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Last updated: 22 December 2002
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Last updated: 22 December 2002 |
Subject: ETX 125 Saga Continues Sent: Friday, December 20, 2002 9:52:18 From: edelmann@hcst.net (John Edelmann) You will probably recall that I had this ETX125 which arrived 11/6/02, only to find that the flip mirror came apart as soon as the mechanism was operated? Well, the hilarity of the situation (and no, I'm not taking this well, despite the timbre of this note) just gets better all the time. It was returned via UPS to the shop in Irvine on 11/12/02, and received 11/19. It was finally repaired, but I had placed a hold on it, so that I could send it to a vacation stop over the holidays (we're leaving for FL today). Unfortunately, colossal screwups that they are, they "forgot" or didn't have the capacity to properly place a hold so I could call to redirect it in time, so now, my scope is headed to my place of employment, arriving 12/26, most likely, because they sent it by ground, instead of 2-3 day air. So... just for the record, I called today and found that it couldn't be redirected in transit, since it's destined for a depot in Ohio direct for California.... no inbetween spots. I really wanted this while on vacation, not so much as a Christmas present, but because I could spend unfettered hours getting to know it. But alas, I'll get it when I return to work on 1/4. So... for my troubles, here's the scoop: Original order from Discovery Channel: $1235 (includ tax and shipping) Less $36 shipping (DChannel allowance for delay of receiving original LXD55 8") Less $100 discount (DChannel allowance once they found I had to return it for repair) Less $100 credits from DChannel certificates) used to purchase Dew Shield and variable polarizer) Less $50 (#1 Filter set direct from MEADE for their ineptitude in following shipping directions) --------------- So in the end, the $1235 venture (were I to have purchased all of the items I got individually/at cost) has only cost me about $900. Not a satisfactory replacement for not having the scope, but better than nothing, I suppose. I suppose I could look on the bright side: at least I don't have to waste room in the van to Florida with all of the accessories I would have otherwise taken down... One of these days, hopefully I'll have something really positive to report. Merry Christmas/Happy Holidays Mike and all... John EdelmannAnd:
From: drclay@arksky.org (Clay Sherrod) Interesting...amusing but not particularly "funny." I sure hope things get better for you. Have a Merry Christmas and a "better New Year" astronomically speaking! Thanks for writing! Dr. Clay Arkansas Sky Observatory www.arksky.org MPC/cbat Obs. H43
Subject: re: Autostar cable colors Sent: Wednesday, December 4, 2002 20:57:09 From: rseymour@wolfenet.com (Richard Seymour) To: gillmj@alum.rpi.edu Your discovery of the Autsotar's cable colors it the correct way for them to be arranged. The "A15" and "A16" just identify which area of the plastic modling equipment produced those pieces. Cables can be built with all possible shuffles of wires. The Autsotar cable happens to be wired in the same order as regular, and 8-wire office, telephone cables (peer at either your telephone line cord, or the handset cord, they both "reverse" the colors). If you look at computer networking cables, you'll see that one pair of colors even bridges over another pair's colors. (no, you cannot use computer network cables for your Autostar) have fun --dick
Subject: Mechanical "Tech Tips" Tune up for ETX-125 with New construction Sent: Wednesday, December 4, 2002 19:50:32 From: AlanM@peoplepc.com (Alan McDonald) I just purchased a barely used ETX 125 scope through e-Bay, and was all set to perform the "Tech Tips" performance enhancements recommended by Dr. Clay Sherrod, only to find out that the scope is of the new construction. While this construction is probably stiffer and "better" than the old construction in many ways, it is still appears to have quite a bit of slop in it - especially in the ball bearings themselves! I have searched your sight looking for equivalent tips for the mechanical functions of the scope (dec and RA clutches, in particular), but have not found any. Do they exist? I feel that the clutches are still probably slipping from excess grease - it does not take much pressure on the OTA to make the clutches slip once they are engaged to a "firm feel", and I fear that it will be easy to lose alignment in the current situation. The RA axis seems particularly vulnerable to this (it is hard to notice much difference between engaged and disengaged, although the scope moves well when fully engaged). I am reluctant to get into the scope without some guidance. Of course, I could just make arrangements to send it to Clay for a Supercharge! Also, the dec clamp has something very peculiar about it, and since the scope was used, I do not know the full story. It looks like there is an loose hub ring spacer in it, the exact diameter and wall thickness as the hub that the plastic OTA support arm rides on, with squared edges and about 2.5 mm thick. It almost looks like an extra part, and it has clearly bounced around in there a lot. Without it, the dec clutch won't lock right, but it just can't be made to line up right in there - if it supposed to be in there like that, it is very flaky, as the load bearing surfaces can't be made to line up consistently. I'll need to take some photos of it and describe it in a later e-mail, as words do not do it justice. But I have found that a couple of metal fender washers under the aluminum setting circle work really well in it's place . . . more to follow on this when I can get a few pictures (I think I need a digital camera!). By the way, quick star tests show that the optics appear to be fantastic! I really look forward to getting this up and running to it's real potential . . . . Thanks for your great site and outstanding help (I have contacted you about my ETX-60 in the past).Mike here: There are no updates for the newer models.
