Amiga A1010 3.5″ FDD Repair & Restoration

I recently acquired my first Commodore Amiga A1010 3.5″ FDD, another vintage disk drive to add to my collection. The drive was in reasonable condition and came with several accessories and its original box, however it was bought sold-as-seen.

The Commodore Amiga 1010 3.5″ FDD was released in 1985 alongside the Amiga 1000, or A1000, and features a similar a similar case design. It supports 3.5″ double-density (DD) 880 KB floppy disks, and connects to the Amiga range of home computers through the external drive port, via a DB-23 connector cable.

The A1010 sold in reasonable numbers between 1985 and its discontinuation, and as such they are relatively easy to find to find – there are usually a couple up on eBay at any one time, but they often command relatively high sale prices.

The drive was “sold-as-seen” in unknown, untested condition – physically it seemed in reasonable condition, with some noticeable scratches on the case.

I hooked it up to my Amiga 1200 and tried loading a system disk, and the drive seemed to work OK. The drive also passed read performance tests OK using an Amiga Test Kit disk, however it didn’t seem to be able to write disks at all.

I cleaned the read/write heads using a 3.5″ head cleaning disk, however this made to difference. I therefore decided to remove the original mechanism (a Mitsumi D357), and check it over to see if there was anything obviously wrong.

I also took this opportunity to check the interface board and DB23 cable (in case there were any problems with these, particularly breaks in the write control lines) by temporarily fitting a known-good A1010 mechanism – this worked fine, so the issue was definitely with the original mechanism specifically.

With the mechanism removed, I dismantled it to check for any obvious electrical or mechanical problems (i.e. leaking electrolytic capacitors, head damage, flex cable damage, PCB damage or corrosion, etc), however everything looked OK. I also reseated all of the connectors and flex cables in case there was an intermittent contact on one of them, however there was no change in symptoms.

At this point, I concluded that repairing the original mechanism was beyond my abilities, and started searching for a suitable replacement mechanism in working condition.

Luckily, a kind member of the Commodore & Amiga Group UK on Facebook was happy to sell me a spare drive from their A500 (a Chinon FB-354) for a reasonable price, which had been working fine before being replaced with a Gotek drive.

The Chinon FB-354 was one of the mechanisms originally used in the A1010, so should fit fine – however, because this was used as an internal drive, it required minor modifications before it would be fully compatible for use as an external drive.

These modifications were entirely down to the activity LED, which is not fitted on internal drives: firstly, I removed the connector and flying lead from the original mechanism, and soldered this to the pads marked “A/K”; secondly, I installed a 2k2Ω resistor (just a 0.25W radial type, as I didn’t have any SMD parts) onto the pads marked “R13”, the LED current-limiting resistor which wasn’t fitted from the factory.

This process is shown in detail in a very useful video from renowned YouTuber Jan Beta.

With the new mechanism installed, all read-and-write performance tests now passed correctly, and the activity LED still worked OK.

After all this work was performed, I did some finishing up: I cleaned the read/write head and stepper rails on the mechanism using cotton buds and 99.9% IPA, and lubricated the stepper rails and disk mount using lithium grease; I thoroughly cleaned the case inside and out using Cillit Bang general-purpose degreaser, a microfibre cloth for large areas, and a toothbrush for small areas, as well as some baking soda on some of the larger scratches.

The drive seemed to work OK, but thorough testing is necessary to verify correct operation, so I did as much testing as I could.

Another restoration complete, and another Commodore disk drive saved!

Published by themightymadman

A conscientious, intelligent and committed graduate engineer, with excellent interpersonal skills, an eye for detail and a keen interest in hardware design, mathematics, and software development.

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