What should I do with my LX200??

[philipok]

thanks Mark -  it's a right old debate..  what I'm after is doing wide field, 30s-1m exposures with my 61mm Zenithstar, so if I can get to that stage I'll be happy.  i.e, a step up from my DSLR..

Also I've cemented a massive pier in my obsy for the Meade so it would be a pain to have to change it all around!

 

Philip

 

[spillage]

Could you not make an adaptor to fit another mount onto the existing pier? Not sure of the mounting details on the eq8 but my neq6 sits on two old disc brakes from my old golf.

The meade will be okay but due to dec rotation you will end up having to crop out allot of data.

I nearly brought an old meade last year. 12" one (maybe a lx200) but it had sat way to long and after a good inspection decided that looked to much like hard work getting the thing apart.

My eq6 on the other hand is a doddle to strip down.

Have you tried asking on the cloudynight forum. It more American based and I am sure they are more into meade's so might be able to help.

 

[Davey-T]

Like all mass produced stuff you can't really condemn all Meade mounts based on other folks experiences especially as they only tend to post complaints which simply get rehashed by those who have never actually owned one 😁

Mine is pretty old but has been to bits and had a bit of fettling to get rid of some backlash and depending where its aimed can do reasonably long exposures.

I do find that I have to alter the balancing depending on dec position and have a 3D balancing system for this and fine tune it to do short north only corrections, also contrary to popular opinion I use short guide pulses of 1.5 / 2.0 seconds and still using PHD1.

I generally only take 300 sec images with the SCT but the longest I did was 30 minutes on the Thors Helmet Nebula as a test after a bit of fettling, with 100mm f/6 piggy backed I usually do 10 minutes OK.

So I think it's worth persevering to get results from it as is, presumably it's not old enough to have plastic gears which started the original problems.

Dave

 

[philipok]

Dave - i intend to work on it until I get some good results.

terms like 'fettling' the gears scares me a bit!  i'm not I'm up to messing around with the guts

I bought it in late 2006, so I'm assuming it has metal gears rather than plastic (and therefore kits such as the Peterson tune up one are not necessary)

Philip

 

 

[Davey-T]

They changed the way the motor is mounted, no idea what the date was, mine has the later sideways hinged assembly, earlier ones were hinged at one end, don't know when they changed to metal gears, it's easy enough to remove the dec cover and see what's going on, you can see how the worm is meshing and adjust the tension and run it without the cover on.

Dave

 

 

[Davey-T]

Piggy backing stuff is fine as being fork mounted once balanced the weight doesn't bother it, here's mine with 100mm refractor and Lunt LS60DS on it.

Dave

[philipok]

btw, here is my PHD2 log from the other night.. it's pretty dire until towards sections 39 and 40, after I'd put in two cycles of PEC training and got the polar alignment down.  Also I was losing stars with fogging up of the scope..    I think my problem is I'm giving it enough time to settle - would welcome any comments

PHD2_GuideLog_2020-06-01_221045.txt

[michael8554]

Here's your first Calibration:

Those lines should be straight and at 90 degrees !!

I don't have an explanation for that I'm afraid.

The red cluster halfway along the line is where the mount is hardly moving in Dec for 20 or so steps.

Although the mount is set to 10arcsecs/sec on both axis, RA is Calibrating at that rate, but Dec is actually Calibrating at only half that rate.

 

Here's your second Cal:

Now the lines are trying to be 90 degrees apart, what was changed between these two Cals ?

These are not normal LX200 GPS behaviour.

Again RA is Calibrating correctly in 19 steps, but Dec is taking 47 steps, and again that even bigger cluster of non-movement.

Plus those return pulses S0 to S4 that are way off-piste !I

Is the Dec clutch tightened ? The mount shouldn't move if you gently pull down on the front of the OTA.

Perhaps one of the Dec gears needs tightening on it's shaft, not uncommon,

Your 4 second exposures are too long, 1.6 seconds was recommended in one of the Guide Assistant runs.

Michael

Edited June 4, 2020 by michael8554

[philipok]

thanks very much Michael - 

i hadn't clocked the recommendation on exposures in GA 

By tightening the gears & clutch - is that achieved by opening up the fork arms?  or do i need to go into the base plate?

 

philip

[Davey-T]

Its pretty easy to check the dec  operation, I don't know if the Peterson instructions are online, would be good if they were as they have all the info you need to sort the dec out.

I may have a copy somewhere, I'll have a search for it later.

Dave

[Davey-T]

32 minutes ago, philipok said:

By tightening the gears & clutch - is that achieved by opening up the fork arms?  or do i need to go into the base plate?

The clutch is metal on metal with a coating of grease and benefits from a clean and re-grease after many years, you can also replace the grease with either a Peterson gasket or a DIY one.

