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 Post subject: Seagate st9160821as DEAD/No power/No signs of life
PostPosted: February 25th, 2018, 21:21 
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Location: Bristol, UK
This is the a sata hard drive that have come into my workshop this week and presents as "DEAD/no signs of life".

I need help in fixing the PCB of this hard drive. I will try to explain as much as I know and what I am trying to find out.

First..... The Backstory:
The customer is not sure what happened to this drive exactly, but when he went to use it, the drive was DEAD. It came to me in a usb caddy. When the caddy is plugged in the led lights but no sounds can be heard from the hard drive. I removed the drive from the caddy and plugged it in to a PC PSU, but still no sounds/signs of life could be heard. That's all I know / don't know:
---------------------------

Seagate st9160821as (160GB 2.5" HHD)
=========================
[Picture A]

PCB serial #: 100398689 REV C

Components Tested:
none yet

This PCB has very few reference designators.

Any ideas where I should start testing? I think I should definitely test components on the 5V circuit, as this drive has only been used in an usb caddy.

Should I be testing components on the 12v circuit too?

Thanks for any help you might give.


Attachments:
IMG_20180225_204943.jpg
IMG_20180225_204943.jpg [ 1.57 MiB | Viewed 3835 times ]
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IMG_20180225_201542.jpg [ 2.39 MiB | Viewed 3835 times ]
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 Post subject: Re: Seagate st9160821as DEAD/No power/No signs of life
PostPosted: February 25th, 2018, 21:57 
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Location: Australia
The drive is a 2.5" model, so it would have no 12V circuit. (The power specs should be on the label.)

The "KEC" part would be a 5V TVS diode. I expect that yours would be OK. If it were shorted, then your PSU would shut down.

Does the drive make a faint noise as if it is trying to spin up?

If you could upload a full photo of the PCB, I could help you locate the voltage test points.

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 Post subject: Re: Seagate st9160821as DEAD/No power/No signs of life
PostPosted: February 26th, 2018, 4:37 
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In case of a Seagate drive you should always start with COM port terminal!
The PCB looks OK.


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 Post subject: Re: Seagate st9160821as DEAD/No power/No signs of life
PostPosted: February 26th, 2018, 19:56 
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fzabkar wrote:
The drive is a 2.5" model, so it would have no 12V circuit. (The power specs should be on the label.)

The "KEC" part would be a 5V TVS diode. I expect that yours would be OK. If it were shorted, then your PSU would shut down.

Does the drive make a faint noise as if it is trying to spin up?

If you could upload a full photo of the PCB, I could help you locate the voltage test points.


I have attached a photo showing the full pcb. also I have attached an annotated photo of part of the pcb.

I have done a little testing. I have tested the components circled in red, yellow and blue; which I believe are all 0 ohm resistors. Am I correct?

The 3 yellow components have continuity, but the red one doesn't. Is the red one faulty?
The blue components tested for continuity, but only if you put one of the probes on one side of the component and the other at a point further along the circuit.

In answer to the question of if feint noise can be heard, the answer is absolutely no noise can be heard.


Attachments:
IMG_20180226_224808.jpg
IMG_20180226_224808.jpg [ 2.32 MiB | Viewed 3734 times ]
IMG_20180225_204943_annotated.jpg
IMG_20180225_204943_annotated.jpg [ 1.8 MiB | Viewed 3734 times ]
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 Post subject: Re: Seagate st9160821as DEAD/No power/No signs of life
PostPosted: February 26th, 2018, 20:52 
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Can you measure the voltages at V1 and V2? Can you tell us the markings on ICx?

BTW, Microsemi uses the same marking for two different part numbers, but the ICs are functionally identical.

LX1736, Microsemi, marking 3049, 5V, 1.25A, 1.0MHz, PWM/PFM STEP DOWN REGULATOR, 4.5V - 5.5V in, 6-pin:
https://www.microsemi.com/document-portal/doc_download/9056-lx1736-datasheet

LX13049, Microsemi, PWM Buck regulator, 1.25A, 6-pin, marking 3049:
http://www.microsemi.com/document-portal/doc_download/125237-lx13049-datasheet
https://www.microsemi.com/document-portal/doc_view/125237-lx13049-datasheet


Attachments:
LX1736_app_cct.gif
LX1736_app_cct.gif [ 12.21 KiB | Viewed 3725 times ]
LX1736_pinout_marking.gif
LX1736_pinout_marking.gif [ 5.19 KiB | Viewed 3725 times ]
TVS_3049.jpg
TVS_3049.jpg [ 327.65 KiB | Viewed 3725 times ]
ICx_V2.jpg
ICx_V2.jpg [ 232.61 KiB | Viewed 3725 times ]

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 Post subject: Re: Seagate st9160821as DEAD/No power/No signs of life
PostPosted: February 27th, 2018, 12:41 
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fzabkar wrote:
Can you measure the voltages at V1 and V2? Can you tell us the markings on ICx?

BTW, Microsemi uses the same marking for two different part numbers, but the ICs are functionally identical.

LX1736, Microsemi, marking 3049, 5V, 1.25A, 1.0MHz, PWM/PFM STEP DOWN REGULATOR, 4.5V - 5.5V in, 6-pin:
https://www.microsemi.com/document-portal/doc_download/9056-lx1736-datasheet

LX13049, Microsemi, PWM Buck regulator, 1.25A, 6-pin, marking 3049:
http://www.microsemi.com/document-portal/doc_download/125237-lx13049-datasheet
https://www.microsemi.com/document-portal/doc_view/125237-lx13049-datasheet


Hi

Thanks for the help.

I have tested the drive and here are the results:

Voltage readings:
V1 = 3.383
Large CAP to left of LX1736 chip = 4.773
V2 = 1.250
Large CAP below ICx chip = 4.777

The markings ICx are: ON LT BG

I have attached a photo of the ICx chip.


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IMG_20180227_163358.jpg
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 Post subject: Re: Seagate st9160821as DEAD/No power/No signs of life
PostPosted: February 27th, 2018, 16:23 
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Joined: September 8th, 2009, 18:21
Posts: 12587
Location: Australia
Vcore (1.2V) and Vio (3.3V) are OK.

Try to obtain a terminal log from the drive's serial port. You will need a USB-to-TTL adapter.


NTTD4401F, ON Semiconductor, FETKY P-Channel MOSFET & Schottky Diode, -20V, -3.3A, marking BG:
https://www.onsemi.com/pub/Collateral/NTTD4401F-D.PDF

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