Short pins Seagate ST4000DM004 - 100815595

[Spinal]

Hello. To access the terminal i need to make a short pins in this PCB, but i don't know which ones exactly.

Attachments

[fzabkar]

What voltages do you measure between ground and each of the 4 HDA pads when the PCB is on and off the drive?

[Spinal]

What voltages do you measure between ground and each of the 4 HDA pads when the PCB is on and off the drive?

PCB is off the drive

A1 = 1.37V ; B1 = 0.68V
A2 = 1.37V ; B2 = 1.02V
A3 = 0.03V ; B3 = 3.22V
A4 = 0.03V ; B4 = 0V
A5 = 0V ; B5 = 1.76V
A6 = 5.18V ; B6 = 0V
A7 = 0V ; B7 = 0V
------------- ; B8 = 0V
------------- ; B9 = 0V

PCB is on the drive

A1 = 1.75V ; B1 = 6.04V
A2 = 1.75V ; B2 = 6.00V
A3 = 0.98V ; B3 = 2.23V
A4 = 0.98V ; B4 = 1.51V
A5 = 0V ; B5 = 1.76V
A6 = 5.18V ; B6 = 0V
A7 = 2.96V ; B7 = 0V
------------- ; B8 = 1.76V
------------- ; B9 = 0.03V

Attachments

[fzabkar]

The write channel would be driven by the MCU whereas the read channel would be driven by the preamp. Therefore, I believe that A3/A4 is the read channel pair (because it sits at 0.03V when the preamp is not connected).

[Spinal]

The write channel would be driven by the MCU whereas the read channel would be driven by the preamp. Therefore, I believe that A3/A4 is the read channel pair (because it sits at 0.03V when the preamp is not connected).

Thanks for your reply, I'll try.