MRT USB to SATA probe board cap removal

[lcoughey]

While my experience has been great with these boards and not having to remove the caps from the original USB board, there have been a few times when that isn't the case. Until now, I haven't documented which drives need it, but figure it is better late than never. That said, it is also possible that the need for the cap removal is more about the overall health of the board than it is with the model. I'm sure that will come to light as we collaborate and document together.

Model: WD40NDZW-11A8JS1
SN: WXF2E
FW: 01.01.A01
Capacity: 4TB
Bahavior before cap removal: would ID and read slowly, but the drive would go unresponsive before the utility could fully load. Couldn't get SA access. Mirroring kept quitting after a few seconds.
Behavior after cap removal: loaded utility without issue, saved SA resources, drive now imaging at full speeds where there are no head/media damage zones

[fzabkar]

AIUI, your PCB is 2060-810035.

Here are two photos:

https://www.zeroalpha.com.au/images/RTF ... 810035.jpg
https://recuperodatos.com/sites/default ... 26-PCB.jpg

The first has a JMicron JMS579 bridge while the second has an Asmedia ASM1151W. These two bridges appear to be pin compatible.

Attached is the datasheet for a JMS578 bridge. This appears to be pin compatible with the JMS579 and ASM1151W bridges. Pin #38 is an active low Reset* input. If this pin is grounded, then the bridge IC will be "quiet". The datasheet states that "an external RC should be connected to this pin". Therefore, you should look for a Resistor and Capacitor that are connected to this pin. The capacitor will be grounded while the resistor will be connected to a positive supply.

In short, you can disable the bridge by shorting its Reset input to ground. This is electrically safe. Typically, when an MCU is reset, all its GPIO pins become high impedance (hi-Z). I don't know if this also applies to the SATA Tx/Rx pairs.

Edit:

If point "X" is connected to pin #38, then it can be shorted to the adjacent ground plane.

[fzabkar]

A photo of this area on a 2060-800069 PCB confirms the connections to pin #38. Shorting point X to ground should keep the bridge in a reset state.

If this works, then you might want to ask MRT to add a switched, grounded pogo-pin for point X.

[fzabkar]

I suspect that these are the corresponding points for a 2060-800041 PCB. This PCB sometimes has a JMS569 bridge (https://www.zeroalpha.com.au/images/RTF ... ert-2.webp).

[fzabkar]

This is my guess as to the test point (X) for the Reset* pin on a 2060-800067 PCB. A point-to-point continuity test with a multimeter should confirm or reject my hypothesis.

[fzabkar]

This is my guess as to the test point (X) for the Reset* pin on a 2060-810003 PCB. The bridge is an Asmedia ASM225CM.