Microdrive Motor Adjustment

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tcat
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Location: Prague, Czech Republic

Re: Microdrive Motor Adjustment

Postby tcat » Wed May 10, 2017 5:57 pm

Hi,

I removed a faulty R/W head from one of the units here. I wish to inspect it inside, to understand what went wrong with the erase coil, could it have been burnt by excessive current, or just its pins not soldered properly in the production or disconnected during factory assembly.

The head inside is filled with some poly-plastic, any ideas how I could go about removing it from the corpus?

Many thanks.
Tomas


Dave
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Re: Microdrive Motor Adjustment

Postby Dave » Wed May 10, 2017 6:17 pm

They're potted with epoxy. Use a commercial epoxy dissolver like Loctite 76820. Google what's available in your area.


tcat
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Re: Microdrive Motor Adjustment

Postby tcat » Fri Aug 04, 2017 9:53 am

Hi,

In the end I drilled two holes, aiming around erase coil points, probes of my voltmeter measure ~96ohm, so I believe the head came as faulty from prime production during assembly.

This may shed a bad light on quality management, or could they have been sourced for discount as faulty on purpose?

Tom


tcat
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Location: Prague, Czech Republic

Re: Microdrive Motor Adjustment

Postby tcat » Fri Aug 04, 2017 2:18 pm

Hi,

This is one of the four drives I have here for tests and maintenance.
I have managed to replace its R/W head for the good one (thanks to Charles, he has donated a spare).
md-head-replace1.JPG
faulty head desoldered + dismounted

To the right you may see a motor position jig, plus some watchmaker's tiny screws.


The result after fitting good R/W head. Drive had its motor repositioned, head reseated on all four legs, clutching side spring retensified, head springs aligned, new roller fitted. EDIT Ah, forgot, motor speed verified to be OK.
md-head-replace2.JPG
good head fitted

The drive now formats, and pass R/W tests, appears anew in generally good healthy condition.

I have two more MD units to service, but only one good R/W head left. Anyone willing to supply one, I can swap for ULA I salvaged from another unit?

Many thanks.
Cheers from Prague.
Tom


tcat
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Posts: 429
Joined: Fri Jan 18, 2013 5:27 pm
Location: Prague, Czech Republic

Re: Microdrive Motor Adjustment

Postby tcat » Tue Nov 07, 2017 3:00 pm

Hi,

Just serviced another drive, that makes 3 of 4 total.
Last drive is R/ only because of faulty erase coil, and none spare head left.

Tom



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