Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
OK, I popped off the plate and cover and realized that the twitch in the gear was coming from the rectangular gear housing preceeding the belt. The twitch is only noticeable on the second speed (like second from slowest) and occurs every second. Has anyone every taken this rectangular housing apart? It has the motor on one end, the manual spindle in the middle, and the belt pulley on the other.
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
Skywatchr
Carpal Tunnel
Reged: 06/03/06
Posts: 1581
Loc: North-Central Pa.
|
|
Yes, I have had the gearbox apart, and it's very tricky and you probably don't want to mess with it. But the "green tape" on the side of it is actually a cover and you can pull it off and look inside. But the noise could be caused by the worm putting a periodic "load" on the gearbox. I would still check the worm and wheel.
Jeff
--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
Highly Modified Meade DS-16 in Roll Off Roof
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650, LX200 Classic
Orange Tube C11
DayStar 0.45 with multiple ERFs
Vixen ED80sf
10" LX200 GPS SMT
11x80 Meade, 20x80 Celestron binocs (Japan Made).
Lots of Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.
And a Wife that loves it as much as me!
|
Skywatchr
Carpal Tunnel
Reged: 06/03/06
Posts: 1581
Loc: North-Central Pa.
|
|
Oh, and make sure the belt is taught (not over tight), if it's a bit loose, the cogs themselves can cause funny noises.
Jeff
--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
Highly Modified Meade DS-16 in Roll Off Roof
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650, LX200 Classic
Orange Tube C11
DayStar 0.45 with multiple ERFs
Vixen ED80sf
10" LX200 GPS SMT
11x80 Meade, 20x80 Celestron binocs (Japan Made).
Lots of Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.
And a Wife that loves it as much as me!
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
OK. Yeah, what is that green tape? It looked like one-sided stuff and I was able to pull off the backing (?). I will definitely double check to see that the belt is not pulling a load...your advice is priceless here!!!!
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
OK. I pulled off the green tape and the first of the gears that looks maybe directly connected to the motor is the source of the problem. This will rotate about 30 degrees while the second gear is not moving and then the second gear will "snap" into motion.
Out of curiosity, are the encoders for the lxd750 on the axis or in the geartrain? If in the geartrain, this could explain why the pointing accuracy is so far off.
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
If this is in fact the problem, does -- I am holding my breath here -- meade still service these?
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
Sorry for the repeat posts. Just checked out a site called http://hometown.aol.com/ccdastro/decfix.htm
where this guy shows the guts of the gearbox. My prelim conclusions:
1. The encoder is on the motor directly! Thus if the gears are faulty the pointing is too.
2. Crazy thought...cant I just get a "typical" meade gearbox? and swap out gears...this will be like brain surgery but seems possible with time and care.
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
John Carruthers
Skiprat
Reged: 02/02/07
Posts: 1705
Loc: Kent, UK
|
|
The drive train is very similar to the LX200 mount, there is an uprated belt drive conversion by WarpsDrive but AWR can make up a bespoke gear /stepper drive which also does away with the existing encoders but keeps the 'zero point' sensor. We have an LXD750 in the shop at the moment getting just such a makeover.
--------------------
Jc
ATM 10" F6.1, 1/25th wave spec (max wavefront error +/- 1/12.6 in zone 4 of 6, sodium light )
6" F7 spec
127mm F9.4 Refractor
10 x 50 bin
ETX80 (finder)
Canon 20D
and a curious mind
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
Jc,
Do I just contact AWR directly, or are you involved with them?
-Peter
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
John Carruthers
Skiprat
Reged: 02/02/07
Posts: 1705
Loc: Kent, UK
|
|
Sorry Peter, I tried to reply last night but it seems to have got lost, yes I would get on to Alan Buckman directly, I'm just the 'part time odd job man/tea boy/ consultant (pro diem)' 
He can give you deffinite prices and expected turnaround times. Obviously there's always the unexpected, the mount shown for instance was found to need all new bearings, but nothing is done without the owners prior consent.
--------------------
Jc
ATM 10" F6.1, 1/25th wave spec (max wavefront error +/- 1/12.6 in zone 4 of 6, sodium light )
6" F7 spec
127mm F9.4 Refractor
10 x 50 bin
ETX80 (finder)
Canon 20D
and a curious mind
|
Skywatchr
Carpal Tunnel
Reged: 06/03/06
Posts: 1581
Loc: North-Central Pa.
|
|
The gearbox itself is the same as the LX200 Classic. And there are probably plenty of them floating around with "bad" electronics, and "good" gearboxes.
Jeff
Quote:
OK. I pulled off the green tape and the first of the gears that looks maybe directly connected to the motor is the source of the problem. This will rotate about 30 degrees while the second gear is not moving and then the second gear will "snap" into motion.
