Question HDD Rescue [WD10EADS], before I do any irrecoverable mistakes

Apr 1, 2020
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Hi helpful people, I have a HDD that wouldn't spin up and it wouldn't be recognized when plugged in to PC. It's a WD Caviar Green packaged as External HDD 1TB.

I've done the following checks:
SATA/USB Converter: tried with other HDD so that's not problem, and used another SATA/USB Converter too same result.
Diodes: D1, D2, D3, D4 all not shorted
Motor: all 4 contacts are shorted to each other (I'm guessing there was no burnt coil then?)
J6: bottom two pins not giving any voltages upon powering up, and top two pins giving constant low voltage, i cross-checked with WD10EZED, and eventually the replacement PCB that I got, that wasn't supposed to be the case, the pins should have fluctuating voltages upon startup.
Hence, I'm guessing that this is a PCB fault.

I've ordered for the PCB number 2060-701640-007 REV A, however there are a few differences which i will type out as below, original first, replacement second:
U12: Winbond 25X20ALNIG; can't see but shouldn't be Winbond
U2: EtronTech EM6AA160TSA-5G(O027G11AOA404.117N); hynix007E-A C HY5DU121622DTP-D43
C17: not available; available
U22: not available; available
SK3: not available; available
SK4: not available; available
Images (Left Original, Right Replacement) : PCB Comparison Rear; PCB Comparison Front

I've done the swaps for ROM/BIOS even before realizing the differences between the PCB's, and upon swapping U12, I've realised that my continuity test on the pins are shorted pin 8 and pin 7 which are inherently shorted on both PCB's, pin 8&7 short-circuited with less than 50 Ohms with pin 6, similarly pin 6 and pin 3 short-circuited for less than 50 ohms. I was worried that powering up the board would damage the ROM/BIOS and completely destroyed the chance of recovering this HDD.

However, I woke up today and test after almost 6 hours later, pin 8&7 no longer short-circuited with pin 6, similarly no continuity observed between pin 6 and pin 3. Instead, pin 8&7 has 9.5MOhm observed with pin 6, and 0.58MOhm observed between pin 6 and pin 3. I'm not sure why but it changed this morning.

My question then:
1) does serial number (sticker on the back of PCB) matter or just the PCB number alone will suffice for matching replacement?
2) difference in components on both PCB boards are fine too?
3) I know that U12 is the ROM/BIOS, but does it tie to the pre-amp/header and thus without U12, platters swap would still be okay for data recovery eventually?

Thanks very much for your help, HDD recovery services are rather limited in my region of residence and hence I'm DIY-ing this.
 
Apr 1, 2020
2
0
10
Stickers at the bottom of the PCB:
Original: 2061-701640-707 01PD4 XC A156 01VJL 0004350 0354;
Replacement: 2061-701640-X07 02PD4 XF AN18 7B62 C 0003390 0393