Last updated: 30 April 2002
Subject: ETX 90EC Vertical Lock Problems..... Sent: Tuesday, April 30, 2002 16:37:34 From: IYoung@flooring.demon.co.uk (Ian Young) My ETX 90EC has just developed a problem - the vertical (or declination) knob won't tighten and the scope slips and points to the floor. I've undone the knob and inside there's a brass round type of nut set into the plastic. The knob screws into this. Unfortunately this nut has lost it's grip with the surrounding plastic and simply turns when it gets to almost tight. I've tried using strong glue to stick the brass bit back but it won't stick strongly enough to get a firm lock on the scope. I was wondering if anyone else had this problem with their Meade scope and how you managed to fix it. Regards, Ian Young.Mike here: The repair is easy, once you have the part (Right Tube Adapter) from Meade. In the states they will send it out free. Don't know about the UK. To see the repair, look at the bottom of this page: http://www.weasner.com/etx/90ec_comments.html
Subject: ETX-90EC Dec Worm End Play Sent: Sunday, April 28, 2002 20:47:16 From: email@example.com Wonderful site! I have a question regarding an ETX-90EC with Autostar. I hope I'm following the correct procedure (?) I bought one on the "first" ETX-90EC telescopes in Jan of 1999, and have not used it much at all -- (My primary telescope is an 8 inch LX200). I'm trying to tune it up a bit and get it in good operation for my son to use (in a different city). The Dec worm gear has end play as described in some of your archives and in Jordan Blessing's ETX/EC Tune Up article. However, I am unable to tighten it any further than it already is. There is still considerable end play -- I'd guess 20 mils or more. What is one "pushing against" when attempting to tighten the end nut? It appears the only thing holding the other end is the white plastic gear beyond the bearing. Is that tight enough and rugged enough for the nut to "push against?" In my case, I'm guessing the nut is already at the end of its threads (about 1/8 inch of "open thread" above the nut), and perhaps whatever the nut works against has slipped a bit or was never "far enough on."(??) Can a thin washer be put under the nut to "take up the slack?" As is (and as it was shipped), the end play results in about 1/4 inch or more up/down motion at the front end of the OTA -- too much I'm sure. Fortunately, the RA worm seems tight. By the way, the RA worm gets all the grease "cleanly rubbed off" in the center -- it's very shiny, indicating the gear is rubbing very hard in the worm. Regreasing it doesn't help -- it gets cleaned off and shiny in a few turms. Is this normal for worm gears, or are they engaging too tightly? Thanks for any advice? Art KotzMike here: First off, upgrade the Autostar to the current version from Meade's site (assuming you have the proper cable and OS). The version from 1999 is way old. You may have to put the Autostar into SAFE LOAD as described in the README if it the original version. As to the DEC play, are you seeing this when pushing against the tube by hand rather than when slewing using either handcontroller? Some play is normal; the Autostar attempts to compensate when you TRAIN the drives. And don't overtighten either axis lock; that can cause damage and may be the cause of the wearing you see.
Thanks so much for the quick reply. I'm trying to get it in shape for my son before I leave it with him at his home in the Wash DC area (I live in Minnesota and will be leaving in 2 days, so you can see why I really appreciate the quick replies). The OTA play is from moving by hand, but it is loose enough that it gives an "uncomfortable feeling" and the home dec position is pretty poorly defined. I realize the training should take care of the "backlash," but it's quite a bit of delay in dec movement. It's virtually a new scope since it's only been used 3 or 4 times in all this time -- so little or no wear -- yet. It's been somewhat of a disapointment due to the lack of rigidity, vibration, etc. (Got spoiled on the LX200 I guess, even though lots of people "knock" that as well.) Hope I can get it in reasonable shape since my son enjoys that sort of thing, but with a new infant child he has little time to fool around with "mickey mouse" equipment. The 5-planet alignment got us out the other night, so I decided to leave it with him rather than take it home, adjust it, and ship it back. Thank you again for the quick and knowlegeable replies and a GREAT site -- wish I'd discovered it sooner! Art KotzMike here: You mentioned that the HOME DEC position is pretty poorly defined. Not certain what you mean by that. In Alt/Az, the tube is horizontal. In Polar mode, it is parallel to the forks. Unless you have checked the DEC setting circle for accuracy don't use it. I just eyeball the HOME position. (If the DEC scale is off, see the FAQ for info on adjusting it.)
