Paramount MX Maintenance

I’ve been planning this for about two, maybe three weeks.  After I received the correct grease from America, I figured that with the weekend shaping up to be wet, windy and pointless for viewing, this would be a good time to get-to and finish maintaining the Paramount MX inside SkySlab.  This sounds like a risky task – given the cost of the mount – but after watching some videos, reading the instructions (which you can access if you are a paid subscriber to Software Bisque) and discussing it briefly on IceInSpace, I was confident enough to do this without calling on Software Bisque for help.

Before I go into the detail, the end result has been good I think.  I’ve re-greased both axis of the mount, taken the worm drives off, made sure the belts are the kevlar reinforced grey ones and put it all back together.  The only thing I’m not sure about was adjusting the cam shaft lock.  I did this but am not sure about how tightly the lock screws (not the grub screws, the button screws) need to be.  It’s an easy thing to re-adjust if all else fails and if the PEC curve or mount performance suffers.  This needs to be tested – which will happen in the next few weeks.

Here’s the detail

Steps (sub-steps are indented)Picture
Remove the base plate from the mount.
This should end up looking like this.
As part of this step, you have to remove the part with the USB connections and stuff (I forget what it's called) from the base plate, I've used some electrical tape to keep this neatly attached while I do the maintenance.
The base plate once removed looks like this.
I prefer to keep my nuts, bolts and stuff separated into containers - stops me from mixing them up or loosing them.
Undo the bolts on the four corners of the RA drive cover - not the center one, leave that facing the 'Balance' graphic (mine is facing lock, that's the wrong position, I moved it to balance before removing the drive cover).
Here you can see the bolts that I am removing raised slightly.
Once the cover is removed, you'll see the drive (notice the grey belt, it should be grey and not black).
And here's the cover sitting pretty.
Here's all the bolts that have been removed so far.
Now you need to remove the motor drive (the video is important in showing how to do that).
Here's the motor taped into place to stop it swinging anywhere while I perform maintenance.
Here's what the drive looks like with the motor removed.
After taping up the holes in the mount with electrical tape, you then remove the drive itself. I found it easiest to remove the two larger bolts first, then the two smaller ones.
Here's what the mount looks like with the drive removed.
Here's what the drive looks like.
Clean the teeth of the drive plate and the drive itself with a cloth and stiff paint brush, turning the cloth frequently and using the brush to get the grease out of the teeth.Didn't take a picture of this.
Re-grease both the drive plate and the drive with the recommended grease.
Here's the drive plate re-greased (note the electrical tape covering the holes in the mount to stop bolts falling through the mount).
Here's the drive re-greased.
Now put the drive back on the mount. I found it easier to start with the two smaller bolts at the top of the drive, then the two larger ones at the bottom of the drive.
The put the drive motor back in and tension the drive belt.
I've tensioned the drive belt fairly tightly here, but you can still push the belt inwards a bit with a finger - so it's not stretching the drive belt.
Now you have to re-tension the cam-shaft by loosening the bolt with a button head (not the grub screw above it) and pressing the middle bolt down as far as it will go.
The video will show more detail on how you actually tension the shaft, then do-up the bolt again after the drive case is re-attached during the process.No pictures of this, the video describes it very well.
Put the drive casing back on and that's it, done.Pictures above show the drive casing nicely.
Now on to the DEC drive.
Here's the cover removed.
Again, I've taped the hole in the mount to stop anything falling through it and here's the gear plate uncleaned.
Here's the DEC drive uncleaned.
Just as I did with the RA drive, I cleaned and re-greased both the drive plate and the worm drive. Then put it back together, re-tensioned the drive belt and the cam-shaft.
Finally, gave the mount a wipe over, air-dusted the electronic components and visually inspected so check for any wear on the circuit boards. Put those back and set to exercising the mount.

Here’s a video of the mount after maintenance being exercised

What’s next (when weather and time permit)?

  1. Put a scope on the mount;
  2. Get the imaging train right;
  3. Collimate and focus;
  4. Do a 300 t-point run;
  5. Check polar alignment;
  6. Probably do some modifications based on the polar alignment;
  7. Do another 300 t-point run;
  8. Hopefully that will be ok, otherwise rinse and repeat from step 5 until the polar alignment report tells me it’s close enough;
  9. Check collimation and focus again;
  10. Take some photos (!!).

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