Last updated: 26 June 2002
Subject: New ETX90RA Sent: Monday, June 24, 2002 14:42:56 From: firstname.lastname@example.org (Arik Shafir) I wanted to give everyone who reads the site a heads-up on a good deal. I just got my ETX 90RA from vanns.com for $186.89. If you look on the site now, it says $249, but call them up and tell them you saw the promotion last week and want the old price (it worked for me). Unfortunately, the scope arrived with a broken tripod leg and a piece of debris in the viewfinder. When I called up Meade they were cool about just replacing both parts, no questions asked. Luckily I live about 15 minutes from Meade headquarters in Irvine. Plus, who wants that 8x21mm viewfinder anyway? Thanks for the informative site. Arik
Subject: Something wrong?? Sent: Tuesday, June 18, 2002 10:04:32 From: Flepisko@dwave.net (Frank Lepisko) Found your site while in the throes of my first scope purchase, in fact , reviews and information here led me to choose My ETX -90RA. Great site ; Unfortunately I can't say I'm equally as enthusiastic with the RA. In fact I am severly dissapointed with it. I was prepared by a couple of months of research and binocular viewing to not expect hubble-like images. However;with the supplied 9mm eyepiece Jupiter appears as a blurred/fuzzy disk ( like a pea held at arms length) and colored banding is barely discernable. I try to be gentle and especially critical with the focus but to no avail. I tried some double stars the other night but the stars won't focus to a point either. Daytime terrestrial use in bright sunlight proves focus is only just okay... but contrast is not what I would call razor sharp and snappy. Now with your 1500 mile long screw driver... Could I be experiencing dew formation or "poor viewing"? Should I send it to meade for collimation? Should I give up and go back to my trusty bino's? Also I notice the ETX On the sites' home page has an external 90 degree prism added, is this the "hot set up"? Thanks for any help or encouragement you can offer on this issue. I realize you can't look through my scope (also I haven't seen any local star-parties to compare other views). Help, regards, frankMike here: Right now Jupiter is very low in the atmosphere and so views of it will suffer from distortion by the Earth's atmosphere. However, you should be able to bring stars to essentially pinpoints when they are near the zenith. You didn't say whether this was a new or used ETX-90RA but see the Telescope Tech Tips page for information on collimation testing using a star or other objects. Try that to see if it needs collimation. You might also want to see the "Telescope Performance" section on the Observational Guides/References page (there is also a star test item there).
Subject: ETX-90 Depth of Field Sent: Sunday, June 16, 2002 19:02:56 From: email@example.com I have an ETX-90RA (Well two of them actually). I do not do much terrestial viewing but recently did and noticed that both scopes are sensitive to depth of field, ie objects in the background are not as sharply focused as object in the foreground. I can focus on the background and the foreground loses focus. I have tried 39X, 49X, 100X, and 195X powers and can notice it at all powers. At 195X both scopes are razor sharp, I continue to be amazed at the optics. It is not really an issue for me, but rather I am wondering if this is a common aspect of the Maksutov Design. Thank You RandyMike here: Well, normally depth of field isn't an issue nor a design consideration with astronomical telescopes due to the distance of objects observed. But, just like with cameras, you could stop down the aperture, but only to a point due to the central obstruction.
Subject: My ETX Sent: Wednesday, June 12, 2002 15:53:52 From: firstname.lastname@example.org Hi all, I'm owner of a Meade ETX. My problem? in the front lens, bonded to the mirror, there's a black sleeve. On my ETX this bonding is going bad so the sleeve as partially moved downward form the original position. Doing that the glue has contaminated the lens. I'm really angry for that. Is there anybody that can give a suggestion how to rebond the sleeve? At moment I cleaned up the lens form the glue ... let's say that the ETX works all the same .... BUT!!! Regards to all Mario Agus - Italy p.s. great siteMike here: Glad you like the Site. Sorry to hear about the baffle problem. The best choice is to return it to Meade but if you want to try to fix it yourself see the three articles on baffle repair on the Telescope Tech Tips page.
