I’m trying to repair a Toshiba MK5075GSX HDD. The board details are:

Board Number: G002825A
Problem: No Life Signs or Spin -> The 5V fuse was blown.

What I’ve Done So Far:
I bypassed the fuse by soldering a wire.
I supplied 5V with a current-limited lab power supply to prevent further damage and monitored the board for heat.
The Winbond Cache Chip (photo attached) started producing significant heat.
My Question:
Is it possible to purchase a donor board and simply transfer the "BIOS" chip from the damaged board to the donor board like here described:https://www.hddzone.com/blog/fix-toshiba-mk5075gsx-pcb-board-g002825a/ ?

Will I be able to read the data from the HDD afterward?
Do I also need to transfer any other chips from the damaged board (e.g., the Winbond Cache)?

and another one:
IS it possible that some devices only have 5V input?
The 12v and 3.3V seems not to have any connection anywhere.

Thanks in advance for your insights! I appreciate all opinions and advice.

These boards have no real protection. The 5V supply goes to the motor controller IC (TLS2...), and this IC then powers the spindle motor and voice coil. It also produces the lower voltages for the MCU, SDRAM and SPI flash memory (aka "ROM").

The fact that the SDRAM cache is heating up means that the 5V supply has punched through the 3.3V (?) regulator and is supplying the full 5V to the IC. Hopefully the ROM has not been similarly affected.

Try a ROM transfer, but first read the ROM in a chip reader if you can. This chip is critical and must NOT be damaged.

_________________
A backup a day keeps DR away.

Hello,

you mean the chip which is Marked as Bios chip? I tried to read with T866ii but get ID error. Maybe i have to Buy a socket. (I wired it manually 1To1 on ).


or is there another Rom. I have to correct me here. I confused the cache chip with the other one. I marked the one that gets hot again.

Thanks for your effort!

IC602 is the "ROM". Measure the resistance between its VCC and GND pins.

I suspect that the overvoltage killed this chip.

_________________
A backup a day keeps DR away.

Hello,

i measured IC602 VCC to GND and get about 350 Ohms. A also checked the other pins for short to Ground. Nothing unusual here.
So this should be good i think?

Maybe i have a problem with reading the Chip soldered to the board and should remove from Board bevor Reading?

The patient PCB is probably unsalvageable, so why not cut the PCB trace going to the Vcc pin?

_________________
A backup a day keeps DR away.

Hello,
i have cut the Trace on PCb and i also have to correct me on VCC to gnd i get 366KOhms
Is this a good result?

Thanks!

You should now be able to read the device in-circuit.

_________________
A backup a day keeps DR away.

Hello,

I was able to read the BIOS chip today. Fortunately, I also received the donor board today.
As suggested, I made a backup and then transferred the chip to the donor board. Now the hard drive works.

Thank you so much for the advice and support fzabkar!