820-00840 no SSD

[Kyle93]

Arrived without SSD showing up in disk utility and question mark folder. U8640 was missing along with R8640. Replaced U8640 and R8640 but still no SSD shows up.

Also tried known good SSD.

U8640 area looks good. L8600/02 look good as well.

PP1V8_S5G is 1.8V

What to try next??

 

[Kyle93]

Replies from my post here have disappeared.

I know we left off to where I was getting proper voltages and resistance to ground was low on some components that needed to be.

What else should be checked?

 

[2informaticos]

Looks like someone else messed up with SSD area before.
You must check all series caps from data lines and pull-up resistors.
Also check for broken traces.

 

[Kyle93]

U5420 pin 6 is only 0.197V Is this correct?

 

[2informaticos]

The voltage there is proportional with SSD consumption, sensed at R5420.
So yes, will be very low if SSD doesn't work.

 

[Kyle93]

Could this be bad CPU? SSD_BOOT_CONN_L starts at 1.8V then drops to .286V however SSD_PWR_EN_CONN_L is 0V

SSD_PWR_EN_L is 0v and comes from the CPU?

 

[2informaticos]

I think there are two kinds of SSD for this slot, but not compatible.
Did you try an SSD from same board model?

 

[Kyle93]

No we do not have a donar machine. Arrived with a 256GB 656-0067 C0882730 drive and trying to replace with a 128GB 656-0066a C0881870 drive.