Re: ProFile maintenance hints?

[Patrick Schäfer <Patrick.Schaefer@topmail.de>]

Dakin Williams schrieb:

> The drive is working OK, but seems noisier than I remember and takes longer
> to spin up to speed (when the ready light comes on).
> 

ST506 mechanisms ARE noisy. You can disassemble the profile, remove any
dust located under the analog pcb and put a drop of oil on the tip of
the copper spring that touches the spindle motor axis. Do not rotate the
step motor and do not oil anything else! And of course do not open the
drive unit itself.

Reassemble the profile but do not put the cover on it. Connect it to the
power line, switch it on and wait. 
After 18 seconds the stepper motor will move from its park position to
track 77, then to track 0. After that, a surface scan of the disk is
performed. You will see the step motor rotating slowly while the heads
travel from track to track. 
Sometimes the heads jump to track 77, then the scan continues. This
means a bad sector has been found. The drive does not access this
sector, it uses a spare sector instead. There are located on track 77,
32 are available.

Now watch the surface scan and count the number of movements towards the
spare track. A new drive uses 0..2 spares, 3..5 is means fine condition.
With more than 10 spare sectors used you should look for someone with
lowlevel formatting tools. 


The main problem: Information stored on magnetic disks fades after
several years. 
The data sectors are rewritten every time you store something on the
disk. But the address field headers are not. They were written in the
factory and never changed since then. If a couple of header bytes fail
the drive cannot locate the associated sectors and it assumes they are
bad. So you will get a lot of bad sectors reported, however your disk
surface is okay. Lowlevel formatting rewrites everything on the disk.


Patrick