I didnt take enough time to look the site entirly amd the answer was there. My best regards Mario - OLbia, Italy
Subject: gears Sent: Wednesday, June 12, 2002 11:18:55 From: email@example.com (Clay Smith) like your site, just starting out. have a etx90ec. i used the gear drive to point it directly overhead to see jupiter, ( a few months ago) and heard a grinding noise as it pointed straight up. i would think they would have stops in them to keep them from doing something like this. it wouldn't move much after that, so i took it apart and there is two small plastic gears that look alike just different positions and one of them is missing some teeth. is there anywhere i can get replacements without sending in to meade. they want a ridiculous amount and they won't sell the gears to me directly. (it's out of warranty, bought it second hand) somebody should come up with some hardier gear material or replacements i just pointed it up. any ideas? have pics of the gears if the parts are available. thanks in advance.And from our hardware expert:
From: firstname.lastname@example.org (Clay Sherrod) It does sound as if the scope moved past the hard stop and torqued out until the small gear stripped; it should not have gone over that limit, but sometimes when moving manually, the scope will keep on going as far as you try to force it. I assume that this was NOT a "Go To", but you had manually slewed to that position.(?) Meade's policy is just as you state and you nor I , nor any dealer can buy these parts; the only options you have at this point will be to try to find a "salvage mount" to retrieve the gears from or send to Meade. At last report, Meade's charge to fix this - and everything else that you report when you send it in at one time....is only $75; that would be a pretty good investment if other work or replacements needed to be made, and you can request an optical collimation at the same time for no additional charge. Best of luck! Clay SherrodAnd a response:
yes, i manually slewed it. i appreciate your reply. thanks. i guess i will have to bite the bullet. sounds like a good side business for someone, make generic replacement parts for meade scopes, high quality of courese! thanks again.
Subject: ETX 90 Sent: Tuesday, June 11, 2002 23:12:57 From: Uey2348@aol.com I have a ETX 90 Telescope and while I can use it to it's modest uses, I have trouble getting images like the examples I see on your website. Do you use different lenses and eye pieces? I have a 26mm, 18mm, and 9mm lenses as well as the Barlow 2x lense. I have a blue and red filter for the scope as well. Any information you can provide would be much appreciated. Thank you and have a good night. Gene Kenney, PN2/USNMike here: You have an excellent set of eyepieces. Keep in mind that many of the images you see on the ETX site and elsewhere have been digitally enhanced and may not accurately reflect what the eye sees. Can you be more specific about your problems?
When I look at Jupiter or Saturn I only see a small image, even when I use the 2x lense. Also, I can only get a outline of the Crab Nebula (by Orion). I have a blue and yellow lense but can't seem to make those work correctly.Mike here: You should be able to see cloud bands on Jupiter (even without a filter) and the Rings of Saturn. However, Saturn is essentially gone from viewing now and Jupiter is low in the west at sunset, meaning the views will be distorted by the atmosphere. Many deep sky objects are faint fluzzy blobs in small telescopes. Photos can store up light over long periods of time; that accounts for the difference you see in photos vs your eye.
Subject: Delay in Dec response Sent: Sunday, June 9, 2002 13:37:42 From: email@example.com (Joseph Rodricks) I recently completly disassembled my ETX 90. I cleaned it throughly and de-greased alot of surfaces that shouldn't be greased. I took apart the gear box and motor drived units. I have two qaustions. One is simple: what is the right kidna of grease to use and where do I get it? However the second question is a little more involved. I've noticed a considerable delay in the dec drive's response time. This is not the typical gear lag noticed when changing drive directions. It seems there is any where from 1/2 to 1 1/2 seconds of delay from when I push the AustoStar's button and when the motor actually powers up. This happens reqaurdless of slew speed and only on the Dec drive. I have taken the fork arm cover off with and without the weight of the OTA. If I have described the problem correctly then you won't suggest the Alt/Az. % adjust. (Because, as I know you are aware, that solves a different, bu simular problem.) By the way, I have tried it, just for kicks, and it doean't work. I'm not sure if it's a motor problem, software, or what. My gear box is nice and tight and there is virtually no compensation needed for the gears to catch up to themselves. Please send any thoughts or suggestions. Also, I am still looking for the right grease. Thank you Joe RodricksAnd:
