[SOLVED] 820-2327 all rails good but no chime, no video MCP79 issue

[Crizz]

I'm trying to fix a 820-2327 which had a little bit water damage:
https://www.rossmanngroup.com/boards...t-water-damage

The board is now clean and I managed to reveal all the Power rails!
The fan spins normally and the DVD-drive makes noises at startup.
Both the CPU and GPU get voltage and become hot.
But there is no chime wether is a picture. Connected USB devices don't turn on.

Without Ram there is no beeping but the DVD-drive doesn't make noises anymore

I know the first hinds will be "look if there's anywhere else corrosion" but I'm pretty sure I fixed all missing components and broken traces ( it was pain in da aaasss!)

Is the ̶p̶̶c̶̶h̶ MCP faulty?

 

[aprendiz]

There is no PCH on this board, I guess you mean MCP..... Measure resistance to GND on L6995, resistance should be about 40Kohm, also measure resistance on Y2810 pins 1 and 4, resistance should be about 1Mohm.... There is a high chance of a bad MCP.....

 

[dukefawks]

I am sorry but looking at the picture of that board it was trash before you started with it. There is a corroded trace or resistor somewhere, I doubt this is worth the effort. There is no way to diagnose this

 

[larossmann]

Firstly, this is complete garbage. Don't even try,

If you really want to try, fucked up traces by U6100 are the most often overlooked by people I've had come for tutoring in the past on the 2327/2530. Re-check that?

But seriously, throw this shit away...

 

[Crizz]

No Title

YES I ment MCP
The board is now clean and charges the battery, ONE-Wire circuit works.

Traces by SPIROM U6100 look good

Resistance to GND on L6995 is only 15K
Resistance Y2810 Pin1 and 4 is open line

 

[Crizz]

As I aspected there was corrosion under the MCP. I reflow the chip and tadaaaaaaa machine works again !
Thank you all for your hints!
That was a good challenge for the weekend.
Seeing back I wouldn't do it again. I had to sacrifice almost a hole donor board and I had to fix over 30 traces ...

 

[larossmann]

Good job! Now good luck selling this working for over $100. but good practice nevertheless, and a good effort!