STL-11000 guiding issue

Having some issues with the internal guide chip on my STL-11000. Last night I had just started an imaging session when the guiding stopped working without warning. I was three subs into my session, they were 10 minute subs and they looked great. Then on the 4th one, all of a sudden the guider started reporting a whole bunch of error and moved the guide star halfway across the frame. I wasn't even near the scope when this happened, I didn't even discover it until the 6th sub, I didn't touch or change anything. I aborted the sequence and tried to re-calibrate the autoguider, which didn't work. Kept getting different errors, "Invalid motion in X-axis/Y-axis", "Guide star too close to edge after movement" (it wasn't), "Not enough movement in X-axis/Y-axis." I played around with the various autoguider setting to no avail. I tried to guide with the previous calibration and watched as the autoguider moved the guide star out of the frame within 10 seconds as it reported huge errors. My polar alignment was pretty spot on, as the object I was imaging remained centered in the frame as I was fiddling with the autoguider over the course of two hours. There were no clouds in the sky whatsoever and I was hooked up to a power outlet, so no portable battery issues. This is the second time this has happened, and I have no idea what could be causing this or what to do. If anyone has experienced this before or has any ideas on what the problem is I would appreciate the help!

-Joe

 

Hi,
Have you checked that the STL-11K USB cable is firmly plugged in? You may have momentarily lost communications with the STL (RGH ?).

I find the USB cable "plug" can become a fairly loose fit, begin to rattle a bit, after years of wear from dragging its cable harness. Mine wasn't tight, so I wrapped my USB plug (tip) with one small approx. 1/2" strip of thin aluminum tape (not the one with the insulation foam for heating ducts, but the one used for stove vent or dryer ducts), which then made it an extremely tight fit into the camera USB socket, good for years of cable "squirm".

Joe Z.

 

Hey Joe,

Thanks for the response. I'm not sure that the USB cable was the issue, as I had constant connection with the main imaging chip throughout this process, and the guiding chip was actively taking test frames as I was troubleshooting without issue. I'll certainly give it a try, but it may be more likely that the guiding cable has gone bad, although that seems like a stretch as well because it has worked fine recently. I'm a little concerned that this is a more serious issue.

-Joe

 

Hey Colin,

I'm using CCDSoft to control both camera chips. I don't have MaxIm and I think CCDOps is essentially the same thing as CCDSoft? I'm running a Windows 7 laptop, using CartesDuCiel/EQMOD for mount control and CCDSoft for camera control, that is the only software open during acquisition. The USB cables are all standard, although the USB from the CCD to the computer is a little long. The only note worthy item with the cabling is I've noticed the 9-pin guiding cable that connects to the camera body only has 5 pins in it, it is missing 4 pins. Looking at the user manual it only uses the 5 pins that are on the cable, so I figured this was intended and a non-issue. I know this setup works as my last night out imaging I had a successful 5-hour session with no issues, although the time before that I had similar problems. Not sure what other info I should provide, but if you need anything else please let me know and I will answer as best as I can.

-Joe

 

Joe,

Just another thought. You say that this was using the "INTERNAL" guider - not an external RGH.

I wonder if the problem might be the "guider cable and its camera port adapter". If it is loose at either end, or the adapter holding it in the camera, then any drop outs in the relay commands to bump the mount would "randomly" lose target tracking. Those aren't actual messages to the mount, but X-Y relay contact closures, so I wouldn't expect any feedback errors from CCDOPS/CCDSOFT regarding the guide channel about "lost frames"- just the obvious random motions or stops in tracking which is reporting the resulting odd target positions. Being just contact closures, the software can't monitor mount commands for syntax as it might if actual Meade type text commands were sent to a mount's serial port. Relay control is very basic.
Might be worthwhile checking all the linkages from the camera guide port right to the mount. Something may be rattling.

You could eliminate the internal guide chip as a suspect, by simply setting it to take a huge pile of darks, perhaps during a full day, and count how many subs got saved. Or, if you like, let it take subs of a poster on a wall for that long,. Then later check the quality and consistency of real poster images. I wouldn't be surprised if they all turned out error free, in terms of reported messages and image consistency/quality. If they all got saved and the expected tally matches, based on their interval and duration, then your internal guide chip is probably fine, leaving the actual mount bumping as a suspect - and which is an inexpensive DIY easy fix with a replacement cable or new adapter dongle. Otherwise, if the guide cable looks solid, might want to replace the RJ-11 modular connectors on the guide cable ends - its pins may have oxidized or corroded over time, so any mount motion may cause intermittent mount bump drops.

Anyway, I think it is worth checking to eliminate a possibly simpler cause.

Joe Z.