The motors (SAIA or Hurst) operate on 12V – the regulator is just there for the digital stuff. The Darlington transistor array (the 18 pin DIP at the top of the PCB) is connected directly to the 12V line, before the regulator.

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The electronics of the 492 are pretty simple (although if they re-engineered it with modern parts it would only have two chips). So unless the unit is really old (mine has the 2006 sticker on it) I wouldn’t worry about that. In a few more decades maybe you’ll have to worry about capacitors.

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The grease in the motors should be good to much colder temperatures than you’ll ever see in CA – I’ve used my 492 system in Northern Illinois for years and we get down to -20F from time to time. That is -29C. Then the operator is the problem, not the mount.

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And at half-stepping I have never seen a problem even with lunar imaging at 2800mm+ focal length and 2 micron pixels.

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The Hurst (now NiDec) motor specs say -10 to +40C (approximate) and don’t forget that the motors generate their own heat, although only ? watt per the label. Not a lot of power but it is in a confined space. Starting from a cold soak is another matter but, again, I’ve never seen a problem in practice. Hurst, after all, is in Northern Indiana, not California or Shanghai. We’re not sunbathers around here.

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So I wouldn’t go messing with the motors until after everything else (mesh of gears, bearing and axel grease, connectors, batteries) were checked out. Opening up the cases is a bad idea to my mind. If I did that I’d be ready to buy new ones in case I screwed it up.

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As to batteries, well, the Lithium composite cited is not recommended for storage below freezing. Operating (where it generates its own heat) they are rated down to -4C (not as good as the motors for what that is worth – you never know how much engineering margin is being applied) and will lose 20 to 40 percent of the capacity as a function of on the discharge history at -20C depending on whose research you read.

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So I’m sticking with lead acid for now, personally.

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But I’d look at the mesh and mount grease plus connectors (ugh, who decided modular phone jacks were a good idea for field equipment?)? and ?cables, then the batteries. The motors? The last thing I’d look at. Could be, of course.

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Happy Holidays,

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Mark Christensen