RD53 failure modes

[C Murillo-Sanchez]

On Mon, Feb 10, 2020 at 6:16 PM Fred Cisin via cctalk <cctalk at classiccmp.org>
wrote:

> On Fri, 7 Feb 2020, Carlos E Murillo-Sanchez via cctalk wrote:
> > system originally came with an RD53 that has sat elsewhere for 25
> years.  It
> > passed a read test in 2005.  So I tried to see if I could read it and
> maybe
> > image it now, but no go. The disk spins up, initiates a seek (the arm is
> not
> > stuck in a gooey stop pad; I've read that this is a common failure
> mechanism
> > for Micropolis 1325's; I opened it and saw the arm move) but then the
> arm
> > returns violently (clacking) to the rest position; it does this a number
> of
> > times (two to four, usually) and then it spins down. Applied voltages
> and
> > currents remain ok as this happens.
>
> If nobody speaks up who actually know anything about them, . . .
>
> Q: Is the return to the reset position more violent than the usual return?
> If it is not different, then consider the possibility of something not
> related to positioner, such as: seek to track, try to READ, FAIL, reset,
> REPEAT.  In which case, it could be anything that caused the read to fail,
> such as head problems, failing to find the servo data, . . .
>

Sorry for not replying earlier, your message made it to the spam folder.
The return is more violent than the usual return.  I put a piece of paper
between the arm stop and the arm, and this did not modify the behavior.  I
am now inclined to think that it is failing to find the servo data.

carlos.