From: firstname.lastname@example.org (Clay Sherrod) If there was "no compensation needed" for backlash then there would not be any delay; you need to remove the fork arm cover and press a speed, say "5" and watch each and every gear. One of the small transfer gears must be slipping until it reaches a high point on the small axle; at that point it likely is engaging....once moving it will stay moving until stopped. If you press a slew key (which direction, by the way...up or down or both?") watch each gear.....if all move instantly, then there can be very little delay. So, something must be hesitating from bottom to top. ALSO, on of the most common problems for folks who work on their own scopes is overtightening EVERYTHING....the gear system MUST have some slack or you will burn up the motor and strip the gears. I have seen 2-3 second or longer delays from: 1) worm gear tightened down way too tight and not turning freely as it should....should spin like a top with the flip of your finger without the other gears attached at each end; 2) clutch assembly too tight; 3) worm pressed entirely too tightly against the drive gear; this binding will wear your motor out. Based on the fact that it worked fine before you did your exploratory, and the amount of delay, would say that you clearly have overtightened one part of this gear train. Check that first. Clay SherrodAnd:
Previous to my exploration, the OTA was slipping. Then I remove the fork arm covering and watch the gear train work (without any weight of OTA- so clutches are not the problem) I am able to very specifically localize the problem. The gear train is properly aligned and greased, once it starts spinning there is no delay and everything is tight. It's tight in a good manner, as gears should be, but not overtight. The problem, I believe, may be the actual motor itself. On the end of drive shaft (for lack of a better term) that actually comes out of the motor is a gear that (I assume) is permenantly attached to motor. It is this that is slow to start. This is true even when there is no gear train! In the picture below I have painted to the gear which is slow to react. Remember that once this starts to spin (regaurdless of the autostart speed setting) the rest of the drive train reacts instantly. I am so close to perfection I can taste it! Maybe my Autostar? I've never used another Autostar, though from day 1 it always seemed that I had to bear down on the buttons a little too much to get things to respond. I wonder if it is, perhaps, that Autostar itself that it giving the command late. Clay, you once had my autostar, I doubt you remember but I would think that you would have mentioned to me if it felt there was something wrong with mine. So I guess I can rule that out. Thank you. JoeAnd this:
From: email@example.com (Clay Sherrod) Joe - I think I know what the problem is....you are hearing motor activity far ahead of actual kinetic response. What I believe has happened is that the windings in the small motor are likely going bad and NOT producing enough magnetic torque when first activated to "get the ball rolling." It is requiring the motor to spin and build up enough kinetic energy to convert to the necessary flux to spin the shaft appropriately. In some situations, you could merely add more spunk ("volts") to push the motor past its present limits but that is not desirable here, PROVIDED that you are not attempting to run with the AA batteries....you are using a reliable power source, right? Unfortunately you have done yeoman's duty in perfecting this drive system, but you are to a point that - unless you can find a substitute motor (and Meade will NOT sell you one!), you may have to accept those momentary delays. Best of luck.... Dr. ClayAnd:
Thanks. What if.. I get a simular motor and put the same gear on the end of it that is on it now? With the optical sensors still work right and the Autostar still know where it is pointing? JoeAnd:
From: firstname.lastname@example.org (Clay Sherrod) If the motor is the same input voltage and SAME RPM coming out it will do fine...you might have a bit of a problem placing the motor into the space allowed with the scope however. Just make sure of the r.p.m.....you can check by putting a large cardboard disk on the end of the shaft and timing the revolution of a white dot you paint on its edge from one point all the way around to the same point again....I actually have forgotten what the r.p.m. of the tiny Meade motor is...however, you CAN use the RA motor as a test to determine since they are the identical motors in both RA and DEC.And:
What is the proper grease to use when lubricating the gears and all? By the way... My Meade AC adapter is not putting out what it should... I'm off to Radioshack to buy another, maybe this is the motors problem... Joe RodricksAnd:
Joe -by "not what it should...." how much are we talking about? Indeed, if the voltage is low, this could very well slow down response time, but keep the voltage between 12V and 15V for consistent (and safe) operation. Clay SherrodAnd:
As high as 15? I was thinking 12-13.5. The more the merrier. Mine is putting out 9.6. I never would have checked if you didn't mention that. What kind of grease should I use to lube the gears? JoeAnd:
