[amsat-bb] Re: G-5500 Troubleshooting
jmeek at gaslightmedia.com
Sun May 2 17:55:00 PDT 2010
Ok Here's the reason for the apparent open winding in the AZ rotator motor.
The burned trace is severed, thus the open readings seen between Azimuth
6 and 4.
I'm pretty sure there were no snags or obstructions that could have
stopped rotation while powered.
I'm really lucky though, the fuse in the control box is undamaged ;-)
Thanks to Dom i8cvs for all the troubleshooting tips below. I will try
my hand at rebuilding this motor and use these tips to verify the work.
Thanks as always for the great information.
> ----- Original Message -----
> *From:* John Meeks <mailto:jmeek at gaslightmedia.com>
> *To:* i8cvs <mailto:domenico.i8cvs at tin.it>
> *Cc:* AMSAT-BB <mailto:amsat-bb at amsat.org>
> *Sent:* Sunday, May 02, 2010 11:17 PM
> *Subject:* Re: [amsat-bb] G-5500 Troubleshooting
> i8cvs wrote:
>> ----- Original Message -----
>> From: "John Meeks" <jmeek at gaslightmedia.com>
>> To: <amsat-bb at amsat.org>
>> Sent: Saturday, May 01, 2010 11:22 PM
>> Subject: [amsat-bb] G-5500 Troubleshooting
>>> One more thing... Given that the cable tested OK, what does the open
>>> reading from 6 to 4 suggest? My reading of the schematic diagram is
>>> sketchy at best.
>>> Any and all help will be greatly appreciated.
>>> John Meeks
>> Hi John, KC8ZFN
>> After the carefull troubleshooting you did and described the actual open
>> reading from 6 to 4 in the az. motor suggests two possible autcomes.
>> 1 ) The limit switch SW6 inside the rotator is defective and is an open
>> 2) The winding of the motor connected to limit switch SW6 is open
>> so that the motor cannot run nor left and nor right
>> Since 6 and 4 are an open circuit the electrolitic unpolarized capacitor
>> inside the motor appears to be not involved in this type of problem.
>> Please let me know just for curiosity the result of your investigation
>> but I believe that you have to open the azimuth rotator.
>> Best 73" de
>> i8CVS Domenico
> Thanks for confirming my conclusions so far, Dom.
> I've Got the Az rotator on the bench. It looks and smells new. The
> limit switches present a closed circuit until the swtich is
> activated when they open as expected.
> Looking for continuity between the pin corresponding to to A6
> (black wire) and one of the limit switches (red wires) shows 3.7
> ohms, and to the other switch (green wires) is an open circuit.
> I'm thinking this should be continuous also. If this is the case,
> what are my options? Has anyone had success repairing this motor?
> Thanks for the help.
> John Meeks
> Hi John, KC8ZFN
> Disconnect momentarely the electrolitic capacitor C34
> If the rotator is into an intermediate angular position the limit
> switches SW6 and SW7 are not activated and so they are in a
> normally close condition and must show a close circuit or zero ohm
> Looking for continuity between the common of the motor winding A6
> and directly to each end of both motor windings you must measure
> the same continuity with a resistance of 3.6 ohm
> In addition you must measure the continuity and 3.6 ohm between A6
> and both at the input and at the output of each limit switch SW6
> and SW7
> Measuring the resistance across each limit switch when the rotor
> is into an intermediate angular position you must measure zero ohm
> if SW6 and SW7 are OK since they are normally closed.
> If the limit switches SW6 and SW7 are OK then the motor winding
> showing an open circuit must be rewired because of a
> possible interruption somewere into the winding.
> Since you have the rotor over the working banch it should non be
> difficult to locate the interruption.
> If one motor windind must be rewired it is possible to rewind it
> by hand because there are not a great numbar of turns for 24 volt AC
> Please let me know.
> 73" de
> i8CVS Domenico
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