Re: DEC Motor stalls on new Mach2GTO

Luca Marinelli

Thanks a lot for the quick reply, Roland. I am pretty sure I mounted the dovetail with the arrow pointing forward. The USB and power port are in the back of the scope, not on the side. See the attached picture.

Also, both N and S movements result in motor stalls, not just in one direction.

Thanks again,


On Dec 26, 2020, at 8:01 PM, Roland Christen via <chris1011@...> wrote:

It sounds like you are hitting the internal hard limit. You probably have the scope mounted at 90 degrees from the arrow on the top of the Dec mounting plate. Remove your scope and dovetail and look at the mounting plate. You will se a long arrow. This is the direction that your scope must point. You cannot mount it at 90 degrees or you simply run out of Dec motion when pointing south and the axis will hit the hard stop and the motors will stall with yellow light coming on.

Can you post a picture showing the scope pointing at the north pole?

Roland Christen
Astro-Physics Inc.

-----Original Message-----
From: Luca Marinelli <photo@...>
Sent: Sat, Dec 26, 2020 6:16 pm
Subject: [ap-gto] DEC Motor stalls on new Mach2GTO

Today I replaced the Mach1 in the observatory with the new Mach2 I received a few days ago. I have a Tak FSQ106 mounted on the Mach2 and it balanced without any problems. I tested a slew and everything worked fine. I then started to set up the Meridian limit in APCC Pro and after sending the scope to the Southern horizon (-15 degrees DEC) I started experiencing motor stalls. The mount makes a whirring/grinding noise when trying to slew in DEC and APCC communication window shows motor stall condition. The light on the CP5 turns amber. I measured the voltage out of the power supply and it is correct (24.94V). I also replaced the power supply with the power supply i used with the Mach1 and the same thing happened. To test the motor cable, I swapped DEC and RA cables and the fault was still on the DEC axis. I removed the telescope and tried slewing the empty mount in DEC, to no avail (motor stalls). 

APCC Pro version:
CP5 firmware: VCP5-P02-08
Encoder version: A02-08

Is there anything obvious I am missing?



Roland Christen

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