Telescope Reviews: Sphinx tune-up and Version 2

I got a Sphinx SXW mount last April, which seemed to work perfectly from the start. I had only my Vixen ED80Sf at the time. When I got my 7" Mak, however, I could see that slow speed slewing in DEC was quite jerky. Still, go-tos and tracking were quite good. During the winter, however, the mount really started to slow down and I only used my little refractor on it. Moving it from north to the home position (pointing west) would take about a minute, and slewing from one object to another seemed quite slow.

I contacted Vixen support about these problems and was told that I had inadequate power and that I should use an AC adapter. I didn't buy this since the power had been adequate BEFORE, and I tried every one of the my 3 12v batteries with the same result.

I was considering sending it to Vixen a few weeks ago for these problems but decided instead to have Steve Forbes (Telesccopeman54) do one of his tune-ups. Steve loosened the DEC and RA axes so that balancing is much easier. He found that there was virtually no lubricant on the bearing under the saddle, and that it was starting to wear. He replaced the bearing, cleaned and re-lubricated all the necessary parts with a higher quality lubricant and adjusted the gears and worms. End result: a much quieter and faster Sphinx. It now gets to the home position in about 15 seconds.

However, Steve was not able to eliminate the DEC jitters and concluded that the motor was probably defective. He contacted Vixen and their answer was: download Version 2 of the firmware. I had been running Build 31. Last Wednesday, I had the Sphinx and Mak out for hours. The go-tos were perfect and after I got the balance right, tracking was perfect with Build 31 and I was very skeptical that different firmware was going to stop making the DEC motor jump around.

Last Friday, I headed up to Steve's place to see if he wanted to try making any additional adjustments to the DEC gears. But first, we decided to update my Starbook with Version 2. Steve had already downloaded the file to his computer. That process took all of about 2 minutes.

We connected the Starbook back to the Sphinx and discovered that the mount is even quieter now when it slews and slow speed slewing in DEC was noticeably smoother. Not perfectly smooth but smoother. So we decided to leave everything as it was and have me try it out for a night before making any decisions as to whether to replace the DEC motor.

So I finally got out last night to try it out. It was very calm, transparency was good and the seeing was supposed to be good. I set my tripod up so the feet were on the marks I made on the driveway that provide an adequate polar alignment so that go-tos are accurate. I tried to start my alignment process before it got dark, as I often do. Unfortunately, the go-tos were lousy all night and so was tracking. I'd repeatedly go back to the same object and sometimes it wouldn't be in the field of view of the eyepiece, although it usually was visible in the finder scope. If it was in the field of view, it wasn't centered. And this is after aligning several objects with a 9mm reticle eyepiece. and realigning on the same object after returning to it. I tried adjusting the counterweights up and down the shaft but nothing seemed to help with the tracking.

Another annoying thing: the appearance of the Starbook has changed with version 2. It's much harder for me to read. And navigating around it is much slower.

I'll give it one more night and pay closer attention to my polar alignment. If the go-tos and tracking are not noticeably better, I'll try to find a computer with Windows installed on it and download Build 35 instead to see if that helps with the go-tos and tracking. If not, I'll reinstall Build 31 and deal with the jerky slewing.

One thing I am happy about: with Steve's efforts, the mount is easier to balance, slews faster and quieter, and I know that the parts that should be lubricated are actually lubricated. Steve also adjusted the backlash of the gears so the mount responds much more quickly. I can tell you that if I decide to have the DEC motor replaced, I'll ask Steve to do it rather than sending it to Vixen.

THANK YOU STEVE.

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Amy