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CPC 925 First Light - Disaster


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And so it arrived. I work at a school so I chose to get it delivered there. A friend had to help me load the two enormous boxes into my 5 door astra - it was a struggle. So I got it home and set it up, just looking at it was enough. It seemed to me the most professionally assembled piece of equipment that I have ever owned. Everything about it was professional, the finish the design and its appearance. So what I had cloudy skies - I also had flu so wasn't in the mood for stargazing at the moment. I thought reading the manual will do for now.

Then the worst November snow arrived, we had a few clear nights before that but we had always arranged to do something those nights so I was just looking for the next ideal opportunity to get going.

So December 5th here we are, clearish sky snow still around but path cleared and scope set up. Aligned the finder scope truned on and left for 45 mins to let the GPS get sorted. Coffee in hand I attempted a sky align. Find the three brightest stars in the sky and off we go - easy! Jupiter first, then Betelgeuse than another in the middle of the other two but not directly in line. ALIGN SUCCESSFUL the display read, excellent right lets try and find something.

Andromeda seemed like a good bet, so I selected it and off the scope went. To my utter dismay it ended up pointing towards the grass??? Now even I realised that looking through the eyepeice was not going to reveal anything. OK lets try something else, M16....again the floor. OK what about back to Jupiter....perfectly aligned but pointing at the floor.......I'm in the Northern Hemisphere Celestron!!!!!!!! The date is right the time is right, what on earth is going on. The only thing I can blame it on is the 12v adapter plug I bought from tesco to plug it into a mains cable that extends from the house. The temp was cold but I hear that this should present no problems. Has anybody had these problems before?

Oh and another thing, where does the barlow go, before the diagonal or after? and can anybody recommend a few eyepices for me, I have a 40mm celestron plossl that came with the scope but obviously need more. Thanks in advance.

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Have you checked the latitude and longitude?

The barlow goes after the diagonal - the eyepiece goes into the barlow.

EP choice depends on your budget, but orthos are usually rated well as good value for SCTs. I've recently invested in some Televue EPs and they are very good, but do some research to decide what will suit your viewing targets.

d

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Hi Anth, says in the manual if the scope has come from the southern hemisphere it may take more than an hour to link with the satellite, I guess though, you have bought it here in the uk. Power could definately be a candidate, a lot of times goto does have strange slewing issues due to it.

Alan

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I doubt it's the power supply/connection - from what you say, your scope is defiantely slewing which means it's receiving adequate power.

Possible causes (BTW - I used to have the Nexstar 6SE so the software's pretty much the same). As has been said by others, check your latitude and longitude settings are correct for your site. The defaults are somewhere in America I think. Check time zone - again the defaults presume you;re in America. I have no experience with GPS so I can;t help with how that works. I must admit that I don't use planets as one of the objects when aligning - I prefer to stick to stars - not sure if this may have a bearing on it.

Don't lose heart - I can remember having the pointing at the ground syndrome - it does happen and is usually because the scope is trying to find the object when it would be below the horizon whch would suggest the time/location settings are wrong. Don;t forget that Celestron in their wisdom have deemed that everyone should use the American date format - ie. MM/DD/YY - that has caught me out several times in the past.

As Tommy Cooper once said - "If at first you don;t succeedd - give up" lol:) Just joking - stick at it.

Regards

John

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I doubt it's the power supply/connection - from what you say, your scope is defiantely slewing which means it's receiving adequate power.
Ummm ... the connector at the scope end is a definite weakness with the CPC scopes. Intermittent connection scramvbles the computer memory, the scope may still slew but to strange positions.

Make sure the connection is properly made - it may help to very gently bend the centre pole on the mount. Tape the top of the connector cable to the fork arm (electrical tape works well) so that the connector is not stressed when the mount rotates.

....

Barlow before the diagonal is not reccomended. In fact with a long focus scope like a SCT, a barlow is not needed for visual work - and what isn't needed is best done without.

....

If you get an "align successful" with all sky align, use "undo" & check that the alignment targets agree with what you think they were. Planets are usually not good alignment targets because they move. I try to use Polaris, a bright star highish in the SE and another highish in the SW.

....

If your CPC has the same firmware as mine, immediately after aligning (& checking the alignment) go into "Scope Setup" and ensure that "cordwrap" is turned OFF ... the function does what it says!

