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PENTAX MS-55z Musical Mount

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5 replies to this topic

#1 Michaeljhogan

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Posted 23 January 2020 - 01:56 PM

 It would drive me crazy but id say its goto,s are insanely accurate grin.gif

 

https://www.youtube....h?v=_f4P8mTlGtI


Edited by Michaeljhogan, 23 January 2020 - 05:54 PM.

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#2 petert913

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Posted 23 January 2020 - 03:19 PM

What's with the Japanese gear and the color green ?  laugh.gif



#3 Michaeljhogan

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Posted 23 January 2020 - 05:50 PM

What's with the Japanese gear and the color green ?  laugh.gif

Bro i heard that the mount is from 1992 to 1997 the quality looks like it could last 100 years its already lasted 25 or more


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#4 Stephen Kennedy

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Posted 24 January 2020 - 03:15 AM

This is my Pentax MS-5 GEM which I purchased new in 1988 while stationed in Japan:

 

IMG_1168 (3).JPG

 

It has been running without any problems for 32 years.  Unfortunately, it is not goto and was the predecsecor   of the MS-55.  It has a mass of 145 kg and is carrying a 23 kg Mikage 210 mm F/7.7 Newtonian reflector OTA.  This GEM has a PE of < 2" but is not equipped with PEC.  These massive Pentax GEMs may have been the best amateur mounts ever made and will easily last 100 years.  It is a real shame that when Ricoh purchased Pentax and ended production of all astronomical  product except for eyepieces.  A 2020 Pentax MS GEM would be the best GEM money could be, but would require a lot of money to buy one,


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#5 orlyandico

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Posted 24 January 2020 - 01:16 PM

Stephen,

 

The singing noises made by that MS-55 GoTo conversion are due to harmonics due to the stepper motor drivers. Notice that they happen during ramping activity, but when the motors are running at constant speed the singing is much less obvious.

 

I suspect that the original motors are being used. With modern stepper motor drivers like the Trinamic SilentStepStick, even these old low-PPR, high gear reduction steppers can be run at a decent speed. So it is possible to do a completely reversible GoTo conversion without touching the mechanicals of the mount at all.

 

This is the reason I've been saying you can convert that MS-5 of yours to GoTo for a very reasonable price.  George (https://www.cloudyni...user/55410-geo/) I think is selling fully assembled OnStep kits now. You may want to ask him..


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#6 Michaeljhogan

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Posted 24 January 2020 - 03:00 PM

Stephen,

 

The singing noises made by that MS-55 GoTo conversion are due to harmonics due to the stepper motor drivers. Notice that they happen during ramping activity, but when the motors are running at constant speed the singing is much less obvious.

 

I suspect that the original motors are being used. With modern stepper motor drivers like the Trinamic SilentStepStick, even these old low-PPR, high gear reduction steppers can be run at a decent speed. So it is possible to do a completely reversible GoTo conversion without touching the mechanicals of the mount at all.

 

This is the reason I've been saying you can convert that MS-5 of yours to GoTo for a very reasonable price.  George (https://www.cloudyni...user/55410-geo/) I think is selling fully assembled OnStep kits now. You may want to ask him..

https://www.freego2....ery/video-items FreeGo2 being used on the new OGEM mount

 

https://www.youtube....h?v=EvoG5W_g9xs


Edited by Michaeljhogan, 24 January 2020 - 03:08 PM.

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