And:
From: sherrodc@ipa.net (Clay Sherrod) I do not recommend working on the new model....for many reasons and that is why I have NOT put out any instructions on how to do so. Meade has made these new scopes almost "tamper proof" with dangerous consequences for those who do attempt modifications and/or tune-ups. They are not easy to work on and there are many safeguards that are now in place to prevent the casual "home mechanic" from tampering with the workings of these scopes. Dr. Clay Arkansas Sky Observatory www.arksky.org MPC/cbat Obs. H43And:
From: AlanM@peoplepc.com (Alan McDonald) OK, but it is rather troubling that Meade would make a major change to the scope, and not get it as mechanically solid as Clay describes in his Tech Tips. One would think that if they were going to all the trouble to re-tool it, they would have made sure that the results were at least as good as well built version off the old tools. But I digress. I accepted that I could not do Tech Tip 1 to get the clutches cleaned up (even though I think it needs it), but I was desperate to find a way to do Tech Tip 4 (eliminate much slop form the dec axis). So I decided to mess around a bit with the dec axis, to see if I could find where some of the slop was. I removed the OTA to see where the slop was coming from. I was pretty impressed with the way the tube arms attach to the tubes, as there was very little movement there. But the way the tube arms mount into the fork was another matter all together. There was slop in three places:1) the shaft within the bearing (both sides), and 2) side-to-side slop with the arms and OTA assy between the fork arms , and 3) the bearings are full of slop, both laterally and rotationally about the central axis. Number 2 was particularly troubling, as it induces more gear backlash in the system, and it will vary as the load on the tube changes (especially since I love the Meade 14mm SWA eyepiece, and it is heavy). Number 3 is pretty bad too, as it magnifies everything else, and allows the whole OTA to basically wiggle around inside the forks like it is attached with bungee cords (a little exaggeration, but it gives you the right visual idea). The same corrective action fixes both the second and third kind of slop, and is pretty straightforward. This can be done entirely on the slave side (setting circle with numbers), so that you do not have to mess with the dec drive at all! This consists of two actions 1) spacing the tube support arm further inboard with a fiber washer (which I made from thin cardboard) on the shaft, and for good measure, 2) loading the shaft onto the bearing, by building a sleeve over the shaft with nylon washers. This sleeve must end up sticking out about 0.5mm beyond the end of the shaft, so that when the declination circle is secured, it loads the shaft into the bearing. Amazingly, the only thing that keeps the shaft in the bearing is the outward pressure of the OTA - there is over 5mm of shaft sticking though the bearing , so the setting circle doesn't touch anything but the shaft. I suppose that the second part of this may be unnecessary because the fiber washer loads the shaft onto the bearing so much better than before - I might pull it out later to see if there is a difference, but the setting circle is now held so much tightly. One important note with all of this - the fiber spacer and the nylon washers must not be any wider than the bearing surface, or they will drag and bind on non-rotating surfaces. I fixed the first kind of slop (shaft in the bearing) simply, with a few wraps of Teflon tape on the shaft. That worked so well that I thought (rather stupidly) that I would see what I could do with the motor side of the fork. I must admit, that there is not much that you can do in there, other than scare yourself pretty good.. If you remove the OTA support shaft, you will hear two very scary "clink" sounds as the clutch and gear both drop into the gearbox. I thought I was sunk, but they only go a short way down, and it turns out that it is easy to get the shaft lined up and back through both items and the two bearings. About all you can do here is clean a lot of excess grease off the support shaft, and then put some Teflon tape around the inner most part of the shaft - this rides in the inner bearing, which is much larger that the slave outer bearing. This appears to have helped some. You can only do a little Teflon on the outer bearing, as the shaft has a grove cut in it that has is a keyway for a tab on drive gear - and if you leave any loose Teflon (or have enough that it bunches up behind the shaft) you run the risk of getting it caught in the gears, or sliding into the clutch. Both would be bad things. So generally, I think one should leave the dec side alone. But there does seem to be gobs of grease everywhere, including on the clutch surfaces. It sure would be nice to clean that up some . . . . . but I'm not willing to pull the gearbox out to get in there. So I now have the dec axis running really good. I just need to figure out how to get the slop out of the RA mechanism. I have not been in it yet, and I am real reluctant to go in there. But there is about two degrees of rotational slop that is not gear backlash at all. It appears to between the table and the clutch, but before the gear. With the RA clamp secured, I can manually rotate the scope a full notch on the RA setting circle. I can manually move it anywhere within this range, and it pretty much stays put. There motors never "take up the slack" in this situation, so it has to be slop before the gears. It is bad enough that I don't think I could use the scope in polar mode, because as I cross over from one side to the other on RA, the torque from the OTA would result in lost alignment. Any suggestions on the RA? Would Clay's Supercharge clean up this problem? If so, I might be inclined to do it.