The Sinclair QL Forum

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

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

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

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). 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. 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

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