Hi, last couple nights Maxim has died on a filter wheel error. Thought it was software 'till I went upstairs and checked it it made some stuttering sounds when booted. I thought the belt might be loose so I opened it up and it looked good. On the bench when booted it may work for a while, then when given filter wheel change, does not do it. And/or may stutter. I guess I better call Bill. I worry about a loose connection but everything looks good though could always be a hairline crack. Is the motor something I can replace myself, to get it done faster and avoid all the shipping costs? I also should replace the fans. This must be 5 years old now... was one of the first STT-8300Ms in production. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Read this thread on tensioning the belt and motors etc... sounds like a black science. http://forum.diffractionlimited.com/threads/fw8g-stxl-fails-cfw-motor-timeout.2916/#post-16771 I ran it again and looked inside when it stuttered and the wheel was between notches for filters... hard to tell if the tension is wrong (seems OK to me... not too tight) and it does move occasionally, so perhaps more likely weakening motor? This of course occurs when it is cold here, but it is warm while I am testing it.
It's rare for one of these stepper motors to fail. If it does, it would be a bad bearing. One suggestion is to loosen the tension and pull the drive belt off. See if all the parts - wheel, idler, motor turn smoothly by hand. Being a stepper the motor will "cog", but it should move fairly easily by hand. If any of these are excessively stiff they may need to be repaired. I don't really recommend DIY repairs though, the parts stack up on the bearings is a bit complicated and you could easily make a mess of it.
Thanks Doug... how do you loosen the tension? Nut on top? I can move it all with my fingers.. i.e. rotate the gears...
On STT I believe it’s the idler. If it rotates smoothly with the belt attached then it may be the motor or the electronics. But also check that you’re getting good power.
Fingers crossed. Ran CCD Ops and seemed to run better. Then adjusted nut on belt to loosen and it worked better but still stuttered. Tightened and went back and forth for 1/2h. Ran 5 full cycles of filter changes with Maxim with no problems, so put it back on and will say some prayers. Appreciate getting back to me on Sunday ....
PS The sucker is still guiding at 1030PM... beddy bye. Lousy seeing makes it hard to evaluate quality of guiding.... but can't blame Maxim for that.... Ran all night correctly. Fingers crossed. But would like to understand how that little nut adjusts the tension. I think that must be what it does?
Hi Doug, I chatted with Bill yesterday and although there is no procedure, let me tell you what we worked out and we think is the tentative fix. The bolt identified on that previous thread essentially is on a slider that can adjust the tension... move it out from the filter wheel and tighter and move it in and looser. The guide is how it feels... not too tight- not too loose. The problem I had was that I did not realize there was a screw on the bottom that had to be held when you tightened the nut. So my "fix" did not hold. I fixed it again yesterday and ran 100 filter changes at Bill's suggestion... fingers crossed that it will hold in the future. I think what happened is that the cold winter weather contracted everything and the belt was too tight. When I tried to loosen it, it worked for a time but got too loose since the nut was not fully tightened down. Anyway, I put this in here in case someone else runs into the issue. As I said, I hope it lasts. If it does, this should be the last word here. JY PS Now I have to re calibrate the guiding and that is not working out so well. if it fails tonight, will be asking more questions. I had a problem in the past where the X (RA for me) axis wanders off. I think it had to do with some sort of error relating to what side of the meridian you did the calibration on and some setting having to do with meridian flips.
Sounds good on the filter wheel; I will mark this as resolved. If you want to talk guiding please open a new thread. In the meantime please read: http://www.diffractionlimited.com/help/maximdl/Autoguider_Troubleshooting.htm and http://www.diffractionlimited.com/help/maximdl/Backlash_and_Stiction.htm
