Seagate ST-4026 Hard Drive Sounds - Voice coil, but linear!

Описание: Here’s an interesting drive, a voice coil unit, but unlike most voice coil drives, this one is linear!

The ST-4026 is an early 5.25 voice coil drive from the mid 80s, with a massive linear mechanism!
Even with the large mass moving around, those drives benefited from much faster seek times compared to the common stepper drives from the same era. The downside of the voice coil mechanism is that it needs a whole surface for servo information, meaning a drive like this which has 4 data heads actually needs a 3rd platter for the servo. Most drive that required a servo surface went with a odd number of data heads instead. Seagate probably did it this way on the ST-4026 to keep the drive compatible with the standard 20MB type 2 (615/4/17), even if it means a entire surface is wasted.
Another downside now that the drives are old is that, if the servo surface gets damaged, or the drive cannot read the servo data for any reason, then it’s dead…

Luckily, this drive I got here is in perfect shape and works great, with a single visible bad sector listed on the factory defect list (actually the factory list has 2 bad sectors on it, but the second one didn’t even show up!). I only needed to replace a shorted electrolytic capacitor from the top PCB to make it work. Speaking of the PCB, the electronics of this drive are very complex with two PCBs and a lot of ICs. On their later linear voice coil drives Seagate did away with the top PCB and simplified the electronics significantly. Those newer drives go as high as 80MB (with the MFM ST-4096, the ST-4144R being the same drive but RLL certified, reaching 120MB) and have a significantly different seek test.

As far as I know, Seagate only made Full Height linear voice coil units, but other brands actually made Half Height drives, which also have faster seek times. Unfortunately, this ST-4026 is the only linear voice coil drive I have so far.

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