Re: 820-3115B fan spins but no chime and no display

Also worth to mention is that it makes single beep if turned on with RAM removed.

2012 Macbook Pro A1278, board number 820-3115-B, EMC 2554. 2.5GHz i5 CPU.

The macbook came dead on arrival. No visible signs of liquid damage, everything looks clean. Checking power rails I found missing PPBUS_G3H. The R7005 was bad, after I replaced it the board voltages came to norm (PPBUS is 12.53V, 3V42 is 3.447, all 5V and 3V3 rails present). The board charges the battery (light switches from green to orange).

When I connect charger the fan starts spinning (high speed without trackpad; normal speed if trackpad is connected). However the board does not chime and...

Re: Wifi problem MacBook Pro unibody mid 2012

Finally found and fixed. It was bad U7200 (TPS51125).

Re: Wifi problem MacBook Pro unibody mid 2012

Yet another 3115 board with the same problem. Did anyone fix this?

My board had L3508 (camera 5V coil) burned which caused a bit of burn damage to the board surface. I cleaned the damage and replaced the coil. The board boots now and camera is working fine.

However it only boots fine if wifi cable is disconnected. When cable is connected it boots but shuts down on the Mac OS login screen. If I try to boot from USB (holding Option key after post) it shuts down too; I guess because it activates wifi card immediately....