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Problem with CG5 (nonGTo) 6V handpaddle ?

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#1 Ian Robinson

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Posted 28 June 2009 - 12:20 PM

My old CG5 handpaddle (6V version that has telephone style cables going to the RA and Dec drives) will only track N hemisphere mode (irrespective of my switching it to S hemisphere mode and when I press the buttons to go at 2x , 4x and 8x in RA it will not select reverse direction speeds in RA.

I discovered the problem tonight .
I've not been using the mount since March last year .

I was powering it via my car's cigarette socket and a 12V-6V adapter.

Was testing my 300mm f2.8 lens and 40D when I discovered unexpected star trailing with 30 second test exposures despite the lens being mounted on the CG5 and my careful leveling and compass alignment with offset to the SCP.

I swapped the cables RA <--> DEC to test if it was the RA motor , the RA drive was able to be made go both directions as selected so I do not believe the RA motor is problem.

suggestions on a fix ?

#2 Ian Robinson

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Posted 20 July 2009 - 09:23 PM

Sent it off to Extravision in Queensland who had it for a couple of weeks and did some fiddling but couldn't "fix" the problem , despite my advising that I believed the RA drive wire (rj11 cable) looked damaged , must have dropped something on it.

Discovered one of the wires in the RA rj11 cable was indeed broken , so I did a dodgey quick fix (opened up a about 1" of the rj11 cable ,separeated the encased wires (4 of them) and trimmed off the damaged bit of wire , a quick solder a short of a length of wire to rejoin the broken wire and wrapped the wire bundle in insularing tape) and this seems to have fixed the problem of onlty one drive direction in my RA.
A now goes both ways at the press of a button. :) Can't believe it was too hard for Extravision's tech guy to fix the RA rj11 cable or replace it :foreheadslap:, or that thay missed it as the cause :shocked:.
Good thing that they charged me nothing to "look" at it eh.

Tested the "fixed" CG5 controller last night with my Sigma 50-150mm f2.8 APO and my Tamron 300mm f2.8 LD AD2all and tracking is not too flash (getting short star trails in 30second exposures .... may just have been my quick and nasty tripod leveling and my dodgey polar alignment and may just be drift ?? )

More testing is waranted .... need to establish if the RA tracking is at the right rate. Looks close , if it's correct then I'll seriously look at either :
- replacing the old CG5 drives and handpaddle with a EQ5 dual axis system (I believe these are clones of the original Celestron product)
- or push forward my addition of an Autoguider interface (by adding a rj12 interface and following the method suggested .... looks fairly straighforeward , I've taken the handpaddle apart it looks very similar inside), this way I may be able to zero out most the RA drive error and compensate for most of any drift due to less than spot on PA ???
<<<<< comments welcomed here , new to autoguiding >>>>

If the RA tracking is right (should be giving me one rotation of the RA wormwheel every 10mins (144:1 ratio) and I should get 15Deg rotation in 1 hr if 1x drive rate has the duty-cycle.

Forcast for another clear cloudless night tonight (3 nights with clouds in a row !!!) so I will set up the CG5 for another test with a better go at PA and something better than a quicky levelling of the mount

#3 Ian Robinson

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Posted 21 July 2009 - 08:49 AM


Tested 1x rate this avo , found it to be pretty close over a period of 2h 50m , calculated total angle = (2.833 x 360)/24 = 43.5deg RA , got via my magnetic lnclinometer (attached to the steel counterweight) 43.6deg RA.

So looks like RA 1x Southern rate is fine.

Dodgey PA and rough tripod leveling seems to have been the course of the trailing observed in 30s exposures.

Decided to resolder in a tidier manner the RA(S) wire , dammed fiddlely job even using a magnifying pantelevel lamp that my wifeosaurus used for her fiddlely craft work (on my big desk in my study.)

Next job is enhancement of the controller by adding a rj12 port permit autoguider interface.

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