Question PCB swap on HDD Hitachi 320Go

Jul 11, 2019
Hi everyone! :)

If somebody could give me some advice, it would be great!
Here's my problem [please excuse my english, it's not my native language] :

My HDD no longer starts, no sound at all, not recognized. PCB may be the reason. I want to try to swap a functional PCB ("donor") to the dead PCB ("patient").

Model is : Hitachi 3.5" SATA 320Go
Ref : HDT721032SLA360
Manufactured date : June 2009

Front label mentions :
P/N : 0A38018
S/N : MC35NM8B
MLC : BA3120

PCB mentions :
Board : 110 0A90158 01
Main Chip: 0A58786
Motor Chip: 0A56511
Sticker Number : 0A29989 BA3129
/!\ There is one 8-pins chip in location "U5" labelled "93G86WP B916G". The location "U7" is empty. No firmware chip with a number starting with 25. /!\

Questions :
Which specifications and numbers (on PCB from donor) are mandatory to match in order for the HDD (mechanic from patient + PCB from donor) to work?

2. I read that most HDD made before 2010 don't need some BIOS transplant or some soldering ? Is it possible that a simple PCB swap may work ?

3. Is there some risk to do this kind of swap ? My HDD with data to recover (mechanic from patient) could be definitively bricked ?

Thank you very much for your precious answers! (y)
U5 is the "NVRAM" chip. It must be transferred from patient to donor.

The "ROM" code is embedded within the MCU (Main Chip: 0A58786). You need to match the code in this chip between patient and donor.

Note: U7 would normally contain the ROM code in those cases where the MCU is not internally programmed.

If you have a multimeter, measure the voltages at L300, L310 (near motor controller) and Q2 (near SATA power connector).
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