And an update:
The nut was indeed at the end of its thread, so I put a THIN brass washer (1/4 in. hole) below the nut -- and below the original thick steel washer and original "spring" washer, since the nut is a shoulder nut as you probably know, requiring a larger hole in the stock washers to go over the shoulder. It now works GREAT! I can adjust it for any amount of end play desireable now, Thanks again for the site and fun reading. Art KotzAnd this:
Thanks for the reply. By "Home dec position poorly defined" I meant due to the loose dec worm, the OTA tube could "flop" up and down 1/4 in. to 3/8 in. pretty much on its own (in Alt- Az OR Polar). That's all moot now since I added the washer and tightened the worm end clearance -- no more up/down flop. Thanks again for your kind attention and wonderful site. It is greatly appreciated. Art Kotz
Subject: Daytime usage problem? Sent: Sunday, April 28, 2002 12:25:33 From: firstname.lastname@example.org (Mark Gabrenas) I have just purchased a used ETX 90EC. The unit showed up well packed in the original Meade boxes, plus other boxes and packing around these. It is in cosmetically great shape, I can't see any scratches or damage on the scope or the lens/mirror. When I try to focus on objects more than about 1/2 mile away, I can't seem to get a good, sharp image. Anything closer than this reveals a great image. I took it out during the day to check (most celestial objects I can think of are more than 1/2 mile away!) and it seems to be consistent. I am using the standard 26mm eyepiece, which also seems to be in great shape. Any ideas what might be wrong? It is a great unit and otherwise performs much better than the ETX60 I upgraded from. And although you hear it all the time, great site. Without the advice of you and all your readers, I don't think I would have ever got the alignment of the Autostar down. Mark Gabrenas Apple Service Manager Apple Certified Technical Coordinator Elkco Corporation email@example.comMike here: Since it has been raining (according to your AstroMac posting) I assume you have not actually used it on the Moon, stars, or planets. I suspect you may be seeing the results of turbulence near the ground due to various heat sources and other junk in the air. Let me know when you have a chance to view the night sky through the ETX.
Actually, I did have one good night where I was able to look at the moon, Jupiter and Saturn (I had a long day, but got the scope that night and had to try it). I was able to see both Jupiter and Saturn easily, but found it very difficult to focus on them. The moon focused fairly well. I plan on trying again the next good night I get and I will let you know.
Subject: Re: ETX 90EC/Autostar problems Sent: Thursday, April 25, 2002 13:35:07 From: GeoffLinda@aol.com Hey, Mike, thanks so much for such a rapid reply. Here's us with all sorts of planets on show and no alt movement on my scope! Yup, I checked the batteries straight away, no change. I am a long-in-the-tooth radio maintenance engineer, used to fault finding on all sorts of modular equipment, from old valve radars to present day digital phone switches, which is why I got that sinking feeling when this problem came up. Since the Autostar gets it's power from the scope on switch-on, I figure that when I plugged it in, something in the Autostar blew on power-up, and that then blew something in the scope electronics. If I plug in the Autostar now, it is totally blank, with no response to any keys. If I plug in the regular controller, I get az movement but no response to the two alt keys. (though when I first power it on, I get the flashing LEDs, and if I press an alt key, although the scope doesn't move in the alt plane, it does complete the initialisation, and leave the #1 LED lit) This further confirms to me that the scope electronics are blown in some way. I've since discovered that the scope is still in warranty, having found a receipt for 1st July last year, so I'm about to e-mail Meade in the U.S. to see what can be done. My friendly UK Meade importers won't support Meades bought overseas, (without payment), which I thought was a bit mean, but that's international businesses for you! Thanks again for your comments, hope you have clear skies for the planets, we saw Mercury, Venus, Mars Saturn and Jupiter all lined up on Tuesday nite as we came out of the pub. Course, it could have been the Guinness! Cheers, Geoff Honeyands, somewhere slightly south of Oxford.Mike here: Yep, you may be right that something is fried. (By the way, Meade has no customer support email address.)
