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Takahashi Mounts - 12v or 24 v

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#1 BarrySimon615

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Posted 25 August 2009 - 09:49 AM

Many Takahashi mounts - EM10, EM11, EM200, EM400, will run on either 12v or 24v. Slewing is approximately twice as fast at 24v. I find that if a battery drops much below 12v (12v 18amp hr sealed lead acid) the fast slewing stops first in dec., followed by RA. So I may consider hooking up two batteries to get 24v and faster slew speeds and presumably longer run times assuming the amperage stays up near 18 as the voltage drops off. This leads me to my question - does anyone know if the Takahashi mounts are set up in such a way that the voltage has to be at or very near 24v or at or very near 12v for proper operation. What if anything would happen if the voltage were to be say 20v, 18v, 16v? Would the mount still operate normally but with perhaps somewhat slower slew speeds than what can be obtained at 24v?

Barry Simon

#2 tim53

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Posted 25 August 2009 - 12:35 PM

Barry:

I would think that the mount would work fine until the voltage dropped much below 12V (though slews might be slower than up around 24V).

My 2000 NJP Temma PC started having problems slewing off my car battery when I used Voyager 4.5 for scope control. Voyager tried to slew both axes at the same time, which worked for about 45 degrees of sky, then I got a tone from the mount and the slewing stopped. When I slewed manually with the HC, I slewed one axis at a time and had no further problems.

Not that you're likely to encounter this problem, but be forewarned that older Tak mounts are 12V only - at least my 1993 EM-500 is. I didn't know this and the seller didn't have a power supply for it, so I plugged it into my 24V inverter and fried an IC on the board. I've since upgraded it to a Sidereal Technology servo goto.

-Tim.

#3 skyler

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Posted 25 August 2009 - 05:54 PM

HI Tim -

How difficult was that retrofit on the EM500 and are you still running 12 vdc?

S

#4 Tim C

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Posted 25 August 2009 - 06:16 PM

Just an fyi - the latest EM200 that was just introduced on the Takahashi Japan website(Temma EM200M I think it's called) runs on 12 volts - you don't need the 24 volts for the faster slew speeds. Got an updated hand controller as well.

#5 Dwight J

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Posted 25 August 2009 - 07:48 PM

Hi Barry: I have found my em 200 also doesn't autoguide if the voltage falls below 12 volts. I don't mind the slower slew speed at 12 volts as it is not that slow. I have a second battery (both are 35 amp hr gel cells)as back up. I observed over 3 nights using the slewing and the first battery was still holding up at 70% charge and putting out 12.5 volts.

#6 tim53

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Posted 25 August 2009 - 07:50 PM

skyler:

Adapting the Sitech to the Em-500 was very easy. It's a big mount, so there's lots of room there. I even used the original spur gears, but I did have to machine some very small bushings to mate the larger metric holes in the gears to the smaller english shafts of the pittman motors. I turned them out of brass bar stock and left a step on them to help support and center them when I used the tailstock to press the Tak gears onto them, then cut them off the bar stock with the whole setup still mounted in the lathe.

I posted pix of the conversion on the SiTech yahoo photo page.

I'm running the Sitech rig with 12 volts, but I imagine I could use the 24V inverter from TN, as it's supposed to be able to run on 24V too.

-Tim.






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