----- Original Message ----- From: "PE0SAT" <[email protected]> To: "i8cvs" <[email protected]> Cc: "AMSAT-BB" <[email protected]> Sent: Tuesday, August 25, 2009 9:38 PM Subject: Re: [amsat-bb] Azimute pointer on a G-5600 gives a wrong value > > On Tue, August 25, 2009 19:45, i8cvs wrote: > > > > Connect a voltmeter between terminals A1 and A3 of the control box > > The voltage across the 500 ohm potentiometer into the azimuth rotator > > must remain constant at about 6 volt while turning the azimuth.
> > 73" de i8CVS Domenico > Hi Domenico, > > As allways you give great answers :)) > > There is 9.2 volt DC :( looks that the 7806 is defect. But one thing > that puzzles me, i don't see a connection from the negative site of the > ac-dc diode bridge to ground. > > 73's Jan > Hi Jan, PE0SAT OK the 7806 is defective and must be changed but since you have to open the controller of G-5600 I suggest you to improve the regulator performance because the original capacitor C9 0.01 uF at the regulator output is a very small bypass capacitor. Solder a ceramic capacitor of 0.1 uF in parallel to an electrolitic capacitor ranging from 1 to 10 uF and solder it both at the input and as well at the output of the regulator as this cure will prevent possible autoscillations of the regulator itself in a wide frequency band. The negative path of the bridge to ground for the regulator Q2 is through series diodes D5-D4-D3 and ground so that a drop of about 0.6 x 3 = 1.8 volt is developed and this is made to get a minimum voltage of 1.8 volt and not 0 volt when the wiper of the 500 ohm potentiometer is fully grounded. The negative path of the bridge to ground for B1 C1 and B2 C2 to supply the +/- voltages to the operational amplifiers is through the series transistor Q1 and zener diode D2 The negative path of the bridge for the coils of relay RY1-RY2-RY3 and RY4 is directly connected floating to the bridge and insulated from the ground. Have fun and 73" de i8CVS Domenico _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
