Re: [APML] ST-4 HELP (!!!!) needed...

["Eddie Guscott" <eddie.guscott@blueyonder.co.uk>]

John

If you're brave enough, open the back of the ST4 relay box and see if any of
the 4 relay chips are loose. Try re-seating all of them.

I had a similar problem recently, and the fault was these loose relay chips
caused by excessive transport in back of the car.

This cured the problem completely

Eddie Guscott

----- Original Message ----- 
From: "John Lanoue" <johnlanoue@hotmail.com>
To: <astro-photo@seds.org>
Sent: Sunday, November 16, 2003 2:08 PM
Subject: [APML] ST-4 HELP (!!!!) needed...


> Greetings,
>
> I missed out on 5 good hours of imaging last night because my st-4
wouldn't
> calibrate and I'm wondering if anyone else has seen this problem.  This
may
> be a continuation of my 'aurora' problems from two weeks back, I don't
know.
>
> Problem:
> The ST-4, when calibrating (depending on the orientation of the CCD head)
> will do the following four movements, increase x by C0 seconds, decrease x
> by C0 seconds, increase y by C1 seconds and decrease y by C1 seconds, for
> shorthand sake, I'll call these four steps +x, -x, +y and -y.  I have the
> head oriented such that x corresponds to RA and y corresponds to Dec.
What
> I'm seeing is the +y step results in no change in y (on the ST-4 readout)
> and the -y step results in y incrementing (like you would expect it to do
in
> the +y step).
>
> That's the jist of the problem, but here's more...
>
> Using the lx200 hand controller, in guide mode, I can move the scope in x
> and y (such that the display increments and decrements on the st-4).  So I
> believe that eliminates the lx200 drive as the source of the problem.
Also,
> it doesn't matter what I increase C1 to, on my scope, a value of C0=C1=3
has
> worked fine in the past (I'm guiding at prime focus of a 12" lx200), I
upped
> C1 to 10 seconds and it made no difference in the third step, the +y step
> still resulted in zero movement.  Also, during the failed third step, the
> scope is making no noise, and I've always been able to tell when it's
moving
> in declination.  I can clearly hear it moving when it's doing the -y step
> (which turns out moving the scope in the +y direction).  And finally, not
> that it matters for calibration, but I set SA to 10 to turn it off.  Also,
> my drive has a bit of backlash, what lx200 doesn't?  However, it's never
> been a problem, but regardless, I messed around with H1 (hysterisis-y) and
> it made no difference.
>
> Oh, one last thing... (I know, I sound like columbo), if I disconnect the
> ST-4 from the lx200 control panel during calibration and using the audible
> clues of the st-4, manually press the N/S/E/W keys to emulate the
> calibration sequence, then believe it or not, the calibration succeeds and
I
> can track.  What this points out is that in track mode, it appears that
the
> st-4 can issue declination corrections (declination=y).  I say appears
> because I have a pretty good polar alignment, so its possible that no
> corrections were needed.
>
> I can't help but think this is a cabling issue... anyone out there seen
this
> or want to take a guess?  If you want to contact me off list and/or speak
> over the phone, that would be great.  I would love to get out tonight if
> possible.
>
> John
>
>
>
> John Lanoue
> Principal Software Engineer
> Bedford, NH
> http://www.geocities.com/johnlanoue/
>
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