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Good Day; I just fired up my CEM 120 mount (after 36 cloudy nights!) and wanted to collect some HA on M1 (just after it passed the meridian) but upon three different attempts (after having to reset a new zero position each time due to a sudden unknown position) it would complete the DEC travel and start RA but then stop (for no obvious reason) and start whining loudly (it would either stop on it's own or I would stop it) and never make the target. After abandoning that target I decided to go to M82 (from another new zero position) and all is well (so far) and tracking/guiding is better than ever. It's minus 6 C but the operational spec for the mount says minus 10 as it's lower limit. Any ideas / suggestions? Thanks! |
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I dont know if its the same/related but eq6-r 's are notorious for this. The cause in that case is too low of voltage supplied to the mount, made worse by poor balance. if you run off a battery, it may not perform as well in cold temperatures and the higher amp draw of a slew would result in more voltage drop. It may also simply be low on charge. If you have a set of multimeters, or the mount controller/software may have a voltage readout option, you might be able to check this. In my case with an eq6r, battery would supply +12.4v, but after voltage drop the mount would recieve 11.6v or less with the standard power cable. I use a 13.8v DC booster. Just my 2c from experience. |
2.61
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One time my CEM120 did that with that kind of winning noise was when it hit an obstruction, so I assume you have checked for that or some sort of cable snag, although with through the mount wiring that should not happen. However you might check the big thick cable at the base of the mount that can snag on the Alt adjustment. Another time was a serious lack of balance after I removed a bit of equipment but failed to rebalance. The mount can also stop around the Meridian due to flip limits in either the driver or control software but that should not cause a noise. |
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| I have had the same problem and this was due to to lose or to tight gears on the RA. Have you tried to losen the RA gear tension? Just a very slight bit should fix the problem. There is a video on youtube and some documents on the Ioptron site how to do this. |
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| Ive had a few times on a few cem120's. Adjust the worm meshing a small amount. It needs to be losened slightly as it is binding. You need two allen keys both different sizes to each other. The worm lock must be on, allen key into hole you are looking at and undo a turn. THen other allen key up from underneath, this is the adjustment screw. Undo it 1/8th. Retighten top hole. Test it. On the hand controller slew at FULL speed. Listen carefully. Adjust until noises gone. As CEM worms are "sprung" loaded, this adjustment can easily be made. Rember the hole you look at from standing is to be loosened to allow adjustment. THe one underneath IS the adjuster. Its very simple and adjust in 1/8th turns ONLY. |
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Sorry just before you do that ... Mine made a hideous sound when binding. If yours is only "whining" or "whirring" then maybe yours is too loose which might suggest other issues ..c an you clarify if its just motor noise or hideous binding noise? If it was too loose, you would be able to move it by hand, so im assuming its more than "whining"? |
9.24
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Just to reiterate what others, while I'm not a cem120 owner, it sounds very much like its binding. Slew it through manually by hand, carefully, to reidentify it. It's not uncommon for the gear mesh to tighten up when it gets cold like that. Metal can expand and contract with temperature fluxes. Since factories are generally warm, the tolerances are set based on that temperature. On the off case it's a power issue, I would still address potential binding first, since you do risk damage if it continues to bind. |
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When this happened to me, I found a loose cable inside of the cable management input panel (on the RA axis). It has a green plug that was loose and would disconnect slightly causing this sunroof your seeing. It only happened at certain angles but would otherwise track fine. I ended up having to tape the connector so that it wouldn't come loose. I'll see if I can dig up a picture. Jason |
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Good Day; I have a Cem70 and the gears bind when it gets too cold. I have been told that you can take it apart and regrease with low temp grease, but I am not that handy. Here in MT I know there is a threshold below which the mount just won't work. On the contrary, I recently had my eq6r out in -25f and it slewed perfectly well. |
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| I also think it's a power issue. Make sure your power supply is outputting at least 12-13volts. |
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| Hi again and thanks for all of the replies - I ended up staying north to northwest after the whining incident and magaged to return to the zero position afterwards with no further issues. I think that it may be temperature related as mentioned in a few of the responses; I'll probably not bother to use this rig again until it's above freezing up here (we'll likely not have any clear skies up here for another few months anyway!). |
