from  George Koenig koenig@ifa.hawaii.edu
     to  irtftechgroup@ifa.hawaii.edu
   date  Tue, Aug 9, 2011 at 3:41 PM
subject  HA Servo Tachometer brush assy.
   
Hi,
    When cleaning the tachs today I had to replace the West side motor tachometer
on the HA drive motors.  The brush fingers were worn down to the point where they
fell apart when touched.  They were also heavly gunked with oil-carbon.
    The other tachs looked normal with the one inside the west yoke looking new and
with no oil-carbon buildup.  I removed all but the inside west yoke as an assy with
the connector attached so I could redo the wiring to the connector with shrink tube.
The black wire on the East side HA motor had some cuts to the insulation where it
was pinched at sometime ago. I cut off the pinched section and resoldered with shrink
tubing.  I also had Maury clean the HA bullgear while I was working on the tachs.
The Dec bullgear has a limited opening to get to so we need to remove a bottom plate
when we have time in order to clean the dec bullgear better.  We should also look into
replacing the cleaning erasers on the bullgears if we can find some new felt erasers to
cut up.
    I also checked and altered the balance for the pointing run.

-- 
thanks,
-George

  George Koenig  ~  Observatory Superintendent  ~  NASA Infrared Telescope
Institute for Astronomy-IRTF  ~  640 N. A'ohoku Pl. Rm.209  ~  Hilo, HI 96720
                           808-974-4209  ~   koenig@ifa.hawaii.edu