[AZ-Observing] Cable Gone Out
- From: Stan Gorodenski <stanlep@xxxxxxxxxxxxx>
- To: AZ-Observing <az-observing@xxxxxxxxxxxxx>
- Date: Mon, 27 Jul 2009 13:44:00 -0700
Not too long ago someone had an issue with a Meade telescope acting
unpredictably. I suggested check the cable from the mount to the
handpaddle. I had the same problem with my Meade LXD75 10". I replaced
the cable and it worked fine. I just now had the same problem with my
16" LX200R, but it happened at a bad time, causing me to be concerned
that something more serious was going on with the circuit boards in the
telescope. Thank goodness, that was not the case.
I had just finished replacing the Dec motor. I bought this from Meade
directly last year because I thought the dec motor was bad, but wasn't
sure. Recently, I concluded definitely it is and so I just now replaced
it. This involved taking out the worm gear and the housing that holds
the worm to also check them out while I am at it. I finally got
everything together around noon today and everything seemed to be
working good. The dec motor was working properly. I was getting ready to
train the telescope using a century plant on top of one of the hills to
the west of me. I went in the house for something and when I got back
the screen on the handpaddle was blank. It is supposed to go blank out
when it is unused for some time, but when I pressed a key to bring it
back up sometimes it came up and sometimes it didn't. The motion buttons
sometimes worked and sometimes didn't, and one time it kept slewing
after I released the button. I had to quickly turn the telescope off.
When I would bring it back up the handpaddle screen would sometimes be
good part of the time, but a lot of the times it just flickered with a
glow. I thought, great, just what I need. To have a circuit board go
bad, possibly from something wrong with the dec motor I just installed
or some mistake I made soldering the wires together and wrapping the
excess lengths of wire around the tubular ceramic magnet, although this
was so simple I could not see how.
I know that the handpaddle is a weak point in the telescope system and
so about a year ago I bought another handpaddle as a spare. It came with
another cable. So I checked the old cable with the new one. After
repeated switching between the two and pulling here and there, I
discovered the cable end that goes into the handpaddle is bad. If I
pulled on it, the handpaddle would go blank. I looked at the cable under
my binocular microscope and saw that the cable is very firmly held in
place in the plastic clip and so it had not pulled out. Apparently, what
has happened is that over time the flexure at the point where it goes
into the handpaddle had internally broken one or more wires. I wish
there was some way to prevent the cable from twisting sometimes at
almost a 90 degree angle during normal use. I am sure this kind of
flexure is what caused it to go bad.
Stan
--
"If people knew how hard I had to work to gain my
mastery, it would not seem so wonderful at all" - Michelangelo
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