broken dahua with wrong 12V...

[frank10]

I'm not familiar with Linux at all.
I can try something on Windows, I also have Arduino Mega, I don't know if its serial ports can be used to RX TX to Dahua UART? (definitely that 4 holes are for UART)
Also I have never tried these things before, I think I need your help
BTW, this Dahua is a 4421r-as with chinese firmware.

Anyway, I tried to reset it, but the IR doesn't light up after pressing the reset button for more than 10s... Could it be because it's bricked and so it needs the UART/TFTP recover, or even if bricked, it should resets itself and light the IR?
Maybe TFTP is easier/faster to do? I mean to see if it communicates something? Or should it really be used the UART way?

 

[cor35vet]

you should stop looking into software faults for what is clearly a hardware oops
The IR light will turn on if you power up the camera, yours is not turning on, something is kill.

 

[frank10]

Well, I thought that, before this crash, I disabled the IR to always off, from software menu. Now I thought, if bricked, maybe it can't get the reset command... so it remains with the IR off.

Anyway if it's only a HW issue, this IR thing means it's not only the Ethernet chip broken, but something different, right?

 

[cor35vet]

You don't know which IC supplies the electronics on board with power.
A good start would be to measure the 3.3V pin on the serial connector to see if it is powered when you plug the camera in (PoE or 12V tail plug).

 

[tangent]

I'm not sure I'd bother but I'd start with a pair of these: High quality Tweezers Smart SMD RC Resistance Capacitance Diode Meter Tester LCD Multimeter MS8910,3000 counts Auto Rang/ Scan-in Multimeters from Home Improvement on Aliexpress.com | Alibaba Group
and test/measure some of the diodes, caps, and resistors around the power supply.

 

[frank10]

No, it says 0.1V/0.3V on the 2 pins starting on left or right side
I have a good multimeter for diodes/ resistors/ caps; also an ESR for caps. Now, I will try something at random...

 

[frank10]

So, I looked at diodes on rear: B240A, M4 and 2xHD06 rectifier: all seem fine (they show 0,6V only on one side) apart the B240A that gives 0,2V on one side (they are shottky should be normal).
Apart only one B240A, the one downside in the middle of the 2 6R8: this gives 0,2 on one side, but 1,2V on the other side...
The big caps on the front have the correct capacitance.

I don't know what are those P-88 5ejxy (2 pin) and those LD5JI: (there are many)
And what is that big BGG 5fhu8 near the rectifier. Also those 2 pieces near it that don't have any signs, anyway I tried to test like a diode those 2 and they gave 0,6V on only one side...

 

[VorlonFrog]

The only reason I suggested checking for console output is to help confirm/deny that the processor is receiving any power and operating. Like the others said, if the power chip is toast, it's not very likely anything on the board at all is working.

 

[frank10]

Yes, but it's not off completely: I remind it consumes 2W...

 

[frank10]

Oh, my... I just retested the Wattmeter: now is definitely 0W!