Repairing Amstrad CPC disk drives

I decided to resurrect my old Amstrad CPC 464 and CPC 6128 computers.  As I suspected, the disk drives were no longer working.  After much internet research and buying supplies, I set to work.

Everything ready for the repair: the 6128, repair guide on the iPad, new drive belt, alcohol and cotton buds for cleaning, Vaseline for lubricating the worm gear:

Cover off:

The main circuit board:

Disk drive removed:

This was a problem before on this machine, although not mentioned in the repair guide. There’s a spring loaded arm that presses the disk surface onto the read head. It’s supposed to have a felt pad, but it’s gone. At best, that means no pressure on the read head, causing mis-reads. At worst it means the plastic arm gouges grooves in the disk surface, permanently ruining it!

So I cut out some fabric (from an old glasses cleaning cloth) and glued in on the arm:

Photographing the cables before I remove them for reference when re-attaching!

Ah, so this is what happened to the drive belt (bottom right). For reference, it shouldn’t look like that!

Compare the old and new drive belts!

Cleaning up the brass drive capstan (top right):

Wow, all the perished rubber made a mess! The repair guide was right about needing the alcohol and how important it was to get the old residue off!

The new belt installed:

But it still doesn’t work. Progress though. Before I got a horrible noise, and ‘no disk’ errors. Now I get a silky smooth whirring sound, and ‘bad command’. But no head seek noise, which is suspicious:

I remembered I’d forgotten to grease the head worm gear with Vaseline. So now I reopen the case and do that. Still no head movement. I manually turn the shaft a few times, and it frees it up. Now it moves under power. I no longer get ‘bad command’, instead I get read errors:

I wonder if the disk is being pressed sufficiently on the head head, or is being pressed too hard. So I pull up the pressure bar – no difference. Then I gently press it down with my finger as the drive runs – success!

So the material I put on the pressure bar wasn’t thick enough. I cut out some more circles and glue one on. Now it seems to work reliably:

And the drive working when reassembled:

Yay, it works

Now to fix the external drive for the CPC 464:

Opening it up:

Jess is “helping”. I’ve not really sat down for longer than 20 minutes at a time in the last month because of a bad back injury, so she’s taking the opportunity while she can:

The insides. A different model of disk drive inside (it’s about two years earlier than the 6128 drive):

That’s one hell of a power supply just for a floppy drive!

The original felt pad (that gave me lots of grief on the 6128 drive) is still intact on this one

The worm gear is in a different place and of a different design compared to the other drive:

The circuit board:

One fewer connector too:

But this connector is a bugger to get to because the cable is so short, and the big black (non removable) wire prevents lifting the other side much:

In the end I had to bend the metal retaining piece to release the big black cable to give me more room:

And I’m in, although the circuit board is very tight, and doesn’t give me much room to get to the brass capstan:

Cleaning up the residue on the capstan from the disintegrated drive belt:

This one didn’t leave nearly as much mess as the 6128 drive did:

The new drive belt installed:

The short ribbon cable makes reassembly harder than the 6128 drive. But got it all together again, and now it works perfectly