----- 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