WD Green Data Recovery Part 1: PCB Analysis and Preamp Diagnosis
A 3.5-inch Western Digital Green drive arrives completely dead. This video walks through power draw testing, the difference between internal and external ROM chips, and how power monitoring pinpoints preamp failure without guesswork.
Power Draw Reveals the Problem
A healthy WD Green typically draws roughly 1.75 amps on the 12V rail at startup and settles to about 0.45 amps during idle operation. This drive pulled 2.5 amps. That five-fold spike indicates an electrical short somewhere, but not where. The short could be on the PCB, in the motor, or in the head stack assembly.
To isolate the source, the technician swaps in a known-good PCB from a matching WD Green donor (revision 2060-701537). The power draw stays at 2.5 amps. Since a good PCB did not fix it, the problem is inside the drive itself.
Internal ROM vs. External ROM
Examining the WD Green's PCB reveals no visible U12 chip. This is intentional; Western Digital stores ROM data (head adaptives, micro-jogs, preamp revision info) inside the MCU on many of their models instead of on a separate EPROM.
With an external ROM chip, a PCB failure is straightforward: desolder the chip, move it to a donor PCB, and the drive works. With internal ROM, the data must be rebuilt from the service area on the platters using professional software like PC-3000. That takes hours instead of minutes and is impossible with consumer tools, which cannot access the service area at all.
Diagnosing Preamp Failure
Power monitoring narrows it further. The current spike occurs specifically when the drive tries to access the service area, which requires the head stack assembly's preamp to power up. The current fluctuates erratically instead of following a smooth ramp. Multiple fuses and TVS diodes on the PCB are intact; the overcurrent bypassed all of them and went straight to the preamp.
The likely cause: a wrong power adapter (19V instead of 12V) or a power surge that overwhelmed the protection circuits. The preamp on the head stack assembly is destroyed, and the fix is a full head stack assembly replacement from a compatible donor with matched micro-jogs. That procedure is covered in Part 2.
Drive Drawing 5x Normal Current? We Can Read That Graph Too.
Our Austin lab has PC-3000 hardware, power monitoring tools, and donor WD Green drives. Free evaluation, no-data no-fee.