Help - Momentus 5400.6 ST9320325AS dead

[cyberkid]

Hi,
It's from a Freeagent Go portable. I left PC on for overnight downloads with portable hdd. at morning the PC was on standby mode and the HDD LED was off. there was a burning smell through the USB port on the casing. removed the casing and connected it to an external USB->SATA connector, the drive was spinning, but not at the full speed. It wasn't getting detected in BIOS too. again connected it to the original casing, the LED's were blinking on and off.
now it's not at all spinning up.
there are no visible damages on PCB. is it a PCB damage? how can I confirm it?
Any help is greatly appreciated.

Specs:
Seagate Momentus 5400.6 320GB
ST9320325AS
FW: 0001BSM1
PCB : 100536286 RevB

Thanking you in advance.
Vipin.

Attachments

[fzabkar]

There appears to be a protection diode to the right of the SATA power connector in the third photo. There also appear to be three inductors or low-ohm resistors in series with each of the 5V supply pins.

Can you zoom up on the abovementioned components?

If your board can't be repaired, then you will need to transfer the 8-pin serial EEPROM chip in your first photo, from patient to donor. This chip stores unique, drive specific calibration data.

[cyberkid]

Meanwhile I went to local technician who does some occasional Data recovery. He says that it can be a PCB problem, and if I could find an exact model, he can try to recover data.
btw, there is a slight change in color on the first photo, is it normal?
More pictures http://img51.imageshack.us/g/p6020152.jpg/
Thank you very much.

Attachments

[fzabkar]

KEZ appears to be a 5V TVS diode. Can you measure its resistance on the 200 ohms range of a multimeter?

The other three parallel connected components appear to be filter capacitors, not inductors as I originally suspected.

[cyberkid]

It measures 0.8 ohms across KEZ.

[fzabkar]

The diode is a TVS (transient voltage suppression) diode. It sacrifices itself by going short circuit in order to protect the rest of the electronics. The solution is to remove the shorted diode by desoldering it, or by snipping its pins close to its body with flush cutters. Just be sure your PSU is OK, as you will no longer have any overvoltage protection.

I can't offer any suggestion for a replacement diode, at least not in an smt package. However, you could use a leaded version, say a P6KE6.8A, and solder it directly across the SATA power pins. Connect the cathode (striped end) to pins 7, 8, and 9, and connect the anode to pins 4, 5, and 6.

http://www.littelfuse.com/data/en/Data_ ... evised.pdf

http://pinouts.ru/Power/sata-power_pinout.shtml

[cyberkid]

How can we do a successful PCB swap? I will get a matching PCB (100536286 RevB) soon.
any steps other than swapping 8 pin BIOS rom chip from old board to donor board? precautions?
Thank you.

[fzabkar]

Assuming there is no other damage, a ROM swap should work. If you are not experienced at soldering, then ask your local TV/AV repair shop, or practice on some junk boards. I believe your board may be a little on the delicate side.

BTW, am I right in assuming that removing the TVS diode didn't bring the board back to life?

[cyberkid]

sorry for my vague reply.
TVS diode was broken. got it bypassed with a good PSU by an electronic technician. but it didn't bring the board back to life. a part of the PCB was overheating without the metal head assembly being connected.
he checked the original board and said that chip controlling the motor is gone.
Got a donor PCB with matching Rev. No.
Done the PCB swap with BIOS rom chip . but, the motor was not powering up.
there is no voltage coming at the terminals to drive the motor.
The motor is showing enough resistance when checked with a multimeter, which avoids any chances of shorting in the winding.
It is getting detected as a "USB device" in device manager.
the LED on the casing flashes at first, then sleeps, and then flashes continuously.
how should I proceed?
please help me.
Thank you.

[fzabkar]

I would confirm that both +5V and +12V are present at the drive's SATA power connector. You state that the "PCB was overheating", so I assume they should be OK.

I would then test for the Vcore (1.2V) and Vio (2.5V or 3.3V ?) voltages on the PCB. The two 2.2uH coils (near the motor controller) should be convenient test points, as would the jumper pins, and the supply pins at the EEPROM and RAM. You could do these tests with the board disconnected from the drive.

If all the above are OK, then I would try to connect to the drive's serial terminal interface. If the serial EEPROM has failed, then hopefully the MCU will report the failure as a checksum error or something similar.

[cyberkid]

Thank you for your replies.
+5V and +12V are at the drive's SATA power connector - confirmed
the Vcore (1.2V) and Vio (2.5V or 3.3V ?) voltages on the PCB - on the original PCB it failed. with donor PCB it's ok.
chip controlling the motor on original PCB was damaged - confirmed.
technician suspects a jammed motor bearing, but he is not a DR guy. so he seeks the support of this forum to confirm it.
any particular tools to unlock it?

[poehere]

NO. You need the knowledge to do this one. We are not going to tell you how to unstick a motor on your drive and screw it up more. This takes a lot of time and knowledge to understand how to do this one. It is one thing to mess with your PCB board but when you open your drive it is another story on this one. If you do not have a clean room and the proper tools to do this one with then you will destroy it for sure

[fzabkar]

Customer support PC-3000
Seagate Barracuda IV: wedging bearing
http://www.acelab.ru/dep.pc/pc.tech.sup ... cuda4.html

English translation:
http://translate.google.com/translate?h ... cuda4.html

Otherwise, if your drive has a stiction problem then see this thread, but heed the warnings:
http://forums.seagate.com/t5/FreeAgent- ... 242#M11384