Advice sought for wobble and power issues - Nexstar

[stevil]

Hi,

I got my telescope out yesterday, the first time I've had an opportunity at night as I've previously only been looking at the sun through a filter. The sky was quite light (I stopped observing just after midnight) so only looked for a few stars and the moon using my new BST Explorer eyepieces.

One thing I have noticed is that the telescope really shakes, can anyone advise me on how to resolve this?

Also I was getting quite frustrated as the power tank cable kept on falling out of the mount when I was moving the telescope so I would have to start again.

On the positive side I found the red dot finder OK to use and I was quite taken back by the moon. The wife was also really impressed, more so than the white light solar observing earlier in the day!

The telescope is a Celestron Nexstar 127.

Thanks

Steve

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[Greg48(newbe)]

I've mostly asked quiestions and never answered but put some batteries in so

you save all the info you entered and what i do is make sure there's enough

slack on the cable when the scope is turning it won't get caught aroundf the legs

of the tripod,,HTH,,,i've heard of vibration pads to stop some movement in it,,,

would you be by any chance having your scope on decking,,that would cause

movement because it happens to me sometimes when i move about when

looking thru the EP

Greg

[gkec]

A weight on or hanging from the eyepiece tray may help with the wobble.

[knobby]

Try not extending the tripod legs fully, try some extra weight hanging from the e.p. tray, when you've set up push the tripod legs out from the centre to sit them nicely... Also make sure all the screws / nuts are tight (don't break them though).

If you can keep a set of batteries in as well as the power adaptor then it should keep the settings.

check the menu settings for 'cord wrap' it stops the mount from turning all the way round.

If you really want to try something whacky... Camping shops or fishing shops sell screw in ground pegs. You can screw one in the ground below the scope then use a bungy tie from the e.p. tray to the ground peg

Good luck and have fun tweaking!

[stevil]

Thanks, will have a go at the tripod and try the batteries as well.

Cheers

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[breezy]

Drat all suggestions I had have been suggested

[M4lcs67]

I have this scope and have mods for the questions you have asked. I wrap the powertank cable around the mount a couple of times to stop it from falling out. Also make sure you keep the tank topped up and never ever let the thing run down otherwise you will wreck the cells in it.

With regards to the wobble, place a bag of sand on the ep tray. That normally cures it.

[stevil]

Thanks I will try wrapping it around too.

Do you mind if I ask how long the power tanks lasts if it is not being used for a while. I read somewhere you should charge it fairly frequently even if its not being used.

I work away from home for 5 weeks at a time so I was hoping that as long as it was fully charged when I left home, the battery wouldn't degrade too much by the time I get back, maybe give it a little boost charge?

Actually I say power tank, its actually a Maplin jump starter!

Thanks

Steve

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[jonathan]

Yes, charge during the day before you use it if possible, then it will be fresh. Try not to discharge beyond 50%, so a few calculations regarding your typical power drain and the battery capacity should give you your ideal running time before it needs to be recharged. Those starter batteries are designed to be constantly topped up, if you want one that can be drained fully so that you get a much longer running time then look at a leisure battery, even a small one should give you several hours of mount rotation and dew tapes if you use those.

[breezy]

Steve I have a maplin power starter, been used for a year now and tbh gets charged only when I think about it, over the last two weeks it's been well used , seems to last a good few hours before needing a top up. Maybe I'm lucky with it but its OK so far.

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[baggywrinkle]

A weight on or hanging from the eyepiece tray may help with the wobble.

Put the weight in the tray, do not hang it. Any movement will set it off in a pendulum motion. I have an iOptron mount which is light and use a divers belt weight in the tray.

[stevil]

That's great, exactly the advice I was after.

Thanks guys.

[Lonestar70]

Hi Guys,

A word of caution regarding rechargable power tanks.

Those starter batteries are designed to be constantly topped up, if you want one that can be drained fully so that you get a much longer running time then look at a leisure battery, even a small one should give you several hours of mount rotation and dew tapes if you use those

Skywatcher and Celestron mounts will start playing up, or even stop working, when your battery voltage drops below 11v... although items such as dew heater bands will still work (but at a reduced power).

Whilst it is true that a leisure battery will hold up for longer, you cannot drain it fully... this will damage the cells.

The minimum recommended voltage per cell (6 per battery) is 1.3v for a leisure battery... giving a discharged battery voltage of 7.8V.

For a standard power tank you should charge it when the output voltage drops to 9v.

Never leave either type in a discharged state as this will lead to irreversible plate damage.

A fully charged battery will self discharge over time and should always be recharged fully before re-using it.

A period of 5 weeks storage should not be a problem for either type if it is stored in a dry, cool location.

Keep happy.

Best regards.

[M4lcs67]

My powertank has finally died after two years and I needed a more reliable source of power to drive my CG5, so I bought a Maplin 12v mains power supply which I plug into our outdoor socket.

My observing place in our garden is only 20 feet away from the socket, so that has cured that little problem.

[stevil]

Thanks, if it gives up the ghost that could be a good alternative as my observing site is quite close to the house.

Cheers

Steve

[M4lcs67]

I had the Maplin 3 in 1 jumpstarter myself. it worked well with my 127 SLT, but once I got my CG5 it couldn't cope anymore, so I got the mains supply. A more direct, constant source of power and there is no chance that the power will run down anymore as it is connected to the mains.