Help: Which chip on PCB is Firmware chip?

[ndzeel]

I got a replacement PCB for Hitachi HD and now need to move the firmware chip from the damaged board to the replacement PCB. Is the firmware chip U6 or U3? I've attached a photo of the PCB.

If you can help many many THANKS!!!

Attachments

[GreyDKang]

Both chips are firmware. U3 chip is often not as MCU also has it.
Usually enough move only U6.

[fzabkar]

U3 is a serial flash memory.

I can't see its markings, but I believe U6 is the "NVRAM".

BTW, are you aware that there is a fuse, F1, and TVS diode, D1, near the SATA power conector?

Littelfuse Surface Mount Fuses, N = 2A, S = 4A:
http://www.farnell.com/datasheets/48294.pdf

[ndzeel]

No I wasn't are there is a fuse, F1, and TVS diode, D1, near the SATA power conector

Can they be changed? If yes how or who can do it?

Thanks so much for your help.

[fzabkar]

Test them first. Set your multimeter on the 200 ohms range. The fuse should measure close to 0 ohms, while the diode should overrange.

Your local TV/AV repair shop should be able to do the soldering for you, but let's see some measurements first.

[ndzeel]

fzabkar,

Thanks again for the help I'll get them tested, if I need to replace them do you know where I can buy replacements?

Your assistance is really appreciated!!

[fzabkar]

The fuse should be available from Mouser or Digikey in the USA, and Farnell in Europe. I can't see the marking on D1, but I expect it would also be available from those same sources.

That said, if there is no other fault, then you can remove D1 and flow a blob of solder over F1. However, by doing this you will have removed the drive's overvoltage protection, so be absolutely certain your power supply is OK.

[ndzeel]

Thanks again for your help.

Update - I tested the fuse, F1 (S), and the TVS diode, D1 (5). The fuse is dead and the TVS diode is fine so I now need to order a fuse and have it put on.


If the fuse is removed and not replaced will the PCB work without it??


Thank You!!!

[networks]

If you have a multimeter that can check DC current then put it across the fuse and power up the drive and monitor the current usage and be quick to remove power if it goes past 4amps that will confirm if the drive will run. You have to have the fuse in place to complete the circuit. The fuse is to protect the circuit from overload.