WD50NDZM-59PW8S1 intermittent access

[Lardman]

This came in with pcb damage (chunk missing) and I've had to swap the MCU onto a donor.

I'm getting intermittent access and more clicking than I'd like. I though it might be a heads issue at first but swapping over to a donor PCB everything sounds great UA access is constant but it's obviously encrypted.

Switch back to the pcb with patient MCU. Clicking is back access and UA intermittent.

The transplant looks fine at least the outside row that I can see. When it's working the critical modules all pass a check and I was able to get a full backup.

Before I pull the MCU and reball anyone have any suggestions ?


Techno mode key
Techno mode key......................... : Ok


HDD Status sector....................... : Ok

RAM:
System controller (SoC)................. : 88i1047F0 0x(5450)
HDD Info reading........................ : Ok
Heads number............................ : 10
Cyl Count............................... : 384

ROM:
Read ROM................................ : Ok
ROM Data size........................... : 512 Kb
Flash ROM dir reading................... : Ok
Flash ROM dir reading (Ext)............. : Ok (Active)
Modules directory address............... : 809 011
SA regions address...................... : by default
SA regions address (RAM)................ : by default
Module 02 access........................ : Granted

SA SPT.................................. : 2140

SA Translator loading................... : Ok
SA defects assigned..................... : 3

ROM Modules:
ROM version............................. : 00.0JT
ROM F/W version......................... : 0000000J
Overlay F/W version..................... : 00.0KT
Servo F/W version....................... : 0A.08

Heads configuration..................... : by map
Heads number............................ : 10
Heads number in use..................... : 10
Switched off heads...................... : No
Heads map............................... : 0,1,2,3,4,5,6,7,8,9

Relocations............................. : 0 (2 442)

Service area:
Power up log reading.................... : Ok
Dir data................................ : Yes
Permanent overlay....................... : Yes
CFG data................................ : No
SA dir reading (ID)..................... : Ok
Dir items loaded........................ : 648

SA Access............................... : Copy 0,Copy 1

Configuration reading................... : Ok
CFG tech mode lock...................... : No
Self encryption drive................... : Yes
SED Info read........................... : Ok
Master Password......................... : Yes
User Password........................... : No
SED tech mode lock...................... : No
UA writing.............................. : Granted

[Lardman]

Anyone seeing the same my issue was the PCB. After a couple of reballs not fixing things, I tired another couple of donor board and finally found 1 that worked. 2 heads are a little weak but everything is reading fine. Careful where you source your donors or at least check them prior to use.

[fzabkar]

Interesting. I wonder if the supply rails are wonky, as was the case with those old WD PCBs with "head mimic" faults. Or could the HDA connector be the problem?

[Lardman]

I've not had time for a post mortem on the pcbs yet, I just want to get this case off the bench at the moment. It's another 810012, I never did get to the bottom of the odd behaviour of the last troublesome one either. They're paper thin pcbs and prone to warping when heated so I wouldn't be surprised if that's a factor.