Dave

[michael8554]

Hi Dave

-Dec_backlash.doc

There's some confusion in the numbering so read carefully !

Loosen and remove the Dec clutch screw while holding the OTA, and carefully allow the OTA find a balanced position.

Remove five screws holding the cover on with a 3/32" Allen key. (Careful when replacing those afterwards, the plastic they screw into can break, they only need to be finger tight to hold the cover.)

Screw the Dec Clutch Screw back on with the OTA back in a normal position.

Now you can slew Dec and look for the worm jumping, worm gear damage, etc.

The worm is spring-loaded onto the worm gear, and there should be a 1/16" minimum clearance at the end of the Allen screw "Rack Swing Limit PIn" when you slew through the normal range of Dec movement.

You can reduce that if you see the worm jumping, maybe when making fast reverses, but never have zero clearance.

Michael

[Davey-T]

I reduced backlash between the gears with a bit of judicious work using a small rat tail file.

Dave

The worm gear on mine was nearly out the inner face of the wheel so I put a small packer behind the motor assembly to get it more central.

Edited June 4, 2020 by Davey-T

[Davey-T]

change from plastic to metal gears was August 2005.

If you do take it apart it's worth fitting one of these.

Dave

https://www.rothervalleyoptics.co.uk/peterson-ez-clutch-upgrade-kits.html

[philipok]

thanks very much everyone - I'll take a look (carefully) and see if I can see any obvious problems 

[uhb1966]

Hi Philipok, are you connecting phd2 via EQMOD? If yes, did you correct EQMod's guide speed from 0.2 to 0.9?  Best, U. (PS sorry for being Cpt Obvious)

Edited June 7, 2020 by uhb1966

[michael8554]

6 hours ago, uhb1966 said:

are you connecting phd2 via EQMOD?

EQMOD is for EQ mounts, not Meade LX200GPS mounts.

Michael

[philipok]

hi folks - further to your (Dave and Michael's suggestions) I opened up the DEC arm..  looked ok to me (attached pics)

- relieved to see I have brass gears..  

- cleaned the two gears with a toothbrush to get crud out.  the lower one had ever so slightly some left-right play, but I could not tighten the pin that much for risk of damaging the screw - seemed tight already.  top gear seemed fine and well held in.

But I could definitely see the backlash as I played with the gears manually.  

The main DEC gear and worm seemed ok.  I noticed that when I turned the DEC manually the main gear wanted to push out towards me (in fact it pushed off the clutch plate at one point). not sure whether that's normal - i guess in normal usage the cover is preventing it from moving outwards.

Any idea whether it's worth tightening or loosening the rack pin spring screw ?

not quite brave enough to remove the mounting bolts and try the second step mentioned in the instructions Michael sent

Initial scouting complete..  I'll wait for a clear night and try the guiding again..

Philip

 

[michael8554]

13 hours ago, philipok said:

The main DEC gear and worm seemed ok.  I noticed that when I turned the DEC manually the main gear wanted to push out towards me

Shouldn't do that with the clutch knob tightened.

Does the worm wheel move in and out if you gently lever at the circumference ?

 

13 hours ago, philipok said:

Any idea whether it's worth tightening or loosening the rack pin spring screw ?

Adjust as I described.

[philipok]

thanks Michael - just so I'm clear - the allen screw on the spring should be screwed further in, but to about 1/16" - i.e pushing the spring tighter?

[Davey-T]

Leave the cover off and just refit the tensioner knob and observe what's happening when PHD is calibrating, mine is weighted to north guide only and only does a couple of backlash compensations before heading north.

Dave

[Knight of Clear Skies]

"What shall we do with the LX200?

What shall we do with the LX200?

What shall we do with LX200?

Er-lee in the morn-in!

Chuck it in a van and [removed word] the collimation,

Chuck it in a van and [removed word] the collimation,

Chuck it in a van and [removed word] the collimation,

Er-lee in the morn-in!

What shall we do with the LX200?

What shall we do with the LX200?

What shall we do with LX200?

Er-lee in the morn-in!

Leave the cover off and refit the tensioner knob,

Leave the cover off and refit the tensioner knob,

Leave the cover off and refit the tensioner knob,

Er-lee in the morn-in!

Shouldn't do that with the clutch knob tightened,

Shouldn't do that with the clutch knob tightened,

Shouldn't do that with the clutch knob tightened,

Er-lee in the morn-in!"

[Davey-T]

23 minutes ago, Knight of Clear Skies said:

Shouldn't do that with the clutch knob tightened,

?

Dave

[Knight of Clear Skies]

2 hours ago, Davey-T said:

?

Dave

I was going for metre over sense, although I doubt I've succeeded at either.

[ollypenrice]

42 minutes ago, Knight of Clear Skies said:

I was going for metre over sense, although I doubt I've succeeded at either.

The metre requires us to hear, 'Lex200,' no?

Olly