Talked to Meade US (we have cheapcheap phone access to US!), and I'm sending them the Autostar, which dont weigh too much, and I've asked them if they'd supply the two PCBs in the ETX for me to replace. Should be interesting, but then the Customer Support page on their website does say they will go the extra mile to keep the customer happy! I'll keep you posted, thanks for your interest, Geoff H.
Subject: re: ETX90EC Image Vibration Problem Sent: Wednesday, April 24, 2002 21:41:08 From: firstname.lastname@example.org (Richard Seymour) To: email@example.com > I think the problem is due to the motor drive as > looking through the eyepiece, the image constantly alternates between > sharply defined images and a vibration-induced blurr over a cyclic > period of a few seconds. This period conicides with the alternating > pulse/quiet/pulse sound from the altitude drive. The only time i have met that symptom (how many is a "few seconds"?) was with a 4504 telescope... every 13 seconds it would "click" during sidereal tracking... it turned out to be a -slightly- loose motor, being pushed out of gear engagement for only one tooth of a middle stage. > I have however no problem with the tracking or GOTO performance of the scope The "hopping tooth" -did- affect accuracy, but not by much... when the scope was moving quickly it didn't jump as much. It was mainly detected by hearing it, and -feeling- the motor box "snap" slightly as the motor moved -back- into position. Shimming the motor retainer would have fixed it. But the owner had a replacement motor box from Meade, and that -truly- fixed it. So -closely- investigate how well the motor (or other parts) are being held in place... you may also have a slight amount of dirt (or hair, or a burr) hiding somewhere. If you can -watch- the motors and gears move under power, you might see one gear which spins once in the same time span as the sound. YOu could also choose Terrestrial mode, and try moving the Dec/Alt motor at the slowest speed with the Autostar. Listen for the sound, and try to stop -when- it happens. Turn off power, and disassemble to see what position the mechanisms are in. This could be very tedious to track.... good luck --dickAnd:
From: firstname.lastname@example.org (acc) Hi guys Thanks for your wonderful support. I have partially disassembled the fork and observed the drive train while it is powered by Autostar. The vibration originates entirely from the motor! It is more of a pulsing from the motor as it is being driven by the Autostar in astro mode. Turning the motor (carefully!) by hand reveals no problem from the gears. Also, the pulsing is especially observable at the slower speeds but none at all at speed 9. I know pulsing is a standard way to get slow speed control from a motor but the problem is that this pulsing is sufficient to cause image blurring on my scope. (My mount is sturdy and shld not be the cause of the problem.) Wonder if Dick knows of any previous Autostar versions which pulses the motor more gently... :p I'm using ver 2.1ek. Maybe I will switch to a Ver 1.3 and see if the problem persists. Or could it be that my fork is 'too flexible'? :) And i found that I cannot mount the scope in Polar mode to get round the problem as this would mean missing out a good portion of the southern sky as I'm near the equator. Sigh. :) Thanks! AngMike here: I would suggest upgrading to the current version on Meade's site.
