Hemisphere switch

[LewisM]

Looking at purchasing an older Takahashi mount, that does not have a N/S hemisphere switch, and is a northern hem. mount.

Can I merely reverse motor polarity to use here, or are there other considerations?

Thanks.

[casstony]

You'd probably kill other electronic components, though I'm not familiar with Tak electronics.

[LewisM]

That is my concern. It is RA drive only though.

[Joshua Bunn (Joshua)]

You would also have to change the Dec drive if im not mistaken... yes?

Josh

[LewisM]

There is no dec drive. RA only. I am talking a 20 year old mount here

[Joshua Bunn (Joshua)]

I see.

[alocky (Andrew lockwood)]

On my old unitrons you change hemisphere by mounting the motor on the other end of the worm.

[bojan]

Just reverse the motor.
And, align with Polaris, not with Sigma Oct.

[Irish stargazer (John)]

From memory, my old Meade 2080B SCT had a synchronous motor (AC) I think . I had to replace the base and was lucky to find one from someone demounting their OTA.
I presume this mount is a DC one??

[Hans Tucker (Hans)]

Originally Posted by LewisM

Looking at purchasing an older Takahashi mount, that does not have a N/S hemisphere switch, and is a northern hem. mount.

Can I merely reverse motor polarity to use here, or are there other considerations?

Thanks.

I got to admit this has me perplexed and interested. What model of mount are you buying...EM100, EM-1S. I really thought that all Takahashi Mounts were useable in both hemispheres..this is the first time I have come across a Northern Hemisphere mount.

[LewisM]

EM-1S. Seller says there is no button or switch or whatever to reverse RA direction, and I thought just to reverse polarity.

The mount is an old one. VERY rudimentary.

[Kunama]

Lewis, you might send a PM to Lars. He had one years ago that he sold on IIS.

[Hans Tucker (Hans)]

Originally Posted by LewisM

EM-1S. Seller says there is no button or switch or whatever to reverse RA direction, and I thought just to reverse polarity.

The mount is an old one. VERY rudimentary.

Looking at the Operators Manual for the EM-1S I doubt you will do any damage if you do as you, and others, have suggested and switch the motor leads to run in reverse.

[raymo]

I know nothing about Takahashi specifically, but if the R.A. drive is a simple on/off switch, all you have to do is reverse the polarity as you suggest,
and then use it as normal.[this assumes that it uses a D.C. motor, not mains voltage A.C. like my Celestron C8.]

Where the only problem could lie is if the R.A. control is a hand
controller that has the ability to vary the drive speed, or any other
possible function; in which case it will almost certainly contain a diode,
which will burn out if the polarity is reversed. You can prevent this
happening by switching the diode to the other cable, so the current is still
passing through the diode in the original direction.
Hope this helps
raymo

[skysurfer]

Is there not a direction switch on the controller ?
I have a 22 year old RA motor controller of the Vixen SP mount and it has a switch 1 <=> 2 where 1 = south and 2 is north and works great.
Maybe there is such a switch on your handcontroller ?

[Hans Tucker (Hans)]

I found an ad on Astromart for a Takahashi EM-1S. Lewis, you might want to look at point 3 in Questions Answered in Advanced.

http://www.astromart.com/classifieds...fied_id=532662

Looks like the switch you are looking for may be inside the hand controller on the circuit board.

[Barrykgerdes]

If you are looking at an old EQ mount that only has an analogue or simple digital speed control what is the point of retaining it. If the mount is good and has good mechanics a later drive system could be considered.

In any case reversing the motor direction should be no bother if there is no switch. Most AC or DC motors can be reversed quite simply with a wire change.

Barry

[PRejto (Peter)]

If the motor is a synchronous motor reversing the polarity will not work. The motor will still turn in the same direction.

If the motor is synchronous there is a solution - providing you can find the room and a mounting solution - by just adding a small gear between the motor gear and the worm gear. The size does not matter. Just the teeth need to mesh properly. The additional gear will cause the mount to track in the reverse direction at the original speed. I did this to an old Cave Astrola mount and it worked perfectly. However, these mounts are usually designed for 60hz current. They run at 50hz but too slowly so you then need to build up a frequency generator and that is a can of worms to say the least.

Peter

[LewisM]

I have decided NOT to go with the Tak mount, as tempting as it is.

Thanks for the replies guys.