[amsat-bb] Re: G-5500 Troubleshooting

[John Meeks]

Ok Here's the reason for the apparent open winding in the AZ rotator motor.
http://picasaweb.google.com/vanagon/YaesuG5500AntennaRotator 
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.

John Meeks
KC8ZFN

i8cvs wrote:
>
>     ----- 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
>>>     KC8ZFN
>>>         
>>
>>     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
>>           circuit
>>
>>     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
>     KC8ZFN
>      
>
>     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  
>
>
>        
>