From: email@example.com (Richard Seymour) CC: firstname.lastname@example.org (Mike Weasner) > Wonder if Dick knows of any previous Autostar versions which pulses the > motor more gently... :p I'm using ver 2.1ek. Maybe I will switch to a > Ver 1.3 and see if the problem persists. Or could it be that my fork is > 'too flexible'? :) My fork is flexible, too... i'm trying to remember -back- to 21eK, and i don't remember extra vibrations. There have been quite a few updates since then. At least nine. The motor itself could be the problem... a dirty/worn commutator could make one portion of its rotation under-powered compared to the rest. Unplug the motor (or are they soldered? i forget) and check the resistance while you slowly manually turn it... you should see the interruptions as the brushes pass across the gap between segments, followed by the more-or-less equal values as the brushes rest firmly on the segments. If one portion is significantly higher or lower resistance than the others, that could be the problem. Be aware that a DC motor acts as a generator when manually turned, and don't blow out your ohmmeter by spinning too quickly. A few trips around with a voltmeter before using the ohmmeter would also show changes in load/output. Metal shavings or dirt caught inside the motor so that they interfere with rotation at one spot (but you would probably have felt that during manual turning). Even a slightly worn motor shaft bearing, allowing the rotor to shift a -tiny- bit at one point (and, other than a general "looseness", i don't think you could feel that. Version-wise: If feasible, i'd recommend moving -forward-, not back (although 1.3 was a fairly nice version)... the current version is 24Ea. You will also require the new Updater program to install it. (and the new Updater is -much,much- nicer than the old Updater) available at: http://www.meade.com/support/auto.html Perhpas a call/fax to Meade to get a new motor? (i don't know if they will supply a motor in isolation... perhaps contacting (via Mike's site?) anyone who has a dead circuit card in a DS- motor kit... you could extract the motor. (i do NOT know if they're the same) good luck --dick
Subject: ETX90EC Image Vibration Problem Sent: Tuesday, April 23, 2002 4:55:01 From: email@example.com (ACC) I have been using the 90EC and autostar for more than a year now and have been happy with it until recently when it started to give me problems. I notice that my altitude drive produce a very slight vibration that causes noticeable image blurring even at a low magnification of 50x. I know that the altitude drive is the culprit as stopping the motor temporarily will get the image back into sharp focus. I have opened up the fork but the gears seem to be OK. The vibrations seem to be caused by the pulses from the motor as it is driven by the autostar. The noise from the motor is easily audible even during tracking. I'm residing in Singapore so sending the scope back to MEADE doesn't seem like a good option. Does anyone know a solution to this frustrating problem? Now, to get a sharp image, I have to 'trick' the scope by doing a synchronisation so that the motor is stopped. Not a very nice way of observing that's for sure :-) Ang p/s: thanks Weasner for your site which is a wonderful resource for all ETX owners.Mike here: You can try moving the scope up and down manually (not using the controller). Do this with the axis lock UNLOCKED. If you don't feel any "grabbing" then there is probably nothing catching the telescope as it moves. Next step, do a RESET, RECALIBRATE, and reTRAIN on the Autostar. That may improve things. If you still have the problem, let me know. You could also try mounting in Polar mode (which removes the altitude drive from the tracking process).
I have verified that nothing is catching the scope as it moves. Doing a complete reset-calibarate-retrain has not helped either. The 'vibration' can be felt as a very slight pulsing of the OTA if I put my hand against it. I think the problem is due to the motor drive as looking through the eyepiece, the image constantly alternates between sharply defined images and a vibration-induced blurr over a cyclic period of a few seconds. This period conicides with the alternating pulse/quiet/pulse sound from the altitude drive. (I have however no problem with the tracking or GOTO performance of the scope). Yup, mounting in polar mode is a good get-around. Thanks for the suggestion. But I would have to beef-up my scope mount as being juz 1 degree north of the equator makes for a very unstable 90EC in polar mode :-) AngMike here: OK, lets try a couple more things. Move the telescope around both the horizontal and vertical axis several times, back and forth (hard stop to hard stop). That may help distribute the grease and provide reduced vibration. Also, you didn't mention the type of mounting you are using. Could you have over or undertightened the bolts holding it to the tripod? Did you change the mounting recently?
