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Re: G-5400B maintenance



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 when
>> 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 big
>> 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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