Meade GPS loosing its position mid viewing?

[Rols]

anyone have a clue why my GPS on my lx200 looses position during a session.

mains powered, Stationary but Alt AZ mounted. no mass weight from EP addons.

it can happen in 10 mins or 3 hours there is no consistancy to it at all...i will track around a little then tell it to goto anything and i point in completely the wrong direction and it can truely be in the opposite direction as if mirror imaged, its not just a few inches off the guide its a whole 180 degrees off target. it dont happen every night it just happens when it likes.

anyone else suffered with this or have an answer or theory for me?

[Ben Ritchie]

Mine used to do this, but only when battery powered - it didn't like any dips in voltage, and would do all sorts of runaway slews and bizarre goto when the power dipped. I know you say 'mains powered', but is it a regulated supply or one of the cheap 12V converters that can't supply consistent output? That would still be my first guess.

Is it balanced? i.e. if you release the clutches, does the OTA stay put? Could the clutches be slipping? Otherwise, not sure, but sounds very much like my power problems.

[Capricorn]

Tend to agree that it sounds very much like a power or connection problem.

There are enough GPS satellites up there that it will have data from a few always. You're not shielded by trees or houses are you?

Also once it has the data I would have expected the scope to use internal data with regular updates from the GPS systems. So even if lost it should maintain itself.

A power dip or loss sounds most likely.

[Rols]

Thanks for your opinions guys.

i'm not sure were on the right track though, i have a Revelation 12V 12mA PSU

that seems to be doing what it says on the tin according to my meter.

i have no trouble with slew on demand operations!

As far as ballanced goes this thing has never been ballanced, if i point the OTA forward 90 degrees straight from base the primary weight and gravity take over as soon as the clutch is released. On the other hand i do have houses around me but that has never stopped my SatNav picking up a good strong signal at the front of the house.

is there a test i can invoke on the GPS from the handset? or any other kind of test i can perform on the mount?

Thanks for the help.

[Ben Ritchie]

I thought that the GPS just gets position/time at startup, then isn't used - not certain though, but it seems a bit unlikely to me that it would think the location had changed during use.

Power problems are subtle, and it may seem fine for hours - just takes one blip to confuse the electronics. Seen this on both my LX200 and then a HEQ5, the latter would work fine for hours and then lock up. So it's certainly the first thing i'd try and eliminate.

Slipping clutches are possible, if unlikely. I ran my LX200 in balance, so if you released the clutches the OTA just stayed put - too many horror stories at the time about out-of-balance OTAs stripping the plastic gearing. Otherwise, dunno really - faulty encoder somewhere?

Have you done the usual 'train drives'/'calibrate sensors' routines (or whatever they're called, four years or so since I owned a LX).

[Rols]

?

Have you done the usual 'train drives'/'calibrate sensors' routines (or whatever they're called, four years or so since I owned a LX).

No Ben i havent, maybe that should be my next step, i was a little apprehensive about trying to calibrate something that was only new 2 months ago. but i suppose i should have known better. time to familurise myself with the step by step i suppose. thanks for the input. i'l come back to the thread to reprt my findings after callibration of everything it will let me do.

[Ben Ritchie]

To be honest I doubt that calibrate sensors/drives will help your particular problem, but in general it's well worth doing as it made my LX200 pointing significantly better - make sure you use a cross-hair eyepiece or similar, because it really needs to be as accurate as possible for maximum effect.

If it's just a couple of months old, have you tried calling Telescope House? I've always found their support very good

[michael8554]

You said your power supply was 12v 12mA, hope that's a typo, I'd guess you need 1200mA or more likely 2000mA to drive a LX200?

Regards

Michael

[Rols]

@ Ben - i think your probably right i will give them a call next monday on my day off..

@ michael - your right, typo! i was thinking 12Amp typing 1200mA i will ask the question on monday next and confirm in this thread later. i just took it for granted i was sold what i requied..