INSIGNIA NS-L47Q09-10A dropped now black screen

[jason424]

I received a INSIGNIA NS-L47Q09-10A with no picture. It was dropped by the former owner. I get the light on the front to light up red when plugged in and turns blue when hitting the power button. No image at all when turn off the room lights and check the screen or check with flashlight.
I have replaced a capacitor on my old Vizio 47" so I'm fairly familiar with that and testing fuses etc. but I don't know where to start testing on each board (or what each is called for that matter).

[budm]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Can you hear anything rolling around inside the LCD panel? It will not be easy to flip the 47 panel around to see if you may have broken lamp inside.
Also look at the back side of the LCD panel in the dark room to see if you can see the backlights flash on for seconds or not.

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

When I picked up the tv and brought it home I heard nothing moving or rattling around.
And I didn't see any light looking at the back in a dark room besides the front red/blue and the red optical port light up.

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Also, here are the voltages for the CN903 plug when the TV is plugged in and turned on:
on/off: 3.1
DIM: 3.1
12v: 0
12v: 0
GND: ground
GND: ground
GND: ground
24v: 1.3
24v: 1.3
PS_ON: 4.0
5v: 5.0
5v: 5.0

I would think the 12v's should have some voltage?!?

[stj]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

check the power board for cracks around all the screwholes and for cracked soldering on everything large or heavy.

[budm]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Beside looking for cracks on the board (you should remove the board from the chassis for close inspection, you should also
check the DCV between the two legs of the main filter caps to see what you have.

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Voltage with tv plugged in and on:
C907: 171.2
C908: 170.5
I'll remove the board after work for closer inspection.

[budm]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

The PFC Voltage booster (the DCV should be closed to 400VDC range) is not working, the 12V/24V SMPS runs on the boosted Voltage, so you need check that PFC section out first.

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Can you expand on what the PFC section is and how to test please? Beyond knowing what fuses and capacitors are, I'm clueless.

[freakaftr8]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Here's a thought why don't you unplug the inverter from the power supply and try to repower check boosted voltages then. I once had an instance where there was a cracked CCFL tube in a Samsung 40 inch that kept the boost circuit from powering up from a direct short

[budm]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Looking at pic #1 on post 1, it looks like he has both POWER cables, lamps cables, etc to the inverter board disconnected. OP did not explain why they are like that.

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

I had unplugged the inverter board cables as I was looking at that board for damage on the underside. I had plugged it back in completely before running voltage tests above.
And to verify, I had checked the voltage of the 2 large black caps (upper left of board) in my 2nd photo. I assumed these were the "main filter caps" that were referred to?

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Here's a thought why don't you unplug the inverter from the power supply and try to repower check boosted voltages then. I once had an instance where there was a cracked CCFL tube in a Samsung 40 inch that kept the boost circuit from powering up from a direct short

That would mean to unplug the 2 connectors (in the upper right of pic 4) coming from the power supply board, correct? And the boosted voltages were what I checked at the 2 big black caps?

[budm]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

'And the boosted voltages were what I checked at the 2 big black caps?'
Yes, those two large black caps (they are connected in parallel) laying its side are the main filer caps which should have close to 400VDC when the TV is turned on, but the PFC is not working right now so you are seeing only 160~170VDC.

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

I unplugged the 2 power connectors leading to the inverter board and the voltage tests the same at the 2 large caps.
I didn't see any cracks in the board or loose heavy parts where solder would have come free. I did notice some black stuff (like comes out of the top of caps) looking like it was coming out the green fuse(?) in the pic. I ohm'd it out and got 8.0 with it installed. Not sure if I should remove to test or what it should read.

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Oh and what's the best way to de-energize a board ⚡️

[stj]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

that's flux or glue

[stj]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Oh and what's the best way to de-energize a board ⚡️

cut the power,
and meter the large caps - the voltage should slowly drop till it's down to nothing.

[jason424]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

Is there any instruction that I can review on how to test the PFC section? I'd rather try to isolate part needed and replace than replace whole board.

[budm]

Re: INSIGNIA NS-L47Q09-10A dropped now black screen

IC901 is the PFC Controller IC, you need to get the P/N so you can get the pinout to find out if you do have VCC feeding the IC or not, also look real close at that section for any damages.