White lithium or Mobile 28 Red Avionics grease. Yes, 15V is optimum for good dependable operation. ClayAnd then:
15V, I can do that. Any idea on howmany Amps she pulls ? After I lube her up and give her the new juice, I'll let you know how she preforms. JoeAnd:
From: email@example.com (Clay Sherrod) All you will need will be about 1 amp maximum...that is actually too much, but it will be fine. I highly recommend that you put an in-line fast burn fuse in the line however if you are going to put something together. Best of luck!And from the Autostar expert:
From: firstname.lastname@example.org (Richard Seymour) > I've noticed a considerable delay in the dec drive's response time. > This is not the typical gear lag noticed when changing drive > directions. It seems there is any where from 1/2 to 1 1/2 seconds of > delay from when I push the AustoStar's button and when the motor > actually powers up. Question: does it happen when you use the small Hand Controller instead of the Autostar? (assuming you have one) If it does -not- happen, then it's an Autostar thing, not scope-base. If it's an Autostar thing, some do exhibit "Slow buttons", caused by any number of factors (one of mine is dreadfully slow, the other is snappy). One of which is dirt between/on the rubber key-backs and the Autostar's circuit card which senses the presses. Clean with a dry cloth or Kleenex. And we're talking ETX90 here, right? Then you could try swapping the Dec and RA motor connectors where they plug into the power panel, and see if the symptom moves to the other axis. IF it -doesn't- move, it's the DEC unit. IF it -does- move, again the finger of blame points at the Autostar. (or the cable.. flakey connectors could delay the motors' understanding of the pulse sequences) When you've got the plugs swapped, only the main slew keys will be useful... any Alignment or GoTos will try to smash the telescope into the base... test with RA nd Dec clamp loosened. good luck --dickAnd this:
From: email@example.com (Richard Seymour) Joseph Rodricks wrote: > > 15V, I can do that. Any idea on howmany Amps she pulls ? An ETX90 (or at least: mine) only pulls 500 ma or so. (my 500ma RadShack lump feeds it nicely, measured voltage remains above 12v) I would worry that you're seeing the Meade supply only put out 9v. That -may- mean that something is drawing FAR too much current and consequently pulling down the Meade power lump's output (one -benefit- of an unregulated supply is that it won't move heaven and earth (or burn bridges and circuit traces) to keep its output up at the rated level). It's also possible that the Meade lump (are they passive or switching?) has lost a rectifier in a bridge, so that you're measuring a half-wave output, where the meter might be averaging the waveform and giving an incorrect number (i.e. it -could- be peaking over 12v, but the average "DC" value is around 9v) or: why i like oscilliscopes... have fun --dick
Subject: Meade 90-EC Making some weird noises when using the controllers Sent: Sunday, June 9, 2002 13:11:37 From: Mikelad1@aol.com Great site (Never heard that one before, I'm sure) I looked in the archives for the solution to this problem but I could find it. I bought my Meade ETX-90EC just yesterday on the 9th and I'm having a great time with it but I noticed that while using the controller that comes with the scope, or with the Autostar 497 controller the telescope will make some noises while I'm not pressing any buttons on the controller to move the scope. It kinds of sounds like the gears are trying to move. It makes this noises continuously until I turn off the "off" button on the base of the scope. Other than the noise everything in the scope is working. Any help on this problem would be greatly apreciated. Thanks, Mike MonahanMike here: See "One of the drive motors runs continuously but I don't see any movement of the telescope tube. Is something wrong?" on the FAQ page.
Subject: re: weight? Sent: Friday, May 31, 2002 23:26:36 From: firstname.lastname@example.org (Richard Seymour) To: email@example.com Hi, Joe... long time no read... > added weight, better tracking and GoTo's... Ya know? I wonder if you're seeing three effects: worn main Dec bearings (so they're sloppy), a slightly displaced worm drive, and inertia. The added weight forces the Dec axles to -stay- down in their bearing sleeves, and that, in turn, keeps the "big" gear fully engaged with the worm. Hence better control of the motion. Toss in the mechanical damping effect of the added mass smoothing out the jiggles and jerks of the drive, and you've probably got it. (now, of course, i could turn the screw and say: the bearings might be so -worn- due to excessive loads... but that'd be mean.) In my ETX90ec i improved the worm's drive by slipping a small shim of file folder cardboard behind the worm's cast metal holder, which pressed it -ever- so slightly more into the gear teeth. Slop dropped from 3 degrees to 1. have fun --dick
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