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Subject: playback issues, Less vibration sensitive HD
From: Carmen Lams & Peter Verbeke (peterverbeke_at_bigfoot.com)
Date: 2004-06-15


hi,

Some sharing of experiences and a quick question:

 From the web site it appears that quite a lot of users have been having
trouble with playback (freeze, appears to play but no sound, HD
continuously on). I am using my archos on the motor bike and previously on
the train and have experienced all of the above recently. Below I just
wanted to share my experiences.
First I suspected something was wrong with the Hard disk and tried a
scandisk: it turned out there were some errors on the disk it could not
repair. after a reformat and another check with scandisk including a
partial surface scan I was fairly certain that all was ok (although I still
don't know why I got some of the unrecoverable errors). Some further
use showed a marked decrease in playback problems but the issue was not
resolved completely. After reading Chris Hasall's page I opened up my unit
discovered several areas of concern including loose soldering points and a
possible short. I re-soldered the points and made use of shrink film to
insulate. Again the regularity of playback stops reduced and way in which
the jukebox stopped playing reduced to one mechanism only: when subjected
to vibration (read making good progress on a motorbike on the motorway)
playback usually started to be erratic i.e. start stop and in some
occasions stopped completely. On inspection of the unit the HD red led is
on and the harddisk is spinning with the heads obviously moving around. The
rockbox is waiting patiently for input.

Some further experimentation at home with the unit gave me some insight in
the failure mechanism. On "shaking" the unit just before or during a read
operation gently the HD seems to be unable to read or figures out there is
vibration (understand the Hitachi has a smart system to detect this) and
waits until the shaking is over to get the required data. In the mean time
the Rockbox waits. When one shakes more vigorously on some occasions one
hears the heads moving, I suspect some protection by the disk against
damage. Under those circumstances the unit, usually on the next read
operation (even without further shaking) seems to fail in most cases to get
the required data and keeps on looking and playback stops. Even more
vigorous shaking can lead to the rockbox seemingly continuing to play
without sound. On the next read however the unit recovers and continues
playing.

Although all not very scientific it turns out that the playback errors seem
to be related to disk errors, loose contacts and shorts and finally on the
HD sensitivity to vibration, which brings me to my question: Does anybody
have any experience with other drives that are a bit more robust with
regards to vibration? are some of the more modern drives with higher
rotational speed and lager buffers better or not? I would hate to spend 70
pounds (UK) on a new drive to end up with the same problem.

As far as the rockbox goes Fantastic stuff and possibly the software could
also help with the sensitive Hitachi: If one could track the time the HD is
taking to deliver a new block of data one could decide to reset the HD and
try again instead of patiently waiting around. Have not looked at the
sources, nor am I an expert, it's just an idea....

Peter Verbeke


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