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I have had this issue quiet a lot. I first though it was a bad balanced as mentioned, but this was not the case. I then thought that it was poor mesh, but this also didn't quiet fix the issue. What it was was the USB 2.0 cable. This may sound odd, but i am running 5 meter cables and i went with a startech active extension cables. Never had an issue since. https://www.startech.com/en-au/cables/usb3sab5m https://www.mwave.com.au/product/startech-5m-usb-20-active-extension-cable-mf-ab68977 |
7.61
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I had the issue with my CEM 70 but only a couple times and not for a while now. Like you though, it occurred on very cold nights and my meshing is pretty tight so that seemed like the culprit. But, oddly, it happened only when I slewed to target. It never happened while slewing manually, even at the highest slew rate. In fact, a couple times I did several random slews to ‘warm up’ the mount without any problem but then encountered the binding when slewing to target after. Fortunately, after binding once or twice, the mount would work fine the rest of the night, and as the temp continued to drop. Anyhow, the issue occurred a few nights in a row 2 years ago but not since (and did nothing to correct it). That said, out loud, I’m sure tonight……. Cheers, Scott |
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I have CEM70 and got that worrying whine on one occasions - used in a lab to rotate a spectrometer, not outside for imaging. But had a similar issue. It might be binding, but unlikely for such large worm/gears on the 70 and 120, as they are normally shipped with some slack to the point where there are often recommendations to tighten the motor and belt. If you are plugged in or can see the power draw through software, or fully confident you are not low in voltage, then unlikely to be that. Long cables could be issue, maybe not. But, when the system needs to be rezeroed, you can get this problem. Never manually reset to zero whe you are in a failed slewed position different from the registered home position, as the software thinks it is pointing where it was and home position is way off - you end up running out of gear and its trying to turn when it cant. In that case, I unlock RA or DEC and manually move to see where the limits are and get back to roughly midway and ask the mount to find home automatically. You might already know this. Another issue can be the software resets the location data, and where you are pointing is not where you think, slews are way off and so is the home position. End result is you bang into the end of the axis turn, hear the whine and need to refind home position. Not sure if this is useful, for me it was a case of reset of the GPS coordinates, for others it can be a manual move to home that gives an offset to the actual registered home position, and it runs out of rotation when you try to slew. Zero damage done, stepper motors are astonishingly strong, but just eye ball the relevant RA or DEC belts just in case there is any thinned out regions that will give a periodic bump in guiding if so. |
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For me at least, the sound I heard when in the situation discussed has been identical to the sound when I know it's binding. I might have forgotten to remove the hex key (that lets you leave the RA unlocked when not in use) a couple times...... And yes, resetting the zero position after any slew interruption is essential....more confirmation of the binding sound when I didn't and the mount ran into itself when I sent it to zero...... Unfortunately, the find zero position function doesn't work on my mount. It slews past it and, again, runs into itself. So whenever there's an interruption, I have to move it to the zero position manually to reset it. Also have to manually set the mount to zero position at the start of each night because I unlock RA when not using it. Other issues...... Had a spate of "Cannot find any supported Ioptron devices" errors, but intermittently. I think a powered USB solved that, but never conclusively determined what was causing the error. Currently, my hand controller sometimes boots up fine, and sometimes doesn't get past the logo screen. Not a big issue since I use it very infrequently, and just out of convenience when I do. Really, I love my CEM70, but it sure is quirky...... Cheers, Scott |
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Ya, I gave up on the saddle power. Granted with two power inputs for both sides of the saddle give great options for power, but the USB was flaky and for my the iguider always disconnected. With a pegasus pb adv, every disconnection and mount connect failure disappeared immediately. Pity you're zeroing doesn't work. It should though, avoids any mistakes with manual zero position not being central to the full slew east and West. Did you Install the latest firmware? Upgrading is very simple now with the software tool, just on the off chance it might be useful. |
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I did try the latest firmware, but no luck. Ioptron offered to service it, but I don't want to give it up for a couple weeks.....that would only mean the longest run of clear skies and best seeing ever where I live!..... : ) Ioptron is only a couple hours drive away, though, so next time I'm going that way (like to Boston) I'll make an appointment to have them work on it that day. Cheers, Scott |
