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Where is the rom chip?
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pupuplader
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Joined: 17 Apr 2010
Posts: 9

PostPosted: Mon Apr 19, 2010 1:56 pm    Post subject: Where is the rom chip? Reply with quote

So in the last month all three of my hard drives have failed. So I started looking around to see how to fix them. I know that you need to find a matching PCB # and that it helps if they are manufactured close the the same time and finally if you switch the firmware chips that everything should work out fine.

My problem is that I have a WD6400AAKS-007B0 and there is no rom chip:
[img]http://i560.photobucket.com/albums/ss47/obscurefragments/P4170576.jpg?t=1271684818[/img]
What do I do when there is no rom chip?

One is an external drive Seagate Barracuda 250GB which has a burnt piece on it:
[img]http://i560.photobucket.com/albums/ss47/obscurefragments/P4170574.jpg?t=1271685043[/img]
If I replace the burnt piece will it work again, also what is that piece? This drive doesn't have any of the parts labeled so if I need to replace the PCB altogether where is the rom chip on that guy.
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pupuplader
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PostPosted: Mon Apr 19, 2010 2:01 pm    Post subject: Reply with quote

Sorry cant seem to get the images to work properly.
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harddrivespecialist
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PostPosted: Mon Apr 19, 2010 6:13 pm    Post subject: Reply with quote

On WD drive, you have to reprogram ROM info to a new board, because its stored in Processor chip.
Seagate has TVS chip burned. If you replace it, drive should work.
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pupuplader
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PostPosted: Mon Apr 19, 2010 7:03 pm    Post subject: Reply with quote

Where would you suggest buying the TVS chip (Digi-Key), and where would I look to find the actually part number?

Do you have a link on how to reprogram the rom?

Thanks for the help
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fzabkar
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Joined: 02 Apr 2010
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PostPosted: Mon Apr 19, 2010 11:44 pm    Post subject: Re: Where is the rom chip? Reply with quote

The 5V and 12V TVS diodes can be replaced by an SMBJ12A and SMAJ5.0A, respectively. These are available from Digikey, Mouser, Farnell.

BTW, you can remove the shorted TVS diode. The drive will work without it, but there will no longer be any protection on the affected supply rail. Be certain your PSU is OK.
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fzabkar
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PostPosted: Mon Apr 19, 2010 11:53 pm    Post subject: Re: Where is the rom chip? Reply with quote

If both your drives failed in the same box, then it could be that your WD board also has a shorted TVS diode.

Check D3 and D4 near the power connector for shorts, and R67 and R64 for open circuits. The zero ohm resistors behave like fuses.

Measure the resistance of each device with a multimeter set to the 200 ohms range.
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pupuplader
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PostPosted: Tue Apr 20, 2010 12:17 am    Post subject: Reply with quote

The seagate is from an external hard drive that failed about four weeks ago.

The other two where internal hard drives, the WD6400AAKS-007B0 was my main drive and had all of my info on it. The other hard drive was actually blank at the time so I am not concerned about it.

So I bought another two radeon 4850 and was going to crossfire them. Both the motherboard (DFI Lanparty X38-T2RB) and power supply (SeaSonic SS-650HT) are Crossfire certified.

I installed the new graphics cards. Made sure everything was hooked up and then plugged the computer back in. Pressed the power button and lights flash on the front and mobo for a second then nothing. Pressing the power button again nothing happened.

After testing one component at a time in another computer I found that the power supply, motherboard, and both hard drives no longer worked.
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pupuplader
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PostPosted: Tue Apr 20, 2010 12:32 am    Post subject: Reply with quote

D4 gives infinity
D3 gives infinity
R64 is zero
R67 is zero

On the 2K ohm range D3 give 441 ohms
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pupuplader
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PostPosted: Tue Apr 20, 2010 12:58 am    Post subject: Reply with quote

I just talked to my brother (I was at his house when the external failed) and he told me that he through out the power cable to the external drive. If I take out the drive can I just hook it up like a normal internal drive?
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sunnydreamspace
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PostPosted: Tue Apr 20, 2010 3:24 am    Post subject: Reply with quote

pupuplader wrote:
I just talked to my brother (I was at his house when the external failed) and he told me that he through out the power cable to the external drive. If I take out the drive can I just hook it up like a normal internal drive?

