[SOLVED}820-3437 B-No image on screen, high fan spin & orange light on charger

[galvestonmac]

I just got in a MacBook Air Early-2014 820-3437 that powers on but goes to high RPM fan spin and the light on the charger goes to orange. This happens with AC power adapter and with battery.
No image/backlight on the screen, no chime. There was some corrosion at R8131. I cleaned it up and replaced it. There was also some corrosion at U3210. I cleaned it up and reflowed it.

SMC_ONOFF Measures 3.37v at R5115


Suggestion on where I should begin? Thanks!

 

[galvestonmac]

PPVCC_S0_CPU=1.68v

 

[dukefawks]

Orange light on charger is normal without battery. USB mouse lighting up when plugged in? Does it do the 3 times on/off thing before staying on?

 

[galvestonmac]

OK thanks. I will check out the mouse tomorrow. It starts up right away when the adapter and stays on until the power is unplugged. It doesn't turn on/off three times, it just turns on and the fan spins high RPM. Will get back with more info when I plug mouse into the USB port.

 

[galvestonmac]

Plugged in USB mouse and there is no light on either port

 

[dukefawks]

Any history on this machine, liquid? Having CPU Vcore and board not booting is not going to be fun

 

[galvestonmac]

User says that there was no liquid but there was some corrosion. I dropped it in the cleaning tank and cleaned it up thoroughly and when I put it back together it boots right up. USB mouse now has light. The only strange thing is that now it's doing the fan spin 3 times and then starts. What's that about? Other than that, seems to be working. I'm letting it run overnight on my bench with grapher to put it through a workout. Will let you know more! Thanks!

 

[dukefawks]

3 times on/off is normal for these.

 

[galvestonmac]

All working good so far except the battery is now not charging. Looking further into it. Turns out now that the customer tells me that the trackpad hasn't worked. Nothing like getting all of the info so you can actually try to fix the real issues. Will report back findings related to the no charge on the battery with readings.

 

[2andrewd]

There's a thermal sensor on trackpad.. If it's acting up and not communicating, the fan spins high.

- Disregard as inaccurate! (see below)

 

[dukefawks]

Thermal sensor is indépendant from trackpad. Cable is the first thing to check for corrosion.

Is the battery recognized in OSX? If PPBUS is at 8.6V without battery it is probably a dead battery.

 

[galvestonmac]

OK thanks for the info. Will check trackpad and cable tmrw.

 

[galvestonmac]

OK. I ended up replacing the trackpad and cable and along with the SMD work that I did the customer paid and picked up the laptop. Many thanks for your help on this forum!