WD6400BPVT-75HXZT3 heads stay on the ramp after heads swap

[Scorpion]

Hello everyone,

I stuck here with the following drive:
WD6400BPVT-75HXZT3 2.5 640GB.
The drive made clicking noises and didn't give any recognzation.
So I swaped the heads with very similar new and working drive.
Right after the swap, the patient drive make 2 bips noise, the heads stay on the ramp, the motor spin without stop and I got an ERR red led in PC3000 panel.
I took back the heads to the donor, the heads worked perfectly. So I took them back to the patient drive and put the 2 magnets too from the donor to the patient.
Still have the same 2 bips noise.
With a pcb from other drive with a differentt capacity the heads move towered the platters makes some clicks and return to the ramp.
So it means that there is nothing who physicaly stop the heads from moving.
I lack of ideas how to proceed with this drive.
* I used HDDsurgery ramp set tools for WD for move the heads.

This is a topic which I published before on the patient and donor drive for compitablity
wd6400bpvt-75hxzt3-heads-swap-t24429.html
I was told that those are a good match.

Donor
http://imageshack.us/photo/my-images/23/donorg.jpg/

Patient
http://imageshack.us/photo/my-images/341/img1881o.jpg/

This output from PC3000 utility:
Techno mode key
Techno mode key......................... : Ok

Debug Stop Code......................... : DEBUGSTOP CRT RAISE

RAM:
HDD Info reading........................ : Ok
Heads number............................ : 1
Cyl Count............................... : 256

Zone allocation table................... : HDDs RAM reading error - Device Error Detected: "VSCE PERM OVL NOT LOADED. LDR Upload is recomended"

ROM:
ROM reading............................. : Ok
ROM Data size........................... : 256 Kb
ROM version............................. : 65.0AE
ROM generation.......................... : 65.0AE
Link table version...................... : 05.0C.
Consolidated ROM version................ : 0065000A

ROM Modules:
Flash ROM dir reading................... : Ok
Modules directory address............... : FIXED
SA regions address...................... : by default

SA Translator loading................... : Ok
SA defects assigned..................... : 42

Heads configuration..................... : by map
Heads number............................ : 4
Heads number in use..................... : 4
Switched off heads...................... : No
Heads map............................... : 0,1,2,3
ROM Firmware version.................... : 0065000A

Service area:
SA dir reading (ID)..................... : Drive is not ready
Drive is not ready
SA dir reading (ABA/CHS)................ : Module ID 30 reading error Data request error - Drive is not ready
SA Access............................... : NONE

Configuration reading................... : Module 02 not found



Any suggestions?
Many thanks!

[northwind]

This could be a lot of things, but here's my $0.02

Did you remove that little rubber that sits on the connector? (that one that lies between the pcb and the connector).
Sometimes, after a head swap it doesn't 'sit' well and this prevents connector to touch the pcb correctly. Result? Drive spins up, usually gets ready (depends on make/model) and heads dont move from ramp.

But as I said, it could be a lot of other things.

[fzabkar]

Did you try the patient PCB on the donor drive, or the drive with the different capacity?

Did you check for VCM continuity using the test points on the PCB?

If the head stack has a different preamp, can the MCU sense this (via the I2C pins?), and does this prevent the heads from loading???

[Scorpion]

This could be a lot of things, but here's my $0.02

Did you remove that little rubber that sits on the connector? (that one that lies between the pcb and the connector).
Sometimes, after a head swap it doesn't 'sit' well and this prevents connector to touch the pcb correctly. Result? Drive spins up, usually gets ready (depends on make/model) and heads dont move from ramp.

But as I said, it could be a lot of other things.

I test it, the rubber sits fine. Moreover how it can be that other PCB cause the heads to move but make click sounds while the original PCB doesn't move the heads?

Did you try the patient PCB on the donor drive, or the drive with the different capacity?

Did you check for VCM continuity using the test points on the PCB?

If the head stack has a different preamp, can the MCU sense this (via the I2C pins?), and does this prevent the heads from loading???

Can you please put some light over what is VCM continuity and MCU?
First time that I run over those subjects while lots of succeeded heads swap operations are beyond me.

Many Thanks!

[Doomer]

I see three options.
1. PCB is dead (unlikely, considering the symptoms)
2. Preamp is not supported by the ROM revision or PCB hardware (most likely)
3. HM is not the same

Last edited by Doomer on December 19th, 2012, 10:20, edited 1 time in total.

[Doomer]

Can you please put some light over what is VCM continuity and MCU?
First time that I run over those subjects while lots of succeeded heads swap operations are beyond me.

I think you better outsource this case

[fzabkar]

Can you please put some light over what is VCM continuity and MCU?
First time that I run over those subjects while lots of succeeded heads swap operations are beyond me.

The following article is written with novices in mind, but it should explain the terms "MCU" and "VCM". It should also help you identify the preamp (it is on the head stack).

http://hddscan.com/doc/HDD_from_inside.html

As for the term "continuity", it refers to the existence of an electrical path between two points. If you have a multimeter, you would use it to test for continuity by measuring the resistance between two appropriate test points. If you don't have a multimeter, then I would suggest that it would be a prudent investment. A cheap one would cost less than US$10.

The following user manual should explain how to make a resistance measurement:

Cen-Tech 90899 7 Function Digital Multimeter User Manual:
http://manuals.harborfreight.com/manual ... /90899.pdf

Otherwise there are numerous online video tutorials.

If you are having difficulty understanding what I mean by "VCM continuity", I am simply expanding on northwind's advice by suggesting that you measure the resistance of the VCM circuit at two test points on the PCB while the drive is in its fully assembled state. This will confirm whether the PCB is making contact with the HDA connector.