First let me update readers with myself. I have a Losmandy G11 base with an older Gemini 1 Level 4 version 1.05 computer and have been using it for several years quite successfully. The G11 is firmly attached to a Wheely Bar and I have a smooth even floor from the inside of my house out to the place where I observe from. I roll the setup out and screw down the 3 leg screws into permanent indentations in the concrete floor and have 2 precision levels salvaged from old theodolites mounted on the G11 so in short I can usually do warm starts every time I use my set up and only do cold starts if I have reconfigured the dovetail plates for a different telescope or have done anything else requiring cold starts. I use a STAR GPS normally for every start then uplug it once the SRAM has updated. Everything works very nicely and my objects are always very near centered in even medium powered eyepieces. About 2 months ago the GPS was no longer being read properly and I got the "GPS timed out" message. Working with Chris at STAR we narrowed it down to the cable and I ordered one from him. It hasn't arrived yet. Then about 2 weeks ago I got a CMOS rest message on start up. The last cell change was 15 months ago so this wasn't unusual. The cell was down to 0.2v so I changed it. Realizing that I now had no GPS and had swapped the cell I assumed that I needed to start back from zero, (My manual states this as well). That is I needed to put in everything manually like coordinates, time, mount type etc so I did this and then started building my model from a cold start. Strangely when I put in my selected star the mount slewed to a completely wrong position! (even though I have my CWD position precisely marked and always start successfully from there?). I assumed that I had simply made an error so started again being very careful. The same thing happened two more times. I was dumbfounded and had no idea what to do so put the set up away and tried again the next evening. Always the same!

I then tried something that made no sense but being desperate I decided to do it anyway. Even though my manuals say that going to the cold start option erases all previous models and even though I had changed the backup cell I decided to try a WARM START. The mount slewed to a location very close to where I had expected!!! Then with a low power eyepiece and in the "OBJECT SEARCH" mode I found the star very quickly! This astonished me but even so I was happy so I continued on and got 2 more model stars in the East and one in the West and built a good model. I observed for several hours more and everything went flawlessly???? That was 3 nights ago. My GPS cable is still in the mail so I cant test it yet but I will try again tonight in WARM START and see what happens.

Can anybody explain what has happened here? One of the club members asked me how long I had the bad cell out before putting in the new one. It was a quick swap but even still, the old cell read very close to zero volts using my FLUKE 189 DMM so I cant see how the pointing model could have remained intack in the SRAM. Also I cant understand why it would not do a cold start correctly. I have my Counter weight shaft down position very carefully marked for that "sweet spot" so that should not have had anything to do with it.

I will try again tonight if the Sahara dust permits. The other night the Sahara dust gave me some very stable views of Jupiter and Saturn so the dust can actually help as it tends to stabilize the atmosphere. (As long as its not TOO dense)

I will keep everybody informed. Please note that over the years usuing the Gemini 1 I have ocassionally had bizarre behaviour but it has always self cleared so I pay no attention. Maybe this is such a case but the SRAM retaining old pointing model data after a battery change out is strange indeed. A capacitor hold up? Who knows?

Thanks for any input and ideas
John Van Allen
Losmandy G11, Gemini 1 V4 Level 1.05, TV NP127, TV 85, Questar 7, Questar 3.5, AstroTec AT72ED with CG4 base for grab and Go
Santo Domingo, Dominican Republic? ?

Hi John you haven’t mentioned I fb you updated system location GMT offset and local time and mount parameters after a battery change. ? Gemini dtg is very different it’s:

yymm.dd: hh.mm.ss
See link here at bottom of the page ?

You may also find some hints on the Gemini

It’s quite odd for the battery to be “zero voltage” ? Is the new one you installed ok? ?What’s its voltage?

Also check that battery voltage is present at the SRAM by measuring it at the SRAM IC,

Also check your local time isn’t set to DST etc or is as supposed to. ? Most pointing errors are incorrect DTG or location positions. ?Google earth or a mobile phone can find your lay/long. ?

You can save your SRAM settings by using GEMINI ASCOM and re-import them after a battery change ? Look up Gemini ASCOM ! ?Makes it easy ?

Do get t back On these?

cheers

?

--
Brendan

开云体育

Is it possible the battery is upside down?