Meade Starnavigator 102 - trouble slewing

[Ali G]

I am a new, new, newbie! I have bought a Meade telescope (refractor) from a friend. It's a Starnavigator 102.

At first I confess I had the scope on the arm the wrong way round!!!! I have found the ancient manual a bit heavy going. But I'm learning bit by bit.

Then once in place properly, pointing magnetic north, horizontal and all info entered correctly, Oxford, DST - no, time as GMT.....it does slew to the first star...usually Capella or Arcturus, but then slews very slowly causing the Audiostar handset to fade out. I try to press for another star but the panel just fades out.

I have tried training the drives but I don't know if I'm doing it right. The only You Tube video I could find wasn't great. To be honest this has all been in daylight with a 26mm lens on as I just wanted to see if it would work in theory.

I am a bit annoyed that I can't use another power source other than batteries. The old model means there's no port. I have tried a 12v adapter and a jack with battery clips but it doesn't work for some reason.

We had a great night looking at the moon though.

Anyways any tips greatly received. Happy stargazing you lucky lot!!

Sorry if this is completely the wrong place to post all this.

Ali G

Bristol, UK

 

[Starwatcher2001]

Welcome aboard SGL Ali. Good to have you with us.

I'm not familiar with that kit, but I'm sure there'll be a way to power it from an external source*. Do you know the spec of the adapter you used (probably written on it)? It sounds like it hasn't got enough power.

*Might involve a bit of soldering.

 

Edited May 24, 2022 by Starwatcher2001

[DaveL59]

For the skywatcher SynScan rig I think you need a 12v 2A PSU to drive it so that's probably a good number to start with. No harm getting a PSU that can deliver more amps as the rig will only draw what it needs. When the scope is moving on both axes the power demand peaks. Be sure it's a regulated PSU tho else the off-load volts can spike a bit higher than the electronics might survive.

In my case (SynScan) I either hook a mains PSU or use a LiPo car starter pack with a 12v 5A buck converter to provide a well regulated 12v since car starter packs can deliver >15v off load and I don't fancy frying electronics, the magic smoke doesn't smell all that good 😉 

[Ali G]

Hi, thank you for your replies which are much appreciated. Trouble is I don't understand all the tech speak. Can you send me a photo or an idiot's guide (with links) to what you mean. I think the 12v 2A psu is basically an adapter with a jack end. I have one but it may not be regulated and it's from China..... Or should I be trying a 12v 5A instead.

I also have a 9w battery clip which attaches to the jack and then the male/female parts on the battery pack clip inside the compartment area of the scope. But there was nothing when I hooked it all up. The car starter packs I've found are expensive....unless I'm looking at the wrong thing. Please can you bear with me as I grasp all this. I'm grateful for your help.

Finally, the slewing, is it a power/battery issue then? I need to get it outside at night and have another go.

Thanks, Ali G

Happy stargazing all!

[DaveL59]

ok, in terms of the power adaptor (wall wart etc) pretty sure the one I have is also made in China, most likely are these days, but look for the info label and it should show a solid line above a dotted one as circled in the pic below. That'd indicate that it is voltage regulated.

This one is a 5A one and it'll run my SynScan mount just fine but as I recall a 2A unit would cope too, I just prefer to have the extra capacity in case I want to add other items to the scope that need power.

In terms of a car starter rig, in this thread this is what I put together to run my EQ5 12v SynScan GoTo mount.

I bought the LiPo pack off Amazon during one of their sale/price reduction periods and being lazy bought pre-made plug/lead parts to create the flying leads rather than fiddle with soldering plugs on wires. This give a light weight battery pack that via the buck converter delivers a regulated 12v with up to 5A current draw. There's any number of ways you could go on setting up a battery power unit with different up/down-sides. Lead battery units are likely cheaper but also heavy and the battery needs to be regularly charged else it'll fail quickly. Lithium is more expensive but is light and has less requirement for maintenance charging.

Initially tho for your needs, perhaps a good power adaptor (say 3A or better) would be a start. Then you can establish if there's any other issue before spending further. When I first got the SynScan mount I did test indoors in daylight at first. That meant I wasn't fumbling in the dark trying to figure stuff out and could also observe what the mount was doing. Turned out it had some issues with drag/bearing stiffness on one axis that would have been harder to spot in the dark. No need to concern yourself with if it found the target it was seeking, just go through the fine adjust process as if you were doing it for real, then select the next target and see what the mount does, repeat until it completes the 2 or 3 star alignment and then see if it'll realign when you elect a target you want. That way you get familiar with the process while able to see what you're doing so it's easier when you head out at night to play 🙂

Oh if you are running a mains adaptor outdoors, do keep it dry (pop it into a plastic box for example) and have an RCP on the mains supply line so you don't get any nasty shocks if it suddenly rains or condensation/dew get onto things.

 

 

[Paul_Sussex]

Don't know if it's any help, but on this page - https://www.meadeuk.com/Meade-StarNavigator-NG-102-Refractor.html - under Support there are guides and manuals for your telescope.

[AstroKeith]

That telescope doesnt use much power as it is powered by AA size batteries, so any regulated 1V supply of 2 amps or more will suffice.

It could well be bad contacts in the battery compartment. These pass enough current for the display to work, but as the motors kick in the bad contacts cause a big voltage drop.

Check the contacts, tabs and springs are nice and shiny clean. If a battery has leaked in there, use lemon juice on a cotton bud to clean it off. If using AA batteries - use Duracells or equivalent.

Clearly be careful connecting up an external supply as the Meade probably won't have bothered putting reverse voltage protection in. Sometimes is not obvious which battery contacts are the 'first' and 'last' - if it didn't power up at all, then I would double check this.