yeah. you can if the drive is fine.

for WD6400AAKS PCB, you had to find out the same model PCB and program right firmware into PCB. ****just simple replacement PCB won't help any more even you find out one drive matching all spec with your**** and this PCB model is 2060-701590 or 701537 am i right?

for seagate i guess you can try to repair it if you can. and take off PCB when you power it up. don't make it worse.

i can handle these case. i have this PCB in stock and be able to help you program right firmware into PCB. please contact me by email or MSN.
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fzabkar
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Joined: 02 Apr 2010
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PostPosted: Tue Apr 20, 2010 4:11 am    Post subject: Re: Where is the rom chip? Reply with quote

[quote="pupuplader"]D4 gives infinity
D3 gives infinity
R64 is zero
R67 is zero

On the 2K ohm range D3 give 441 ohms[/quote]

All those measurements are OK.

Try cleaning the preamp contacts at J1 with a soft white pencil eraser.

If you are game, then you could investigate the fault a little further.

With the board disconnected from the drive, and powered up on its own, carefully measure the voltages at the three switchmode regulators. These are near the SMOOTH motor controller. The test points would be L1, L2, L3, D2, and D1. Use the screwhole as your ground reference.
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pupuplader
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PostPosted: Wed Apr 21, 2010 10:26 pm    Post subject: Reply with quote

I am always game for hardware troubleshooting Very Happy

L1 1.2mV
L2 5.2mV
L3 zero
D1 5.1mV
D2 zero
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fzabkar
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PostPosted: Fri Apr 23, 2010 7:07 am    Post subject: Re: Where is the rom chip? Reply with quote

Assuming you made the measurements on the DC voltage scale, then it would appear that there is no life in any of the onboard regulators.

My understanding is that the motor controller chip also controls these regulators. This would suggest that this chip is either brain dead, or is not receiving a particular signal, or supply rail, that it needs.

Unfortunately I don't have a datasheet, so any further troubleshooting is beyond me. At this point I would need to do some circuit tracing, and/or break out my oscilloscope. :-(
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pupuplader
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PostPosted: Sat Apr 24, 2010 1:54 am    Post subject: Reply with quote

I do have an oscilloscope at work that I can use. If you could suggest where I should start looking or what I should look for I am up for it. I appreciate the help so far fzabkar.
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fzabkar
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Joined: 02 Apr 2010
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PostPosted: Sat Apr 24, 2010 4:43 am    Post subject: Re: Where is the rom chip? Reply with quote

When troubleshooting microprocessor based logic, I check these things:

1/ power supplies
2/ oscillator
3/ reset pin
4/ activity on data and address buses

The coils and diodes that you've measured are part of several onboard switchmode regulators. These appear to be under the control of the L7251 SMOOTH motor controller (U1).

Here is a datasheet for an L7250, SMOOTH, spindle motor + VCM controller, ST Microelectronics:
http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXyuswx.pdf

I don't know how similar the two chips are, but at least you should be able to understand their basic function from the application circuits in the datasheet.

Another test point for one of the supplies would be the Vcc pin at the unpopulated ROM location at U12 (probably pin 8). There should also be a couple of supply pins at the preamp connector (J1). One may be a negative voltage.

I would also check the crystal at Y1. Be aware that your scope's input capacitance may load the crystal, especially on the x1 range, in which case an absence of oscillation may be inconclusive. Use a x10 probe, if possible.

The location of the reset pin is a mystery, but I expect that there is a POR pin on the SMOOTH chip that provides the power supply supervisor function.

The address and data buses are internal to the MCU, so this avenue appears to be closed. However, between the Marvell MCU and the SMOOTH chip, there must be at least two serial clock and data lines which should be showing some activity.

One other thing to do is to test each active device, ie diodes (D) and transistors (Q), with a multimeter. Also confirm that no coil (L) is open circuit.

I believe that WD drives also provide RS232 serial terminal access (via connector J8 ???), but I'd need to do some research to be sure. No doubt one of the data recovery guys could tell you.

You should also test the motor windings (3 phases plus common ?) for shorts and opens.

To help you in your search for datasheets, here are my scratchpad style notes:
http://www.users.on.net/~fzabkar/HDD/HDD_ICs.txt
http://www.users.on.net/~fzabkar/HDD/TVS_diodes.txt
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