Subject: ETX 90EC/Autostar problems Sent: Sunday, April 21, 2002 10:04:01 From: GeoffLinda@aol.com Hey, guys, a question from sunny England, tho' I have a nasty feeling I already know the answer. I bought a 90EC and Autostar last year in March, when I was over staying with friends in Pensacola. The combination has worked fine since then, but for about the last 2 months I have been just using the supplied electronic controller, not the Autostar. So, last night, I figured it was time to hook up the Autostar and use the scope in anger. I switch the ETX on, with Autostar connected, and get no display, and no reaction to any button presses. The backlight to the display is on, but that's it. Bigggest problem is that when I remove Autostar and refit the Electronic Controller, I have no responses to up/down commands. I've tried unplugs and replugs, all with power off, but still Autostar remains blank, and still I have no up/down reaction on the EC. The EC reacts normally when you switch on, but the won't up/down. In addition, pressing either of the Az buttons gives about a 4 second slew (but only the once!). So my ETX is poorly. I'm pretty sure some of the electronics have blown, but just in case you guys have seen something like this before, I figured I'd ask. Any advice appreciated! Cheers, Geoff HoneyandsMike here: Well, the obvious question: have you installed fresh batteries or tried a proper AC adapter?
Subject: ETX/RA problem Sent: Wednesday, April 17, 2002 6:23:02 From: firstname.lastname@example.org (The Design Fort DTP) I love your website! Thank you for a great page like this. I have a problem with my 90 ETX/RA. The drive doesn't work anymore. I took it apart and found out, that the motor itself is still running, but the "Gearbox" with the little plastic gears has looked up. All my attempts to free them failed. It seems that I can't open up the gearbox since it is riveted together. I think I have to replace the part. Do you know where I could get this part, or is it part of a bigger replacement? Maybe you have one? Any help would be appreciated. Thanks for your time. Greetings Herbert Annapolis Royal, Nova Scotia, CanadaAnd this:
From: email@example.com (Clay Sherrod) Unfortunately the motor and gearbox assembly is one in the same and you much replace the entire unit. Although there are many ETX RA scopes out there, I very rarely see any for spare parts and this item is NOT something that typically gives any problem at all....the best solution is to contact Meade and see if they can arrange to send you the entire assembly since you are in Canada and shipping the scope may not be practical....otherwise they likely will ask you to send it on in! Of all the spare parts I keep on hand from salvaged scopes, this is one I have not seen lately! Sorry! Clay Sherrod
Subject: etx-90 question Sent: Tuesday, April 16, 2002 14:03:52 From: firstname.lastname@example.org (Grellas) I just purchased an etx-90ec. I took it out the first night and saw a few planets. Unfortunately - they were really small and hard to see in the 26mm. Do I need to purchase other eyepieces to be able to see things well with this scope or are there objects I can view comfortably with the 26mm? Maybe I should just buy your book. :-) Thanks. JPMike here: There are many objects that will appear nice in the 26mm. But increasing the magnification will enlarge objects like planets and the Moon and allow you to (perhaps) see more details. Adding the #126 2X Barlow Lens is a good starting point or some other short focal eyepiece. Keep in mind the maximum magnification formula (see the FAQ page if you are unsure). See the Buyer/New User Tips page and the Accessory Reviews - Eyepieces page for more on eyepieces.
Subject: Conversion of ETX Sent: Thursday, April 11, 2002 12:39:30 From: Stan.Hostetter@umusic.com (Hostetter, Stan) Mr. Weasner, I just received a copy of your book Using the Meade ETX and would like to know something. It never fails with me, and I'm sure others have had this happen too, but it couldn't have been much over 6 months when Meade came out with the new ETX-90EC. Of course I had just purchased the ETX-90RA. What I would like to know is can the 90RA be converted to the 90EX by the Meade Corporation? I look forward to your reading your book and if you could help out with my question it would be appreciated. Thank You, Mr. Stan Hostetter Fishers, In. Stanboater@aol.com or Stan.Hostetter@umusic.comMike here: See the FAQ page for info on the non-existent upgrade from the -90RA model.
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