> On Jan 17, 2023, at 5:09 PM, Chuck Guzis via cctalk <cctalk@classiccmp.org>
> wrote:
>
> On 1/17/23 13:58, Paul Koning via cctalk wrote:
>>
>> No, 844 drives use linear voice coils (linear motors), which seems to have
>> become the norm in the early 1970s. RK05 is another example. The term
>> "voice coil" is used because they look like oversized versions of the coil
>> that drives the speaker cone in loudspeakers. These all are some sort of
>> servo device; in many of them the servo signal is on the media, but not
>> always. For example, the RK05 uses a pattern of lines on a glass substrate
>> attached to the actuator; the "fault" light on the drive indicates a failure
>> of the light bulb that illuminates the servo pattern.
>>
>> A common feature of linear motor actuators is an emergency retract circuit,
>> powered by rather large capacitors, to pull the heads off the disk if there
>> is a power failure.
>>
> And, IIRC, a bit red warning sticker on the actuator.
>
> --Chuck
Yes indeed. Triggering the emergency retract with the drive open for service
could easily take off fingers. The amount of power involved in moving those
head stacks around is pretty substantial.
paul
