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Re: G-5400B maintenance

Cliff and George give very sound advice!  I have found that sometimes the
pot in the rotor is okay, but the little rivets that lead the wiring out of
the pot are providing a poor connection.  A tiny bit of solder and a hot
iron can work wonders sometimes.


P.S. I also believe some of the pots are manufactured differently and what I
am suggesting does not apply to them.

> George and Alain:  George has the correct information.  Agreed getting
> ten years without entering the rotors is rather good.  You have the
> first indications of dirty rotor position pots.  After checking the
> connections, you maybe able to get a few more months out of the FODtrack
> interface board by putting a pair of capacitors on the board.  Locate U2
> which is the LM324 farthest away from the 7805 regulator.  Locate pins 2
> and 6 and then the 0.1 uFd capacitors connected to these pins.  At this
> point, on the opposite side where the components are mounted solder a
> physically small 0.1 uFd or so capacitor to ground in in both places.
> This will do two things:  First it will help bypass whatever RF is
> transferred down the rotor cable AND filter the "hash" created by the
> dirty position pot!  You may want to experiment with capacitor values by
> anything close is better than no capacitor at all.  Some time back there
> was a modification in which 750K resistors were suggested rather than
> one megohm across the existing 0.1 uFd caps, so do not panic if these
> values are in place!! The replacement potentiometer from Vertex Standard
> is part number Q9000408 and costs US about $30 dollars.    Cliff K7RR
> George Henry wrote:
> > The symptoms you describe could be from a dirty position potentiometer
> > in the rotor, from corroded or intermittent connections of the rotor
> > cable to the rotor, or from a break in the rotor cable where it is
> > secured to the mast/tower, from flexing over these many years.
> >
> > I would check the simplest thing first:  your rotor wire connections at
> > the rotor.  Pop the covers off and make sure that the wires or terminal
> > lugs are clean and the screws are tight, and that there is no corrosion
> > of the wire where it is crimped to the terminal lugs.  If all is okay
> > here, have someone watch the indicator while you shake the cables, to
> > test for breaks where you have secured them to your tower or mast.
> >
> > If none of these things help, then the position pot is likely at fault.
> > Replacements are available from Yaesu if you want to fix it yourself.
> > Yaesu charges $US70 per hour for repair if you want them to do it
> > (close to $US200 to completely overhaul them for you:  not a bad idea
> > after almost 10 years of service...)
> >
> > Hope this helps...
> >
> > 73 DE KA3HSW
> >
> >
> > ----- Original Message ----- From: "Alain De Carolis" <alain@alain.it>
> > To: <amsat-bb@amsat.org>
> > Sent: Saturday, April 16, 2005 11:31 AM
> > Subject: [amsat-bb] G-5400B maintenance
> >
> >
> >> Hello all,
> >>
> >> this might have been discussed before, anyhow I wasnt able to find the
> >> answer
> >> in the archives so here is my question for you.
> >> I have had my G-5400B in place since 1996 and I have never done any
> >> kind of
> >> maintenace since then.
> >> It works just fine, but it recently started giving me some troubles
> >> connected to my fodtrack interface.
> >> The problem is that the controller (or the rotor??) seem to give an
> >> instable
> >> indication of the azimuth. For just the fraction of a second the value
> >> titls
> >> a little bit and then returns normal.
> >> It happens when the rotor is in standby (rarely) and more often when
> >> it is
> >> rotating.
> >> It happens most often when I turn the az rotor and then turn the el
> >> rotor with
> >> the first one still going. The indicator vibrates a little and then
> >> return to
> >> normal course.
> >> This is not a big problem for manual operations but its the hell of a
> >> issue when using fodtrack. In facts, the automatic corrections done by
> >> the
> >> controller turn the system into a phisical oscillator that makes the az
> >> relays click like a machine-gun and the antenna array shake like if
> >> there is
> >> an earthquake.
> >> Do I need to clean something? Do I need to change some relay? Do I
> >> need to
> >> disassembly my rotors? What is the routine maintenance that I have
> >> probably
> >> missed?
> >>
> >> Thanks
> >>
> >> Alain De Carolis
> >> iz6byy ww3ww
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