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johngwheeler
09-08-2016, 06:25 AM
I'm looking at a used Takahashi EM-200 Temma 2 mount (not the 2M) and noticed a problem with the polar scope illuminated reticle. Although there is a red light visible inside the mount casing (when looking through the front of the polar scope aperture), nothing was visible through the p-scope itself, and the reticle was invisible.

I downloaded a couple of manuals (for the Temma 2 jnr & 2M models) and nowhere does it show a diagram of any switch for the illuminated reticle. It does describe an adjustment for illumination level, which I take to be the small set-screw next to the power indication light. Adjusting this screw does seem to adjust the brightness of the red light visible inside the mount.

Does this mean the reticle is permanently illuminated when the mount is powered on?

What may have happened is for the light source (LED?) to have moved from its usual position, so that it no longer illuminates the reticle. This will require opening up the mount to see what is going on.

Does anyone have any detailed schematics of the EM-200, or have any experience in opening one up?

Given the polar scope is a key feature of this mount, I'd really like to have this fixed before buying the mount!


Thanks for any help or suggestions you can offer,

John

The Mekon
09-08-2016, 08:25 AM
Nothing visible in the polar scope? - Check dec shaft orientation. Most are set up so polar scope hole aligns at 90 degrees. I have an EQ6 (EM200 clone) and the puck was set this way. I re-aligned things so that the scope hole is straight through at the zero position on the dec shaft.
As for the illumination, have never seen a mount yet where the SCP stars were visible with the light on. Wave a red light in front of the scope every now and then to see the pattern as you align.

Dennis
09-08-2016, 08:39 AM
Hi John

In my EM 200 Temma 2, the red LED that illuminates the Reticule is just crimped/soldered onto 2 floating wires and if those wires are moved, the LED fails to illuminate the Reticule.

I tweaked my LED position by carefully poking a small, rounded end wooden dowel down the hole at the front of the DEC housing and gently nudged the two wires, through trial and error until the FOV was illuminated evenly.

However, if the red LED does not work or the reticule is just not visible for some reason, you can always use the QHY PoleMaster (sold by Gama Electronics (http://www.gamaelectronics.com.au/polemaster.html)) to achieve excellent polar alignment.

Cheers

Dennis

johngwheeler
09-08-2016, 08:49 AM
Thanks for the suggestions. The Dec shaft was orientated to expose the hole through which the polar scope objective can be seen.

I have read that the reticle is quite bright even at its minimum setting, and that it was just about OK to find Polaris. I imagine it would struggle with Sigma Octanis. Your suggestion of waving a light to see the reticle is a good one as a temporary workaround.

Thanks,

John

johngwheeler
09-08-2016, 08:53 AM
Hi Dennis,

Thank you so much for the photos - really useful! I'm also surprised how crude the arrangement is - not what I would expect from Takahashi.

Does the PoleMaster fit the EM-200?

John.

Dennis
09-08-2016, 09:00 AM
Hi John

Yes – there is a mount specific mechanical adapter and then the PoleMaster CCD camera unit.

I used to be a dyed in the wool Tak Polar Alignment ‘Scope (PAS) zealot and since I acquired a PoleMaster, I have not looked back.:)

The PoleMaster is so easy to use and takes just as long as using the PAS if you factor in all the Month/Date calculations, eyeballing, kneeling down, etc. when using the TAK PAS.

Here is another photo showing the LED configuration.

Cheers

Dennis

johngwheeler
09-08-2016, 10:45 AM
Hi Dennis,

Another question for you. Is the position of the reticle on the polar scope tube fairly obvious? I imagine there is some kind of opening in the tube to allow the LED to shine on the reticle, so it would be handy to know where this is so that the LED can be more accurately positioned.

Thanks again,

John

beren
09-08-2016, 11:04 AM
One suggestion the owner may have turned the brightness dial to its lowest setting and may of broken it , there's a warning in the manual about it ......doh did it myself. The Tak pas is easy and accurate once you understand how it works and when you can readily identify sigma Octans . But like Dennis I use the Polemaster now most of the time , pity it came out just after I sent a Tak mount back to Tak HQ to get the polar scope updated (and switch fixed).

Dennis
09-08-2016, 11:05 AM
The reticule should be visible in daylight when you look through the eyepiece of the PAS with the exit hole open to daylight.

Or, if you are indoors and it is dark, just rotate the DEC axis so the PAS exit hole is open and if you shine any light across or down the hole, the reticule should be plainly visible.

From memory, I do not believe that the eyepiece of the PAS can be adjusted to the point where the reticule is completely OOF and “invisible”?

The red LED simply “floats in space” and I just eyeballed it down the DEC axis hole until it evenly illuminated the reticule.

Cheers

Dennis

johngwheeler
09-08-2016, 11:33 AM
Re the bold text: Is the reticle brightness controlled from the PAS eyepiece on your mount? On the Temma 2, the brightness is controlled by a small flush-fitted potentiometer next to the power light.

I guess it's just a matter of moving the LED around to see if things improve. As it stands, there isn't even a hint of illumination, so maybe the LED is not outputting at the correct level. It is clearly noticeable inside the mount housing, but not very bright - probably similar to the LEDs in illuminated reticle alignment eyepieces.

Thanks,

John

Dennis
09-08-2016, 12:06 PM
Hi John

No – the brightness is controlled via that fiddly, hard to get at, indented, slotted screw in the control box on the mount.

I was alluding to focusing the eyepiece in case it was capable of being adjusted so that the reticule was completely out of focus – I’m not sure if it can be focused though?:shrug:

Cheers

Dennis