Edited by brianb
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Sounds to me like you have it set in "EQ-South" mode. I've been caught out by this in the past. It'll send it straight to the grass as you say lol

Go into the "Mode" menu before aligning and choose "Alt Az" mode and you should be set right (assuming you don't have it on a wedge). Also - twenty mins is more than enough to get a lock on three satellites in the northern hemisphere. After an hour the scope will be cooled enough for good viewing.

Ep's - I find a Baader Hyperion Zoom works well in this SCT. Not as good as individual eye pieces but a big step up from the ep's found in ep sets, and a good range of click stops to complement your 40mm. Get the Mk2 second hand for around £95 - it's a great buy imho :D

(Edit - borrow a set of binoviewers and see what you think - it's awesome viewing)

Edited by brantuk
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twenty mins is more than enough to get a lock on three satellites in the northern hemisphere

Half a min is more usual, unless the scope has been transported a considerable distance since it was last used.

After an hour the scope will be cooled enough for good viewing.

Should be OK immediately with low power ... how long it takes to get to equilibrium is impossible to state, often the air is cooling as the evening wears on so the target is moving.

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Hi anth, I bought an 800 cpc aprox 7 weeks ago, but have only used it three times, now I bought it from 365 astronomy and they told me Celestron recommend you only use 12 volt battery power-not a transformer I was sent an e-mail detailing this from celestron.

Now I did have trouble 1st time but got it spot on 2nd time.

So hope this helps.

Cheers.

Edited by Martin Whitaker
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they told me Celestron recommend you only use 12 volt battery power-not a transformer

As long as the transformer supplies fully rectified DC 12V-14V and has a supply capacity of at least 3A you should be OK. The CPC has a substantial current draw especially when slewing.

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Ok thanks people, I will have to check that the EQ south mode is not on. I do have the date format correct and the time is correct (we are classed as universal time according to the manual - whatever happened to GMT i dont know) as for the lat and long how do you set that manually, I have the co-ordinates but dont seem to get an option from the menu system. Would anybody recommend buying a transformer pack for £70 it seems like an awful lot of money, is there not a cheaper option to power a CPC? Cheers, feeling a little more optimistic, and the skies are still clear at the moment......roll on 6pm

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The folks commenting on date, time format and so on can't be familiar with GPS scopes. That is the beauty of them, you just don't need to bother. You do have to set the mount mode though as Brantuk has said.

When I first got my Nexstar GPS scope a few years back it would go on a spin around whenever I started it. Eventually sorted with a new power tank which was kept as warm as possible. Power tanks don't work so well below freezing. Very small drops in power can affect the alignment before you notice a drop in slew speed. I guess it was a cold night when you were out. As Brian says, the connector is often a poor fit US/UK mismatch. On the NS8 you could poke a needle into the centre pin and this made things snug again.

Edited by MartinB
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So to follow on from Martin's point, what are the parameters that DO need to be set manually, if any? Recheck all of these. A poor power connection is a good starting point in other directions of trouble shooting though, and I would look there for sure.

I hate dependng on electronics (though in imaging I have to) because in terms of reliability they are at the level of cars in the 1920s. Or rather earlier...

Olly

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Are you sure you aimed it at the right stars when aligning? First time out, I screwed mine up so that it acted similar to your - it was because I hadn't aligned on the right stars. The right ones are really obvious, as they appear about 10x brighter than all the others in the viewfinder. I avoid using planets.

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Hmmm... interesting the different experiences people have had with CPC's. Aligment gives me no problem whichever objects I use. Once, I aligned on a rough center of the moon, Jupiter, and a more northerly star. I've also done it using 3 bright stars I don't even know the names of. Neither method let me down for visual use. :D

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This forum has not let me down, many thanks for the advice. I feel the problem lies within the power supply. After reading the replies and speaking to the very kowledgable guy at F1; only giving the scope 300ma (via a tesco adapter for £5 - supplying 300ma/ph at best) when it requires 7kma - it seems that I should be using a more reliable powew scource. Not having clear skies tonight i will try later with the car cigarette lighter which i'm led to believe suplies the correct ampage (>7amp/h ). Will let you guys/gals kmow. ttfn.

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