I have been having problems lately with repeatable filter positioning. Let me clarify, usually this comes up when I'm taking a large number of different PA/Filter screen flats. I use ACP Expert so I may end up taking many different objects during the night, usually 4-5. I use the FlatMan XL flat panel which is a life saver for making my flats. ACP has a script that reads the current defaulflat.txt file and turns on the flat panel, sets the brightness as I have defined for each filter, and starts taking samples adjusting the exposure until it falls within the requested ADU count specified. This works great and saves a ton of time. The issue lately is the filter wheel (FW8) actually positioning the correct filter properly in the wheel. It will usually run fine for a while and then start having filters only partially centered. I sometimes get the "owl" look as the filter is split between two slots. Early on when I first got this new camera/filter wheel (STL-11002M/CF8) it worked great. Then after a few years the fw8 started to act up. A call to Bill Lynch was helpful in that Bill told me that the center screw that holds the carousel to the unit had to be "just right", like Goldilocks "not too tight, not too loose". This was concerning as there is no gauge for that perfect tension. There are other things such as the motor spring but that is positioned correctly, at least as best as I can tell. When it starts to act up I adjust the center screw and it usually works for a while. Too loose and it seems it gets looser with time and stops working altogether. This is not only very frustrating but time consuming and can result in a loss of data. And every time you open the filter wheel to make an adjustment you need to test it by running through multiple filter positions which means the unit is open longer increasing your chances of additional dust on the filters. I suspect I really need to send this camera to Bill Lynch but if anyone has had these issues and found a cure I'd really appreciate knowing what it is. Thanks, Steve
Steve: I have run into similar problems with the same camera but withe 5 position wheel. It may be that the spring which tensions the drive motor against the wheel needs to be stretched a bit to increase the tension. It is pretty easy for the spring to fall out when removing the FW, so make sure it hasn't fallen out. Also make sure the large "O ring" around the wheel is properly positioned and has not slipped out of its groove. I am sure you have probably covered these issues but in addition to getting the center screw there isn't much else mechanical that can go wrong. Good luck getting it working.
Thanks Gregg, I had checked the spring and "O ring" and all seemed fine. It's probably better I send the camera in. Early on the camera lost its "ID" for both the main and guider chip. Matt and I worked on it over the phone and we did get the main chip back to the proper id while the guider thought it was a 237 chip. That was also resolved after several attempts. Seeing how the firmware isn't upgradable on this camera without sending in and that Bill suggested there was a firmware update that may apply to this FW8 (depending on when it was made) it is probably best just to ship it to him and have it looked over completely. I just find it very expensive to ship and insure across the country. Thanks Again, Steve
I have run into the same problem with my FW8G filter wheel. I used purple Locktite thread lock on the center screw. You only need to tighten it enough to keep the wheel level (no up or down movement when pushed with your finger) but not so tight to cause undue friction while turning. Case closed..
