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Data recovery and disk repair questions and discussions related to old-fashioned SATA, SAS, SCSI, IDE, MFM hard drives - any type of storage device that has moving parts
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Fujitsu MHV2100AH: head fails

January 10th, 2018, 14:38

Hi, this is my first post here. I love to repair all sorts of things (sometimes it fails), from cars to watches.
It is for me always a big satisfaction to bring something broken to work again.
After reading in this forum, I learned that repairing a hdd is a BIG challenge, which only gives me more incentive to try it.

I have a 2.5" 100Gb IDE hdd, model Fujitsu MHV2100AH , which has been wrongly powered with 12V instead of 5V, and was'nt responsive anymore.
Data on the drive is not too important, even if I'd like to recover it.

Hoping just the electronic PCB was gone, I found an identical drive, same country of origin , with most numbers matching.
With swapped PCBs, the motor is now speeding up but absolutely no noise comes from the heads: no clicking, nothing!.
Donor PCB is ok: put back on the donor drive it is still working.

Here are fotos of the broken drive and its pcb
Image
Image

And of donor drive and pcb.
Image
Image

As electronics tech and engineer, I think in any case the servo arm with heads should be replaced, but want also a wise advice from specialists, the big question beeing: would this be sufficient ? I've been searching in this very interesting forum for hours, but without finding an explicit answer.

Thank you for your help.

PS: I have access to a clean room, where I've already repaired the cam (lens mecanism) which took the hdd fotos.

Re: Fujitsu MHV2100AH: head fails

January 10th, 2018, 15:53

To start a direct PCB replacement will not work. This is because there are "adaptives" on ROM that should match the drive. Did you swap ROM chip from the broken PCB to the good one ? If not I would start by that.

Find the ROM chip (if any) on the "broken" PCB and move it to the donor PCB. Then attempt to plug the drive. Any clicking sound ?

Maybe the pre-amp is damaged (inside the drive) because of the over-current. If the heads still don't move even with the correct ROM chip in place then i would say there is a good chance that the pre-amp is gone ....

Re: Fujitsu MHV2100AH: head fails

January 10th, 2018, 16:17

No specific “adaptive” info in these. The PCB’s appear compatible to me and should have worked if preamp survived.

Preamp failed IMHO, so requires head swap.

To be sure, it may be an idea to fix the original PCB.

There is a fuse on these boards, so please show the component side of the bad PCB.

Re: Fujitsu MHV2100AH: head fails

January 10th, 2018, 16:19

Could we see the other side of the PCB, ie the side with the electronic components on it?

Re: Fujitsu MHV2100AH: head fails

January 10th, 2018, 16:40

pcimage wrote:No specific “adaptive” info in these. The PCB’s appear compatible to me and should have worked if preamp survived.

Preamp failed IMHO, so requires head swap.

To be sure, it may be an idea to fix the original PCB.

There is a fuse on these boards, so please show the component side of the bad PCB.


I was under the impression that even old 3.5 MPG Fujitsu drives would have unique info on ROM (Adaptives).... I don't know about this particular 2.5 IDE model so i might be completly wrong....

Re: Fujitsu MHV2100AH: head fails

January 11th, 2018, 4:42

Many thanks for your answers :)

About the fuse: I found the info in this forum (did'nt imagine there is a fuse there): SMD marked with N and connected to TP1.
Measured it on the broken drive: blown .
So I just applied 5V power with an USB-IDE adapter, and shorted the fuse. Motor did'nt spin up, but MCU (chip 88i6632-BAN1) became hot, so it is probably dead, although there is no visual damage.

PS: Will post foto of the components side (don't have the drive here at the moment)

Re: Fujitsu MHV2100AH: head fails

January 11th, 2018, 14:09

Hi, here you have a foto of PCB components side, if it can be of some help.

Image

Both PCBs are identical in components.
Fuse is component with N mark in red circle, and the yellow square seems to show there is no ROM here.

As my understanding, only thing I can try now is to swap heads ?

Re: Fujitsu MHV2100AH: head fails

January 11th, 2018, 18:54

I would try to confirm whether the preamp may have been damaged. To this end I would start by measuring the Vcore and Vio voltages on both PCBs.

I would then determine if there is any continuity between the pins of the HDA connector and Vio and +5Vin. This will tell us the power supply requirements of the preamp on the headstack (either +5V or +3.3V, or both). If the preamp gets a positive supply directly from the external +5V input (via the fuse), then it has probably been damaged.

I would compare the resistance between the relevant supply and ground of each of the donor and patient HDAs (by mounting the donor's PCB on each HDD). This will enable us to compare the resistances of the donor and patient preamps.

