STT8300M Filter Wheel Failures

This problem has plagued my STT8300M since my original purchase of the camera new about 2 1/2 years ago. The problem is that fairly often (several times a night) the filter wheel will get stuck moving between filters. At least that is what the ASCOM driver is returning to the control program SGP (Sequence Generator Pro). I have never physically tried to check that the wheel was actually stuck in some mid-position. The image control program just gets a failure response from the ASCOM driver after a filter change request, and therefore halts its taking of images. If this happens when I am no longer monitoring the session, then I get no images for the rest of the night.

Here are the relevant details:
1) When the camera exhibits this filter stuck in moving state, I can fix it in 2 possible ways. First I go to the filter control panel where you can choose a specific filter and click the Set button. This usually causes it to successfully load the chosen filter. If that does not work, I have to disconnect the camera via the software, power it down, wait a few seconds, then power up and reconnect. This generally works (see following item on temperature dependence).

2) When first powering up the STT8300M and connecting to it under ASCOM, about 1 in 3 times it comes up in this stuck state. I have modified my SOP to always specifically check that the initial filter is successfully loaded when the camera is first connected. This has become more of a problem with recent effeorts to fully automate my observatory.

3) Somewhere between 50 and 200 filter wheel changes can be made before this failure appears.

4) There appears to be a significant temperature dependence on the frequency of failures. It fails at temperatures in the 60s F and 50s F and much worse with temperatures in the 20s and 10s. The colder temperatures usually require the power down/power up sequence to reset the filter.

5) I have tried both USB and Ethernet connections. Fails with both.

6) Last fall I had to return the camera to Bill for a complete replacement of the motherboard, which had totally failed. Unfortunately, out of warranty. I had great hopes that would completely solve this problem. Actually, if anything, it is worse. So I have a brand new motherboard and the problem is still there.

7) SGP has many users with STT8300M cameras. None have posted any filter problems on the SGP forum.

I have tried to deal with the failures by drastically changing my imaging sequences to try to minimize filter changes. I may take up to 10 images before changing to the next filter. It still fails a couple times a night. Bill is at a loss as to what might be causing this. Hopefully others may have some good ideas how to fix this. What components in the STT8300M could be causing this? What can we replace to try to fix it? Has anyone else seen anything like this?

 

This afternoon I ran CCDOps for an hour doing sequential filter changes. No failure. It changes filters about once every 3 seconds. I also ran SGP taking .5 second exposures which cycled through the filters with 3x3 binning for maximum speed. This takes an image every 11 seconds cycling through all the filters. Also for 1 hour with no failures. Ambient temperature 60 F. I will try some more tests tonight when it gets cooler.

Is there a way to program CCDOps so that it will take a programmed set of images using a specific sequence of filters? This would allow an exactly comparable test of SGP control vs CCDOps control.

I have only used the one computer for the past almost 2 years. It was a new Windows 10, 64 bit that has never shown any issues with any software. It is dedicated to running my obs so no unrelated software runs on it.

I don't think a power supply was included with my 8300. In any case, it has been powered by a fan cooled power supply that can be set between 11.5 and 13.7 volts, and is now set at 13 volts.

 

No need to try Maxim DL. I triggered a failure with CCDops. On two different nights this week I got these results:
Night #1: Ambient temp: 48F.
SGP: An hour of rapid image taking with filter change (11 seconds/filter change), no failures.
CCDops: An hour of rapid filter changes (3 seconds/filter change), no failures.

Night #2: Ambient temp: 34.7F. The following sequence of events occurred:
1) Powered up 8300M, connected to 8300M with SGP.
2) Filter status shows "FILTER MOVING", does not change for 5 minutes. From past experience it never recovers on its own.
3) Disconnect camera from SGP. Load CCDops and connect to 8300M.
4) Run Filter exerciser with Continuous checked. Image #1 is the CCDops screen (stuck trying to change filter):
5) No change for an hour.
6) Stop Filter exerciser.
7) Click Start again, Image #2 showing an error.

8) Stop Filter exerciser, close CCDops.
9) Power down 8300M, then power up 8300M
10) Load CCDops, connect camera, run Filter exerciser again.
11) No errors. Filter exerciser runs fine for an hour.

This is exactly one of the types of errors I have had with the 8300M.

 

Try slightly loosening the belt that moves the filter wheel. A couple of us had the same problem with our STXL filter wheels, and loosening the belt helped. If the belt is too tight, when it is cold it can keep the motor from moving. Search on the STXL forum for more info.

 

Thanks for the tip EricC. I will give it a try when I get back to my obs late April.