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Subject: Re: [M]: LX200: 12" Drive Nightmare
From: Graham Warrellow
Reply To: mapug@shore.net
Date: Thu Jan 15 00:18:10 1998
In message , Dave Bair <hdbair@sun-link.com> writes
>Martin Mobberley wrote:
>>
>> As a new MAPUG member (joined today) I thought I'd waste no time and
>> immediately burden you all with my nightmare. (I have already had some
>> useful correspondence with Doc G).
>> I live in the UK (52d 10'N, 359d 14'W) and purchased a 12" LX200 + Wedge
>> back in August (via Meade's UK dealers). By early November the
>> observatory was completed and on the first possible night the LX200 went
>> on the wedge atop a concrete pier, powered by the 18V DC Meade supply.
>> Everything worked perfectly.....polar alignment, 5' slewing precision,
>> RS232 control via The SKY, the lot. Even the optics were good. This is a
>> superb instrument I thought; wait till my Xmas break with the new toy!
>> After weeks of cloud and various committments I went out complete with
>> (also new) an SBIG ST7 for the first night of CCD imaging. I connected up
>> the ST7 and switched the LX200 on. To my horror the scope started slewing
>> slowly to the West, unresponsive to the controls. There was nothing I
>> could do to stop it, and I tried everything.
<big snip>
Welcome to MAPUG. Sorry to read of your early experiences with your
LX200.
If I understand your account correctly, initially you used your 12"
LX200 visually (since August ?) without any problems; later you added
your ST-7, etc. and the problems began. Right? I'm not sure whether
the following thoughts apply to your situation as they are general
concerns and my observations of the reporting of motor failure on MAPUG.
I find it very interesting that the same people "seem" to have repeated
problems with motor burn outs and wonder if there is some common factor.
I think it would be very interesting to know whether those who have
experienced problems fail to balance their OTA's when adding extra loads
(extension tubes, cameras, CCD cameras, piggyback cameras, flip mirrors,
heavy eyepieces, OAG's, piggyback guidescopes, etc.) with a
consideration of the distance from the OTA's balance point.
I have always been very nervous of this in the past and reduced the slew
rate to minimise the initial motor load. However, to my mind this is
insufficient as it seems a lot to expect these small motors to survive
an out of balance OTA slewing to different areas of the sky with what
must be rapidly changing forces during rapid dec/RA movement. In my
case a counterweight system was one of my later purchases but now that I
have the Heapy 2-D counterweight system I quite happily load the OTA.
So far I've been lucky (?!) and after one year of regular use my 10"
LX200 has survived, but there is always the next session....:(((
Aren't those guys at BC&F great when it comes to sorting out a problem?
Good luck with your replacement LX200,
Regards,
Graham