Padraic M Posted March 1, 2021 Share Posted March 1, 2021 Hi all, creating a new topic for this so I don't hijack either the Anyone Imaging Tonight thread or GazAstro's other HEQ5 topic. Background: HEQ5 Pro, astrobaby tuned and Rowan belt-modded, was giving me guiding of around 1.5". For reasons I now regret (!) I decided to go ahead and to replace the stock bearings on the RA axis with top-quality SKG bearings. The process was fairly straightforward, using Astrobaby's instructions again, and better quality SuperLube grease. The first results were disastrous - on the first night out I was plagued with equipment disconnections and general belligerence, including camera fails, mount refusals, but mostly telescope disconnections in NINA - lucky to get a connection to last for 30 seconds. Also, NINA doesn't like when things go wrong, so it hung, crashed, locked profiles, reset to factory settings, and eventually I reinstalled it from the last stable version. So, completely unusable, and very hard to make any modifications in the cold and dark. I re-stripped the following day, checked everything, applied more grease, and re-tuned the worm backlash to be slightly looser. There's a noticeable amount of movement in the axis now, but definitely no binding. I also loosened the RA worm end float slightly. Because so many different things went wrong, with no logical connection between them, I worked on the theory that tight bearings were causing the mount to draw too much current, and supply voltage was being pulled down below 12V. That would definitely cause random failures and drop-outs, especially with the mount. I'm not convinced now that that is the case; the power supply is the Nevada Radio 30A. I'm using the front 10A cigarette socket, and am drawing less than 4A at peak (both axes slewing; camera cooler and two dew heaters on). With the hand controller connected to the mount, supply voltage varies from 12.8V at no load, to 12.5V at full load. Needless to say, everything works absolutely perfectly under test inside in the warmth! Second night out was better, but still not usable for imaging. I connected everything gradually and monitored power usage at each stage. Using the hand controller at first, the mount slews happily in all four directions, with no stalling and no unusual noises. Powered down, switched out the HC for EQMOD PC connection and rebooted. All equipment behaving better, and NINA connection holding stronger, but still had a disconnect. I held off on connecting PHD2 as I had a feeling that the problems were worse when guiding. I remembered that while all of the other problems were happening, the PC would freeze up from time to time for about 6 seconds, then continue. Un-guided 60s subs were star-trailed. As soon as I connected PHD2 and started guiding, the NINA "telescope connection lost" error started again. Not as regularly, but regularly enough that I couldn't leave the PC unattended. Interestingly, neither ASCOM nor PHD2 lost their connections, just NINA. I focused in on PHD2. Cleared calibration data and recalibrated. Tried a test sequence on Bode's which is nice and high, and free from the worst of the light pollution in my garden. Scope W facing E was ok - generally got ~2.4" guiding, with two disconnects over a 10x60s sequence. Better than nothing, but worse than it was. Restarted the sequence and obviously Bode's had crossed the meridian so slewed to Scope E facing W. Now it failed entirely to track. Regular 'telescope connection lost' errors in NINA, and PHD2 'unable to make sufficient corrections in RA'. Screenshot below - notice the funky guide graph. Now I think the key phrase is 'check for problems with the mount mechanics'. Current theory is that the mount RA is either binding in the cold temperatures, or has too much RA backlash to make the necessary adjustments. PHD2 is trying to compensate, and is sending multi-second pulses to the mount. Can the PC freeze while waiting for the mount to respond? I suspect the telescope connection to NINA is timing out because the PC has frozen. So, how can I tell if the worm is too tight or too loose? What's the interaction between worm tightness and worm end-float? My best guess at the moment is to loosen both the worm and the end-float on the basis that binding is more likely to cause these problems than backlash is. If I can get PHD2 to behave a little better, then I can measure backlash and attempt to adjust for it. Finally, has anyone had the same issue with the PC freezing for a few seconds at a time? It's a new laptop, i7 core, lots of RAM and SSD drive. New USB 3.0 StarTech hub. Quote Link to comment Share on other sites More sharing options...
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