----- Original Message ----- From: "Michael J. Wolthuis" wolthui3@msu.edu To: "Elan Portnoy" elanportnoy@yahoo.com Cc: amsat-bb@amsat.org Sent: Monday, November 23, 2009 2:07 AM Subject: [amsat-bb] Re: Help with Yaesu g5500
Not the switch unfortunately. The same problem occurs when controlled by computer from Uni_trac 2000. Work about 25% of the time.
Mike kb8zgl
Hi Mike, KB8ZGL
Connect an AC voltmeter between A4 and A5 on rear of control box and check if there is 24 volt AC when the rotator sticks.
If you have 24 volts when the rotator sticks connect an amperometer in series with A4 or with A5 and check if the AC current flows as soon the rotator sticks.
If the current flows when the rotator sticks probably the internal AC 100 uF capacitor is defective or you have a mechanical problem inside the reduction gear or into the ball bearing holder of your rotator
If you have a 100 uF AC capacitor in the junk box connect it across A4 and A5 and try again to see the effect.
If you don't have an AC capacitor you can buit it by your self using two electrolitic capacitors each 200 uF 250 volt DC and two diode 1N4007 or equivalent connected as per the following schematic diagram:
- + + - |--------) |------|------| (--------| A4-----| | |-------A5 |-------|>|------|------|<|--------| 1N4007 1N4007
If the rotator sticks and if the AC current don't flow you probably have e limit switch SW6 or SW7 defective "poor contact and high resistivity" between contacts.
Disconnect A4 and A5 from control box and using an ohm-meter check the continuity of the motor windings
If one winding of the motor has a fail contact then your ohm-meter will jump measuring the capacity of the AC capacitor.
This is what I would do easy and fast in your situation.
Have fun
73" de
i8CVS Domenico