the logic board side to make sure there wasn't a fused or broken via for the ground plane when i noticed the main ic on the logic board was HOT!! without a heatsink that has to be wrong. so it seems like the logic board has crapped out in my humble opinion. i design pc boards for stm32 microcontrollers and i have had the same exact situation multiple times. overcurrent blew the internal ldo of the microcontroller (or an analog signal pin) and fused it shut so it has a direct path to ground. I think im going to call this logic board shot and possibly convince my sister who has the same exact tv dissasemble hers and borrow her logic board.
budm, thanks for the help and relayer too. i appreciate all the effort you guys put in.
ill hopefully post a picture of a working tv later tonight
tommy

[ogtommy]

Re: insignia ns50d40 dead

It works!!!

[ogtommy]

Re: insignia ns50d40 dead

now to find this board for less than the price of a used tv, and then to repair the 3rd and remaining monitor i blew

[budm]

Re: insignia ns50d40 dead

It works!!!

What did you find?

[ogtommy]

Re: insignia ns50d40 dead

so i took my sisters logic board out of her tv since she's working nights and tried it in my tv. the tv turned on and worked like a charm. the original logic board seems to have shorted out when the hdmi cable ground was shorted with 120vac live current. the tell tale was the logic board ic burning up so i figured it was kapoot. plus the powersupply board was turning on backlight and 12v sound when i removed the gnd connection from the logic board. when i connected ground all went off. the only signal that was never there was the 0V on the poweron pin(pin3 i believe). i tested them now after i put them in and there was power on all pins except pin3 which was 0v(shorted to ground to power on my tv). i am so glad to have a working tv. 1 goes out its ok but to loose 3 tvs in 1 second really really sucked. i rewrote the edid on my samsung 27" monitor so that works and replaced the internal board of the other one because it was too much work. lol
thanks for all the help
tommy

[ivtec]

Re: insignia ns50d40 dead

so i took my sisters logic board out of her tv since she's working nights and tried it in my tv. the tv turned on and worked like a charm. the original logic board seems to have shorted out when the hdmi cable ground was shorted with 120vac live current. the tell tale was the logic board ic burning up so i figured it was kapoot. plus the powersupply board was turning on backlight and 12v sound when i removed the gnd connection from the logic board. when i connected ground all went off. the only signal that was never there was the 0V on the poweron pin(pin3 i believe). i tested them now after i put them in and there was power on all pins except pin3 which was 0v(shorted to ground to power on my tv). i am so glad to have a working tv. 1 goes out its ok but to loose 3 tvs in 1 second really really sucked. i rewrote the edid on my samsung 27" monitor so that works and replaced the internal board of the other one because it was too much work. lol
thanks for all the help
tommy

May not be your case but many people also don't know just by plugging and unplugging the HDMI cable from the TV input with TV on may burn the HDMI output,i've see that.