Hi I am experiencing the following error minus the word "define"

define SERVO_ERROR_CODE_BASE_SvirErr 0x5420

can some body clarify on this.
It is a very interesting case and below are the details

Drive came to me as

Diabolo3s WD20EZRZ-00Z5HB0

Everything was ok but it was just a little slow. So first i backed up the essentials by every way (Mods+Tracks), Did a slow read fix
cleared RELO which was FULL.

Drive behaved ok and I started to image on DDI. The MFT area was slow but all files loaded beautifully and Imaging started.
Head number 3 was slow so I switched it off in RAM over DDI and started to image. The image time frame got reduced to merely 7hrs.

Suddently, after some time of imaging, i got a lot of slow sectors. And eventually I had to stop the process and the drive got reset.
On resetting , it began clicking and now it is 0 capacity + clicking twice before spinning down.


So to examine stuff, I put the drive in kernel mode and try to force load over DFL. It spun up perfectly with no clicking and reports "Restore Ok". Classically by a DFL manual, it would mean that heads are ok.

Now i removed the jumpers and tried to boot it up normally only to see it in err abrt after clicking twice and spinning down.

I had recalled DDI can disable heads in RAM. So i Disabled head 4,5 and kept 0,1 (this hdd has 4 heads)
still the capacity was 0. and DDI could not make the drive read SA and share capacity from 0/1 like other cases which are solved using this technique.


So i took the HDD to DFL back and i did a bypass SA read. Now, generally if one bypasses SA read and the drive stops to click,
it would mean it is a firmware problem. However in this case, the drive clicked and stopped as before.
Now I disabled head number 5 and restarted the drive only to see the drive spinning normally and SA loading up after auto get detail.
Also all the loaders load perfectly when 5 is turned off in ROM.


Luckily i had a near close donor with same ROM microcode and tried to hot swap in DDI.
Luckily it detects.
The behavior noticed is:-
when the donor is attached and detected normally in ddi, one disables head 5 and then spins it down. After the swap, when the patient is spun up either by going to disk passport or trying to select drives, the patient spins so perfectly, detects. But when I try to image, it enter bsy state and does not respond only making it NOT RESPOND.

If the head 5 is turned on and the swap is done, the patient clicks clicks clicks and fails to spin down. After a while it detects and then again when data is sought for, it enter bsy states and returns a not responding msg.

So turning the 5 on yields clicking even with SWAP and even after by pass SA read.

SERVO_ERROR_CODE_BASE_SvirErr is the error of the day.
Please tell me what is this case all about now ? Is a head replacement deemed necessary ?

thanks folks
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SERVO_ERROR_CODE_BASE_SvirErr .... I think that either ALL heads are gone or pre-amp is gone. On my experience and it's not big when i do get that message there are ALWAYS the need for clean room work + head stack replacement.

Those SERVO ERROR messages are displayed when heads can't even find servo marks. If you do have other sort of firmware problem you don't get that servo message as the drive needs for the heads to find servo and position correctly on the platter to read firmware at all. If the don't even find servo marks they will not read ANY firmware as they can't locate sectors containing the code on the platter....

For me it's time to do a head stack replacement.

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There is a list of error codes given over Russian forums
How does one interpret them?

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