820 2879 b green light no fan spin

[Modder1]

Got myself a water damaged 820 2879
green light and no fan spin.
ppbus_g3h =12.59
pp3v42=present
pin 14 u7000 3.24 smc_bc_acok
3.34v pp3v3_s5
not sure if any of those measurements help.
kind regards

 

[dukefawks]

Resistance to GND on 3V42 rail and on RTC Xtal pins?

 

[Modder1]

19.1Kohm resistance to GND on 3V42
2.6Mohm resistance to GND on pin 1 R2810

 

[larossmann]

That's probably a bad MCP89. You can buy a replacement but half of them will be worse than the one that you have.

 

[dukefawks]

Did you short the power pads on the board, these do not auto turn on.

 

[Modder1]

if shorting power pads = pin 5 of J5713 to GND then the fan spins for a short time. I am not holding wire for more than a few seconds.
Holding it for longer seems to kick the fan into high. I also do not have the board in the body at this time. I am unsure if this makes any difference.

 

[Repairable]

out of body is no problem,

hook up the speakers, the plugin charger, then short pins 5 see if you hear a chime. or if you hook up a mouse if the light turns on on the mouse

See if you hear a chime is for the deaf people sorry for that, listen if you hear a chime.. gosh i am a dick

 

[dukefawks]

Usually that indicates a sense resistor issue. Resistance between U7000 pins 17/18 and 27/28?

 

[Modder1]

3.22 Ohm between 17/18 U7000
20.49 Ohm between 27/28 U7000

 

[dukefawks]

That seems fine.
See if all rails come high during power up. I bet one is missing.