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Help needed with Losmandy G11 Pmc8 System. #G11


Sunil Bhaskar Bhaskaran
 

Hi fellas,

                Been a while since I was last active in the forum. Hope everyone is doing well. To make a long story short, I seem to have run into a weird issue with my G11 mount. I just setup the mount today(after not using it for almost 8 months) and I immediately felt that there seems to be some friction build up when I was trying to balance the mount. While trying to perform drift alignment in phd2, the mount starts making weird whining/grinding noise not heard before. The mount used to guide perfectly fine before but now I am not sure what the issue is. To make things worse, I keep hearing a ticking sound(RA motor) when the mount is guiding. I am attaching two videos that can explain what I am facing. ANy help in this regard is greatly appreciated. 
Ticking noise : https://www.youtube.com/watch?v=ocDXVNyunOo&feature=youtu.be  ( That tick sound audio might be a bit low. Sorry abt that)
Whining/Grinding noise : https://www.youtube.com/watch?v=55iRuUrLitI&feature=youtu.be 

Has anyone experienced this before?

Sunil


Jennifer Shelly
 

Sunil:

Welcome back to the forum.  I have the same mount and I have not heard sounds like that before.  The squealing sound is the one I would be most concerned about. It sounds like parts are no longer lubricated and rubbing on each other.

You stated you had not used the mount in 8 months.  How did you have the mount stored? Was the mount inside or outside?  If the mount was outside was it exposed to humidity or rain?  If so you could have some rust.

Please describe what troubleshooting and/or inspections you have already done to determine the cause of the problems.  This way others may be able to chime in with some ideas and help you figure this out.
--
Sincerely,

Jennifer Shelly
AstroPorch, VA

Mounts
: ES PMC-8 G-11, ES PMC-8 iEXOS-100
Scopes: ES ED127 FCD-100, Askar FRA 400, ES Levy Comet Hunter, ES N208CF, QHY Mini Guide Scope, Solomark F60 Guide Scope
Cameras: QHY600M, QHY128C, QHY168C
Misc: MoonLite CFL 2.5 / High Res Stepper / V2 Mini Controller, Baader SteelTrack NT / SteelDrive II, Baader UFC, Optolong 2" L-Pro / L-eNhance, QHY CFW3-L, Baader 2” LRGBSHO CCD
Imaging Software:  NINA, APT, SharpCap Pro
Processing Software: PixInsight, Lightroom, Premiere Elements


Sunil Bhaskar Bhaskaran
 

Jennifer,

                 Thank you for your response. The Mount has been stored in a pelican 1650 case along with the Pmc8. The case has not been exposed to rain but humidity is a different story.  Most of my Apo's : Stellarvue 80 and ES 127mm FCD100 have developed fungus on the triplet lens.( Even though they themselves were kept in custom made cases). Weather has not been very cooperative over here for the last 6 months so never had the opportunity to fully test it. Yesterday when I finally did manage to boot it up, well you know the res :(. The mount was working perfectly fine before but that weird ticking sound was noticed first before the squealing noise became apparent. The only thing I have noticed is that during balancing both RA and Dec axis seems to be stiffer than usual : something I noticed 8 months ago but the mount worked fine then.The only adjustment I did was to tighten the Azimuth Locking knob as I felt it was too loose. The wavy washer is also installed so that can be discounted as the issue. These are the things I have observed overall : 
1) RA and Dec axis stiffness.
2)Azimuth "Adjustment" knobs seems to have a weird slipping issue : they seem to be very loose while adjusting(even with a 5 inch APO), especially during drift alignment proceedures.
3) Go to accuracy has always been questionable : This error might be more user related than mount but the mount almost always parks in the wrong position : the bubbles on the RA and Dec are not be centered. I use a workaround to avoid this issue.
4) The tick sound heard in the video occurs when most often when I am doing drift alignment procedure. Once I start imaging(SGP) , its gone.
5)  A lot of subs have been discarded by SGP because the the Dec corrections exceeded the specified limit in SGP( 20 px). 3 out of 5 frames are failing and SGP restarts the procedure.
6) THis is the first time I heard the squealing noise. THis was noticed only during "Parking" of the mount, no other time. WHen I park the mount from the meridian, this sound occurs. Rest of the time its perfectly fine.
7) Final point : the ticking sound seems to be coming from the RA motor where as the squealing seems to be coming from the saddle area.

Please let me know if you need any other info from my side.  
Sunil


Sunil Bhaskar Bhaskaran
 

One small correction on the 6th point in my post: The squealing noise is heard almost everytime I slew the mount.


Sunil Bhaskar Bhaskaran
 

Update : 

               Managed to fix most of the issues by taking apart and re-greasing the RA and DEC axis : the squealing noise was due to bad/solidified grease. But there seems to be RA & DEC play. Is there a manual or something available so that I can try to adjust the worms? I found the regular G11 manual but the design seems to be a bit different.

Sunil


Jennifer Shelly
 

Sunil:

Glad you figured out part of the problem was the grease.

Do you have the original worm and blocks or have you upgraded to the one piece worm block?  I assume you have the original worm and blocks.  If that is the case then adjusting these can be tricky because you have to loosen both blocks and keep even pressure while you pinch, pivot, and tighten the bolts up again.  This important because you want to make sure the blocks are square with one another and the pressure on the worm making contact with the bearings is enough so you will not have any side to side play.  

I suggest checking for side to side play before committing to the adjustment.  You will need the remove the top plate to expose the worm and blocks for each axis. Then with the clutches locked grab the counterweight bar and move it from side to side while watching the worm and the blocks.  If you see any side to side play then you will need to pinch both worm blocks with your fingers, slightly loosen the block that is farthest from the motor, pinch the blocks a little harder, and tighten the worm block.  Be careful not to shift the worm block up/down or twist.  Keep the block steady. Check again for side to side play.  If the side to side play is eliminated then that may be all you need to do.  If not repeat the process until the side to side play is eliminated.

If there is no side to side play then the worm is likely out of mesh with the wheel.  That involves slightly loosening both blocks while pinching them together, slightly pivoting the blocks upwards towards the side farthest from the motor, and tightening the worm blocks while holding and pinching the blocks.  You will wish you have three hands.  If you have someone who can help loosen and tighten the worm blocks for you that will save you from some frustration.  You will need to manually rotate the axis by hand to check for binding.  If any area of the manual rotation become difficult to do by hand then you will have to adjust your pivot downwards.  If it seems too easy to rotate by hand or if the worm seems too far from the wheel then you will have to adjust your pivot upwards.  You will likely have to do many iterations to get it right.

I hope this helps and good luck.
--
Sincerely,

Jennifer Shelly
AstroPorch, VA

Mounts
: ES PMC-8 G-11, ES PMC-8 iEXOS-100
Scopes: ES ED127 FCD-100, Askar FRA 400, ES Levy Comet Hunter, ES N208CF, QHY Mini Guide Scope, Solomark F60 Guide Scope
Cameras: QHY600M, QHY128C, QHY168C
Misc: MoonLite CFL 2.5 / High Res Stepper / V2 Mini Controller, Baader SteelTrack NT / SteelDrive II, Baader UFC, Optolong 2" L-Pro / L-eNhance, QHY CFW3-L, Baader 2” LRGBSHO CCD
Imaging Software:  NINA, APT, SharpCap Pro
Processing Software: PixInsight, Lightroom, Premiere Elements