820-00165 .290 A Fan Spin but no activity

[2click]

Hi, this computer arrived turning on but without video, it has all the power rails, it turns on and get to .290 A shuts down one time and goes again to .340 A. Has SUS voltages, no visible corrosion, all rails present what else to check?
SMC bypass only turns on when I remove my tweezers from R5116 (when holding for 10-15 seconds, it does nothing. Is this normal behavior?)

 

[2informaticos]

Any history fault available?

PLT_RESET_L comes high?
Did you try known good BIOS?

MacBook cannot turn on if SMC_ONOFF_L is maintained tied to ground.
The mentioned behavior is normal.
SMC bypass mode can be recognized because the fan must start with full speed.

 

[2click]

Tried known good BIOS, nothing
PLT_RESET_L not present, removed U1950 and found that PIN 8 was gone, so replaced U1950 and put a jumper from PIN 8 to c1950 PIN 1. Then found out that R1950 was missing... put a new resistor on R1950 place and did the trick, it is working now!
Thank you 2informaticos!

 

[Askaleto]

2click, you wrote in the beginning " computer arrived turning on but without video ". Did it make chime sound?

 

[2click]

No sound, it was doing nothing...

 

[Askaleto]

2click, I have the same motherboard with similar problem with PLT_RESET_L not present and PP3V3_S0 only 0.54V.
Can you please confirm me that there is actual R8162. It should be very next to R1950.
On my board, this resistor is missing.

 

[2informaticos]

Machine cannot chime, if PLT_RESET_L is missing.
PCH didn't received correct signal from pin 3/U1950 in his case.

U8160 and associated resistors are not place on the board.

 

[2click]

Did you make your board work? If you don´t have PP3V3_S0 you should definitely check that first... maybe you have a short on that line.

 

[Askaleto]

Did you make your board work? If you don´t have PP3V3_S0 you should definitely check that first... maybe you have a short on that line.

If this was a question for me, yes I made it work. I have soldered new U8030 which is TPS22924C load switch on PP3V3_S0. After that everything started to work fine. I have tested the laptop for about 2 hours when suddenly fan started running at full speed. It sems I had a bad luck and palm rest sensor faild. But Macs fan control applicatio in automatic mode on CPU senosor solved the fan noise. Laptop is worling without any delays and very responsive. The customer was happy to have his laptop fully functional again. So I consider this job done.