Help Identifying a component. - Page 1
Forum section: electronics / beginners

author: Menohac
author_rank: Newbie
timestamp: December 06, 2013, 10:41:26 pm
content: Hey guys, I have a hard drive that has stopped working, and I am trying to fix it. It seems to still be seen by the computer but it cannot be accessed, it doesn't make any sound, and I cannot "feel" it running either, so I am assuming it is the motor, motor controller that has failed or something going to it.While probing around on the PCB of the drive I found what I _THINK_ is a SMD fuse, and I want to confirm this before I try to rip it off and find a replacement. I will attach a picture below also, but using my trusty old fluke, the continuity test does nothing, and it is reading over 1Mohm, and it kinda looks like an SMD fuse.I must apologise, I am rather rubbish at SMD, I am still a through hole hobbyist, and I never learned much about SMD in my EE classes.The component in question is the large white one with bG on it, marked as SK1.

author: Skimask
author_rank: Super Contributor
timestamp: December 06, 2013, 10:46:20 pm
content: Swap the leads. Might be a diode.

author: Fagear
author_rank: Regular Contributor
timestamp: December 06, 2013, 10:50:48 pm
content: I think it is accelerometer (shock sensor). No need to touch it.Check SMOOTH temperature after applying power. It is motor driver. If it gets hot - it is dead. If it not - it must try to rotate spindle and produce some sounds. If not - may be controller chip dead (also check temperature) or ROM corruption.Also check for overvoltage protection diods near power connector - they may become short circuit if voltage was too high.

author: Menohac
author_rank: Newbie
timestamp: December 06, 2013, 11:06:41 pm
content: No continuity no matter what way the leads are.Can accelerometers have only 2 connections? All the diodes near the power connector are working fine. As for heat, I will have to check tomorrow.

author: Fagear
author_rank: Regular Contributor
timestamp: December 06, 2013, 11:13:56 pm
content: I think it is not IC-type accelerometer. It is some sort of piezo-sensor.There are current shunt resistors for motor driver - check R8 right to SMOOTH on your photos.Those SMOOTH are likely to become dead. But usually it looks like this (also you can see SK1 footprint and part is not populated - these accelerometers are not always installed):

author: xygor
author_rank: Regular Contributor
timestamp: December 06, 2013, 11:17:16 pm
content: Quote from: Menohac on December 06, 2013, 11:06:41 pmYes they can:http://www.electronicproducts.com/Electromechanical_Components/Shock_sensor_prevents_hard-disk_drive_data_corruption.aspxEdit: oops, the above link doesn't prove that. A 2-terminal piezo sensor can use an external amplifier. I don't have an example at the moment.

author: robrenz
author_rank: Super Contributor
timestamp: December 06, 2013, 11:22:55 pm
content: The SK3 pads have inner traces that are typically the sense leads of a 4 wire connection using a standard smd resistor. That may imply that SK1 is also a current sense resistor.

author: xygor
author_rank: Regular Contributor
timestamp: December 06, 2013, 11:29:29 pm
content: Ok here's an example.http://media.digikey.com/PDF/Data%20Sheets/AVX%20PDFs/PMLE480W-R.pdf

author: Menohac
author_rank: Newbie
timestamp: December 06, 2013, 11:47:57 pm
content: I'll so some touch tests for heat tomorrow.I get the feeling it might be easier to just find a replacement board on eBay....

author: Fagear
author_rank: Regular Contributor
timestamp: December 06, 2013, 11:58:06 pm
content: Quote from: Menohac on December 06, 2013, 11:47:57 pmNot exactly. It may work for very old HDDs.But today there are some unique parameters in ROM chip on your board. If you'll just replace the board without replacing ROM (soldering ROM from original board to new one) - you can ruin your HDD and you will have no way back.Also there are many problems with different boards. They must be as equal as possible to replace. Sometimes if one digit on the board markings is different - it will not work. Sometimes you have to find board with exact same controller chip (for those boards that can have some variants for main chip) with all markings same. There are many difficulties on this way that can lead you to totally unrecoverable HDD.

author: SeanB
author_rank: Super Contributor
timestamp: December 07, 2013, 02:03:02 pm
content: Place in a sealed bag and leave in freezer overnight then try it again and see if it spins up. Otherwise shake gently around the motor axix to free a stuck motor. Does it do anything when power is applied, like click or any slight noise? If not then motor or driver is dead. If data is important then try, otherwise Drivesavers and $$$ before anything else that will damage the data.