etx 80 issue

[super_stroke]

Hi everyone. I'm new to the forum and relatively new to telescopes. I bought a meade ETX 80AT last year. I used it most of the summer and put it in the box for winter. I got it out last week and noticed as it makes a rotation left or right about half way thru it slows down and sorta chatter's. It's really bad if its slewing very slowly. The motor still runs but it stops turning for just a second and pops (doesn't literally make a pop noise) forward and does it over and over until it reaches about half way thru and then its nice and silky. It kinda acts like something is binding or bent. I took the bottom half off to look around and didn't really see anything that could be wrong. But while I was in there I went ahead and dabbed some light grease on the gears but it still does it. Anyone else have this problem or have any ideas? Think's Bill.

[schwimmair]

I have had two ETX-80's and they have worked flawlessly.

Some obvious things to check would be:

fresh batteries
make sure the clutch is tight
try slewing the scope with different slew speeds and see what happens

If the scope is under a year old I would return it to Meade and have them send you a new scope. If it is older than a year some debt/credit cards offer a additional year warranty and may be covered.

I am sure some techies will chime in on some other stuff to try.

Schwimm

[redlined_b16a]

Sounds like it's running into the stops
Are you sure you are setting it into home position correctly?
Assuming ur using the autostar

If you are hitting the stops,be careful it's not good too do so,as soon as I hear the motor slowing down I shut it off but once I learned to set it up I never hit the stop again.
I'm not implying you don't have it set up correctly just visit the Meade site they have a vid section showing hiw to set it up.

My 125ec is loosen the clutch,rotate counter clockwise until it hits the stop,then rotate clockwise about 1/4 turn(when the Meade logo on the fork is centered over the base on off switch panel)
The on off switch should be facing west,scope north

Keep us updated

[jimt]

The ETX 80 doesn't have hard stops in it. That starts with the 90mm. My guess would be that a wire has gotten in the way. Either that or some sort of trash has gotten in the gears. Something is causing it to bind. You could try turning the mount several revolutions in both directions to redistribute the grease and maybe work out the trash if it is the problem. If you wind up cutting a wire into, then you will know what the problem was, and it will be easy to fix.

Jim

[super_stroke]

Sorry guys I've been out of town. I haven't had a chance to mess with it. It does have new batteries, energizer max I think, the clutch is tight. I took the little lever of last summer and moved it one notch because it wouldn't tighten it much, I thought anyway. It slew's fine at higher speeds but at the really slow speeds is when it does it. Set up- I level it with the level it came with and point it north. I had the bottom half off last week and there was no dirt anywhere or wires rubbing. I also loosened the clutch and rotated it by hand both directions and I can feel it tighten up in the same spot it starts to act up when it slew's. I won't be able to look at it farther till Fri but I'll check in later this week. Thanks for help so far. Bill.

[jenniferchristine]

Strip it down and clean off the glue that passes for grease - then relube it with a lithium grease.
At the moment it sounds like it is swimming through a sea of crusty gloop

[schwimmair]

super stroke, I remember reading somewhere that some ETX scopes have a problem with the Manual Setting Circle rubbing and causing binding during various stages of slew. Make sure your DSC is not doing this. If it is trim the portion of the DSC that is causing the problem.

It's a long shot but stranger things have happened.

Schwimm

[DirectionalDriller]

Mine is new and it chatters a bit when it is at slow speed, ie. on a target and slewing to the rotation of the earth. I think that may be normal.

[Joe Lalumia]

Check the central bolt after you take off the bottom-- could be just TOO TIGHT. Anyway an inspection is in order.

On my ETX 125PE-- which I bought used-- it would spin and then hit "something" which would slow it down and if you helped it along it would continue as though nothing was wrong. I sent it to Dr. Clay for a supercharge and he found a NUT underneath the bottom plate that had been left INSIDE apparently during manufacture.

You could not see the nut as it was underneath the metal plate --- only a complete dis-assembly found it,.

[Stew57]

The etx80 is a little weird, there is a plastic nut that presses against the bottom of the base that takes the space out, and has a castle top that keeps the clutch tightner from turning. If it is too tight it can cause stickiness in rotation, if too loose the nut will turn when you turn the clutck lever and the clutch will not engage. How tight it tight enough is the question.

To fix remove bottom cover. Remove clutch lever. Unscrew long bolt that the clutch lever was attached to (you may have to hole the round clutch nut on the bottom after it disengages from the plastic castle nut. Now you can loosen the castle nut to a tight finger tight and put back together in the opposite order. It is really easy to do and you don't have to open anything up.

The bad thing is the unit uses teflon bushings for bearings and even at best with proper lubrication it is not going to be as smooth as the ETX90 or ETX125 or other better made units. That is the reason the 80 never had the option of polar mode. The engineers felt the additional weight of the increase in aperture caused too much friction in the bushing arangement. The 70 was considered marginal as it was.