BD9109FVM, Rohm, 4.5V - 5.5V, 0.8A, 1ch Buck converter:
http://rohmfs.rohm.com/en/products/data ... 6fvm-e.pdf
Attachments
Vcore_Vio.jpg
HDA_conn.jpg
HDA_conn.jpg (90.42 KiB) Viewed 2630 times

Re: Fujitsu MHV2100AH: head fails

January 12th, 2018, 5:05

Thank you so much,fzabkar.
This is a very valuable information :good: . I will check all this this week-end.

There is one thing I do'nt understand:
Various posts here say that without (working) preamp, the disk woul'nt spin up. In my case, it IS spinning up with the good PCB: so in this case the preamp should be OK.
BUT as the heads do'nt make any noise at all, something would be failing in the servo actuator.
Thinking earlier that the servo winding is driven directly from the pcb, I tried unsuccessfully to find its resistance directly on the drive side HDA pins. I am not sure I tried it also on the good drive, fearing the multimeter could induce a failure inside.
But the winding could also be fed by the preamp... :?:

Re: Fujitsu MHV2100AH: head fails

January 12th, 2018, 5:56

i would try with same FW version of pcb, or replace the mcu on good pcb

Re: Fujitsu MHV2100AH: head fails

January 12th, 2018, 7:45

helpdisc wrote:i would ... replace the mcu on good pcb

repfanatic wrote:MCU (chip 88i6632-BAN1) became hot, so it is probably dead, although there is no visual damage.

Re: Fujitsu MHV2100AH: head fails

January 12th, 2018, 7:57

yes you are right.
Did not read it good.

Re: Fujitsu MHV2100AH: head fails

January 12th, 2018, 8:16

I would measure the resistance between ground and each of Vcore and Vio, and then compare the readings against the donor's. An excessively low reading for Vcore would confirm that the MCU is dead.

Re: Fujitsu MHV2100AH: head fails

January 12th, 2018, 8:37

repfanatic wrote:Various posts here say that without (working) preamp, the disk woul'nt spin up. In my case, it IS spinning up with the good PCB: so in this case the preamp should be OK.

A typical failure mode of some preamps is a short between supply and ground. This will prevent the PCB from powering up.

Some drives need to detect a preamp before they will spin up, others don't. I'm not a data recovery professional, so I don't know how your model should behave. However, you could try to isolate the HDA contacts on you donor drive with a business card, assuming that the motor contacts are still able to make solid contact.

repfanatic wrote:BUT as the heads do'nt make any noise at all, something would be failing in the servo actuator.

If you wish to rule out this possibility, measure the resistance between the VCM pins with the PCB on and off the HDA.
Attachments
VCM_HDA.jpg

Re: Fujitsu MHV2100AH: head fails

January 12th, 2018, 15:36

Agree. If the drive needs to detect pre-amp then it might spin and not move heads if it can't detect pre-amp !

In other words, a shorted pre-amp (damaged) would prevent the drive from spinning but a damaged pre-amp that is not shorted wouldn't prevent the drive from spinning but if the code checks the pre-amp version and the pre-amp is damaged (but not shorted) then the drive might spin and still it won't work.

To see if this is true for your model pick the good one and insulate the head contacts. If the drive spins and doesn't move heads then it's necessary for pre-amp to ID itself.

Re: Fujitsu MHV2100AH: head fails

January 12th, 2018, 17:50

Spildit wrote:To see if this is true for your model pick the good one and insulate the head contacts. If the drive spins and doesn't move heads then it's necessary for pre-amp to ID itself.

If you isolate the entire HDA connector, then you would be isolating the VCM contacts as well.

Re: Fujitsu MHV2100AH: head fails

January 13th, 2018, 15:35

Here are hi-res photos of the PCB:

Fujitsu CA26332-B43104BA hires PCB scans:
http://www.hddoracle.com/viewtopic.php?t=2237

Re: Fujitsu MHV2100AH: head fails

January 13th, 2018, 17:10

fzabkar wrote:Here are hi-res photos of the PCB:

Fujitsu CA26332-B43104BA hires PCB scans:
http://www.hddoracle.com/viewtopic.php?t=2237


Yes, i did find it there some hours ago and did reply to the thread !

Also wouldn't those be the VCM contacts ?

1.jpg
1.jpg (28.75 KiB) Viewed 2424 times


As long as you don't insulate those the drive should spin if it doesn't check for pre-amp info, right ?

Re: Fujitsu MHV2100AH: head fails

January 13th, 2018, 17:22

VCM = Voice Coil Motor, not spindle motor.

Re: Fujitsu MHV2100AH: head fails

January 13th, 2018, 18:12

fzabkar wrote:VCM = Voice Coil Motor, not spindle motor.


Ups .... Yes, you are correct.

Forget it.

:oops: :oops: :oops:
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