Samsung Odyssey G9 (c49g95tssr) no picture or backlight. Power LED shows

[grimreaper420]

Then you need to check the signal lines at the HDMI and DP inputs for resistance relative to ground, if you connected it “hot”, that is, the monitor was connected to the network and the source too, and when connecting the connecting cable, a discharge could occur and then the processor would die, or maybe there was lightning ...

Ah okay! How do I know which lines at the ports are signal lines? Are the pins layouts on all HDMI and DP ports the same?

[grimreaper420]

Then you need to check the signal lines at the HDMI and DP inputs for resistance relative to ground, if you connected it “hot”, that is, the monitor was connected to the network and the source too, and when connecting the connecting cable, a discharge could occur and then the processor would die, or maybe there was lightning ...

I tested the pins anyway (on the HDMI port) and my results were pin 1 - OL, pin 2 - 1.1, pin 3 - OL, pin 4 OL, pin 5 1.1, pin 6 OL, pin 7 OL, pin 8 1.1, pin 9 OL, pin 10 OL, pin 11- 1.2, pin 12 OL, pin 13 OL, pin 14 OL, pin 15 61.7, pin 16 61.1, pin 17 12.23, pin 18 14.71 and pin 19 OL

[lotas]

These are the ones that go straight into the 8+2 processor.

[grimreaper420]

they were quite difficult to test but ive got a few results from them

(going from left to right from the picture you attached)
61.6, 61.7

OL, OL, OL, OL, OL, OL, OL, OL

220, 245

58, 58, 57, 57, 57, 57, 57, 57

247, 247, 57, 57, 57, 57, 57, 57, 57, 57

[lotas]

I don't understand your numbers, there shouldn't be low (not some Om) resistance on these lines relative to ground, they usually show as a diode when changing multimeter probes...
57 is this Om, kOm, mOm?

It's easy to check there, they are all connected to resistors.

[grimreaper420]

I don't understand your numbers, there shouldn't be low (not some Om) resistance on these lines relative to ground, they usually show as a diode when changing multimeter probes...

ah i think i tested wrong. i tested for continuity in manual mode and not 'diode' mode. i will retry in diode setting

[grimreaper420]

I don't understand your numbers, there shouldn't be low (not some Om) resistance on these lines relative to ground, they usually show as a diode when changing multimeter probes...
57 is this Om, kOm, mOm?

It's easy to check there, they are all connected to resistors.

okay, in diode continuity mode i got the readings

1.755v, OL, OL, OL, OL, OL, OL, OL, OL, OL

1.563v, OL, OL, OL, OL, OL, OL, OL, OL, OL

1.564v, OL, OL, OL, OL, OL, OL, OL, OL, OL

does that make sense?

[lotas]

Yes, nothing criminal is visible, rather the ports are all alive, all that remains is to find out what caused the fuses to blow in the LED driver...

[grimreaper420]

Yes, nothing criminal is visible, rather the ports are all alive, all that remains is to find out what caused the fuses to blow in the LED driver...

guess thats good news so far

I was retesting the mosfet and capacitor this morning, and they looked okay. i turned over the board to check whats on the other side, and i found this mosfet (has code 1E on it) directly below. I tested and got the results gate (black probe) to source (red probe) i got .OL but in reverse gate (red) to source(black) i got 0.673v. source (black) to drain (red) i got .OL drain (black) to source (red) i got 2.184v.

[lotas]

1E - (sot23 package) is a BC847A NPN transistor.

[grimreaper420]

1E - (sot23 package) is a BC847A NPN transistor.

Ah okay! I retested with multimeter in diode mode
Base (red probe) to Emitter (black probe) - 0.674v
Base (red probe) to Collector (black probe - 0.667v
Base (black probe) to Emitter (red probe) - .OL
Base (black probe) to Collector (red probe) - .OL
Collector (red probe) to Emitter (black probe) - .OL

That looks okay. Next step to remove mosfets and retest?

[lotas]

Do you have low resistance relative to ground at point A? Take a clear photo of this area.

[grimreaper420]

Do you have low resistance relative to ground at point A? Take a clear photo of this area.

okay something weird happened. i retested point A on the blown fuses and they both tested 23.1Ohms (like before). retested points B, but B.1 is now showing 15 - 17Ohms (changes every time i retest it, jumps between 10 - 15) and B.2 16.9 - 17.7 (wont stay in on one number). Point C is jumping between 16.9 - 17.5.

[lotas]

It's strange, maybe at that time they measured it and there was poor contact between the probes and the contacts, the fuses seemed to have blown?

[grimreaper420]

It's strange, maybe at that time they measured it and there was poor contact between the probes and the contacts, the fuses seemed to have blown?

Maybe, i usually check a few times before i write my numbers down. The fuse is definitely blown, in continuity mode there is no beep and OL on both of them. i checked with another fuse further up the board and that one beeps.

[grimreaper420]

It's strange, maybe at that time they measured it and there was poor contact between the probes and the contacts, the fuses seemed to have blown?

this is the other side of the board. the red circle highlights the area of where the blown fuses are

[lotas]

Here the board is multi-layered, there may be 3 or 4 layers and it's hard to determine which tracks go where...

[grimreaper420]

Here the board is multi-layered, there may be 3 or 4 layers and it's hard to determine which tracks go where...

I'm not sure I'm testing the mosfet correctly. do you know the best way to test it?

[grimreaper420]

Here the board is multi-layered, there may be 3 or 4 layers and it's hard to determine which tracks go where...

i tested the 2 mosfets when the power was plugged in. both of the drains had 19v, the gate on both of them were 9v. does that give any clues?

[lotas]

I already wrote that the mosfet should not have a short circuit between the legs...
Do you have a laboratory power supply and a thermal imager to determine the heating location?