ST9250315AS PCB Burnt

[Miftah]

Hi,

Today i have a burned Seagate PCB, are this TVS diode ? the drive won't turn on, nothing sign of life.

PCB No. 100536286 Rev B

Is there any chances to repair the board ? or maybe some of measurement test, since i don't have the circuit schematic.

Thanks

Attachments

[fzabkar]

Today i have a burned Seagate PCB, are this TVS diode ?

Yes.

Is there any chances to repair the board ? or maybe some of measurement test

Yes.

[fzabkar]

Here is a detailed photo of the 5V TVS diode:
https://forum.hddguru.com/download/file ... &mode=view

Measure the voltages at V1 and V2. These should be the Vcore and Vio test points.

Attachments

[Miftah]

Hi fzabkar,

Lot of thanks, i would try it then.

Could you please tell me how many volts are V1 and V2 ?

Should i test with powered line ? If yes, then which is safe, onboard or offboard ?

Many thaanks.

[fzabkar]

Test with power. Use a screw hole as your ground reference.

V1 and V2 will probably be around 1.2V and 2.5V (or 3.3V).

Test the PCB off the drive.

[Miftah]

Nicely noted, i will post the result

[Miftah]

Fazbkar,

There are no voltage both V1 and V2, please help me for further.

Thank you.

[Miftah]

Only a resistor marked "R499" have 3,3volts

[Miftah]

Only a resistor marked "R499" have 3,3volts

Sorry, "R499" giving 2.5 volts, and the motor connector giving 4.2volts, a small 5 leg component loks like voltage regulator giving 3.3volts.

[fzabkar]

ICBW, but IMHO that 5-pin component looks too "busy" to be an LDO regulator. Normally an LDO regulator would have two filter capacitors on its Vin and Vout pins, but there don't seem to any nearby. Can you identify the markings on this chip?

Maybe we can work backwards. Pin 1 of the SDRAM should connect to the 2.5V supply. With the power removed from the PCB, can you measure any continuity between pin #1 of the SDRAM and either of the two "2.2" coils (V1 and V2)? Similarly, can you measure any continuity between pin #8 of the "BIOS IC" and either of the two "2.2" coils?

BTW, I believe the R499 resistor may the current sense resistor for the voice coil or spindle motor.

[Miftah]

ICBW, but IMHO that 5-pin component looks too "busy" to be an LDO regulator. Normally an LDO regulator would have two filter capacitors on its Vin and Vout pins, but there don't seem to any nearby. Can you identify the markings on this chip?

# The mark like R81, i can't clearly identify.

Maybe we can work backwards. Pin 1 of the SDRAM should connect to the 2.5V supply. With the power removed from the PCB, can you measure any continuity between pin #1 of the SDRAM and either of the two "2.2" coils (V1 and V2)?

# It's 0 ohm, continue beep on multimeter, good continuity both V1/V2 - Pin 1 SDRAM (Winbond W9464G6IH-5).

Similarly, can you measure any continuity between pin #8 of the "BIOS IC" and either of the two "2.2" coils?

# It's 0 ohm, continue beep on multimeter, good continuity both V1/V2 - Pin 8 BIOS (Winbond 25X40AL09).

[Miftah]

Both coil are missing the power, maybe we can trace from here.

[Miftah]

Further inspection, there are a circuit shorted by kind of a deep cut, please take a look at the pict.

Attachments

[fzabkar]

I don't know what to make of the cut to those traces. If the tracks are severed, then maybe the PCB isn't economically salvageable.

As for V1 and V2, your measurements would suggest that they are shorted together, or that both are shorted to ground. Could you perform the same measurements on the 200 ohms range? Could you also test the resistance between ground and each of V1 and V2?

[Miftah]

I don't know what to make of the cut to those traces. If the tracks are severed, then maybe the PCB isn't economically salvageable.

# i'm thinking about PCB swap, would it need EEPROM/BIOS swap also ?

As for V1 and V2, your measurements would suggest that they are shorted together, or that both are shorted to ground. Could you perform the same measurements on the 200 ohms range? Could you also test the resistance between ground and each of V1 and V2?

# Yes, it's shorted with ground

[fzabkar]

# i'm thinking about PCB swap, would it need EEPROM/BIOS swap also ?

Yes.

http://search.store.yahoo.net/yhst-1443 ... 7584971410

[Miftah]

PCB swap with ROM Chip transfer fix the drive.

Thanks a lot fzabkar, attempting to backup the data now.