st4000dm - heads melted into ramp !

[Alandata Recovery]

Have you ever seen this ?

The tangs on the head lifters have melted down into the plastic ramp.

How does this happen ?

The drive powers up and tries to move the heads.

Then spins down.

Inside looks normal, nothing burnt....

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[德亦資料救援]

Hi ,
is it a laser head?

Alandata Recovery <in...@alandata.com> 於 2026年9月25日週五 下午1:18寫道：

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[RecuperoDati299]

Yes

seen already

shortcircuit

in the two occasions we have seen this: bad luck , it ruined the platter's surface too

Robert @ RecuperoDati299 

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[pbzcbf...@gmail.com]

Show us the PCB.

[Alandata Recovery]

How did it ruin the platters?

I was worried about that. 

Breathing on the platter showed a weird pattern. Half of normal mottled pattern, other half is clear like a possible layer of fumes were deposited. There are no circular patterns. 

Did you try to clean the platters first?

So the theory is that a fault caused the piezioes or the head to stay charged long enough to get hot.

Possible heat sources if left on; 

Write coil

Read coil

Height adjust 

Piezeo 

These should have Intermittent short pulses - not remain powered, 

so this could be firmware problem.

The flight height adjustment in the head uses heat to expand the write element.

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On Fri, Sep 25, 2026, 1:48 AM pbzcbf...@gmail.com <pbzcbf...@gmail.com> wrote:

Show us the PCB.

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[compos mentis]

I'm wondering whether the PCB is native.

Is it still possible to execute a head resistance test?

The AFH heaters would be contained within the head pads. If there was a
malfunction in that area, I would expect to see severe damage in the
pads. Likewise for the write coils.

The piezo-actuators should have a very high resistance. That would be
easy to test. I can envisage an unlikely failure where one element
becomes shorted, but not all of them. :-?

"Read coil" -- there is no read coil. These last appeared in MFM drives
35 years ago.

"The flight height adjustment in the head uses heat to expand the write

element." -- There is a separate heater for AFH. It expands the head pad.

[wayne horner]

We put that board on a donor drive and it sounds great almost came ready. 

This must be a firmware bug.

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[RecuperoDati299]

The platters in our cases were ruined because ramps were melted on the platter too

Though if you have proper pads you can try to clean the platters with non aggressive super volatile agent, like Avio gasoline, i.e. trichloroethylene, either if this, realistically, won't remove eventual vaporized plastic (from extreme-heat melting) that has condensed and deposited on the surface (that coul be the case of the pattern you've observed)

Avoid ketones , since  with any ketones, the experience has been that of an (invisible) alteration of the platter coating, which subsequently was killing the heads. An exception could be butanone but we didn't made a second experiment with a brand new drive. Mean: beware try it first on a perfectly healthy, sacrificial drive.

Robert @ RecuperoDati299

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