Out of curiosity, are the encoders for the lxd750 on the axis or in the geartrain? If in the geartrain, this could explain why the pointing accuracy is so far off.
--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
Highly Modified Meade DS-16 in Roll Off Roof
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650, LX200 Classic
Orange Tube C11
DayStar 0.45 with multiple ERFs
Vixen ED80sf
10" LX200 GPS SMT
11x80 Meade, 20x80 Celestron binocs (Japan Made).
Lots of Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.
And a Wife that loves it as much as me!
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
OK, seems like I have 3 options...ship to UK / AWR, ship to astronomy shoppe, or try to get a used gearbox and do it myself. At the risk of being reckless, I will probably try to just get a lx200 fork with a gearbox.
Again, I typically hand out at AM but the level and quality of information here on CN is astounding. Many thanks to all who made suggestions.
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
CHASLX200
professor emeritus
Reged: 09/29/07
Posts: 740
|
|
I had both the 650 and 750 a few years back, seemed they had a mind of their own and would just go nuts and bump into the tripod or crazy stuff. All in all i liked both the 650 and 750.
Chas
|
Skywatchr
Carpal Tunnel
Reged: 06/03/06
Posts: 1581
Loc: North-Central Pa.
|
|
Astronomy Shoppe doesn't repair the motors. Only the electronics. Well actually they send them out to another guy to repair for them. They're just the middle-man. I'll do some digging, I may have a good gearbox from an LX200 Classic here somewhere. You'll have to dismantle the gearbox to change the manual slo-mo knob, you'll have to change the intermediate shaft from your old gearbox to the replacement LX200 Classic box.
Jeff
Quote:
OK, seems like I have 3 options...ship to UK / AWR, ship to astronomy shoppe, or try to get a used gearbox and do it myself. At the risk of being reckless, I will probably try to just get a lx200 fork with a gearbox.
Again, I typically hand out at AM but the level and quality of information here on CN is astounding. Many thanks to all who made suggestions.
--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
Highly Modified Meade DS-16 in Roll Off Roof
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650, LX200 Classic
Orange Tube C11
DayStar 0.45 with multiple ERFs
Vixen ED80sf
10" LX200 GPS SMT
11x80 Meade, 20x80 Celestron binocs (Japan Made).
Lots of Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.
And a Wife that loves it as much as me!
Edited by Skywatchr (08/31/08 03:09 AM)
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
Thx Jeff!
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
Skywatchr
Carpal Tunnel
Reged: 06/03/06
Posts: 1581
Loc: North-Central Pa.
|
|
Pete, I was unable to find the one I was looking for. It was a DEC unit and would have been what you need. But I must have already given it away, sorry. I do have a couple of brand new LX200 Classic RA assemblies. But try and find a used DEC assembly if you can. It will already have the slo-mo shaft sticking out of it. I'm not ready to part with these RA assemblies just yet. Unless I get a real good offer. 
Jeff
--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
Highly Modified Meade DS-16 in Roll Off Roof
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650, LX200 Classic
Orange Tube C11
DayStar 0.45 with multiple ERFs
Vixen ED80sf
10" LX200 GPS SMT
11x80 Meade, 20x80 Celestron binocs (Japan Made).
Lots of Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.
And a Wife that loves it as much as me!
|
Skywatchr
Carpal Tunnel
Reged: 06/03/06
Posts: 1581
Loc: North-Central Pa.
|
|
Pete, just for something to try, take the motor assembly out and "flush" the gearbox with WD40 (or equivalent) and let it drain off upside-down overnight. Then put a few drops of 3 it 1 oil on the gears and shafts and let it sit about a half an hour (so it "creeps" into the shafts). Replace the "green tape" with a piece of stiff cellophane, or other heavy tape to keep dirt out. Put it back in and give it a test run. It may just be a lack of lube causing it to "jump" like that.
Jeff
--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
Highly Modified Meade DS-16 in Roll Off Roof
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650, LX200 Classic
Orange Tube C11
DayStar 0.45 with multiple ERFs
Vixen ED80sf
10" LX200 GPS SMT
11x80 Meade, 20x80 Celestron binocs (Japan Made).
Lots of Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.
And a Wife that loves it as much as me!
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
OK, I will do. I have an Ad up on Am for the motor as well.
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
Peter Glus
super member
Reged: 05/08/06
Posts: 119
|
|
Stared at the gears for a LONG time over the past week, and decided this was too big a challenge to touch anything. Besides, i got only one response for spare parts on AMart and that was for specfic gears. Am bummed, since there also seems to be no stateside shop. I will contact the UK shop mentioned above to see if thats an option.
--------------------
Very Urban Astronomer in NYC
C14, Vixen 140NA, and a LXD750
|
Previous
Index
Next
Threaded
[Re: 
Edit
Reply
Quote
