On 11/02/2012 04:33, David Farber wrote:

Hi Andrew,

I have the LS-2000 scanner. I had some scanning troubles with mine as well
though I can't remember if screeching noises was one of the symptoms. Not
only did I clean and lube the rails, I removed anything in the transport
that moved and made sure nothing was sticking. I think you'll need to remove
that plastic pulley shown on page 6 of your pdf and make sure that isn't
sticking as well.

Well, I got a chance to do some more tests at the weekend. Basically
there appear to be three [1] speeds at which the carriage can move,
Fast, medium or slow. It moves on rails between the front (F) and back
(B) of the unit.

On power on:

F-B fast - lots of power
B-F fast - to home position lots of power

On preview:

B-F medium - preview scan, lots of power
F-B fast - return to home position, can be stopped with a finger

On scan:
B-F slow - scanning, lots of power
F-B fast - return to home position, can be stopped with a finger

So it seems that the power that the carriage has is not related to how
fast it is going but how fast it has been going. These tests were all
done with the spring removed so no interference on that front.

I am at a loss to see a connection between speed and power unless there
is micro-stepping involved in the preview/scan which leaves the motor in
a position where the return is underpowered. But what would be the root
cause?

Does the team have any further ideas of where to look next?

Thanks for everyone's input.

Andrew

[1] specifically there is a range of speeds depending on the
preview/scan resolution selected.