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Gemini 1 Level 1 System Not Powering On

 

I am working with the Takahashi FSQ-106 refractor and operating it with the Losmandy Gemini 1 Level 1 computer system along with the Losmandy GM8 mount.

I am running into an issue where the system does not power on or display any messages on the LED display even when it is connected to power. So far, we have tried replacing the CR2032 lithium battery, but this did not resolve the problem.

Was wondering if anyone has experienced this before and/or has any troubleshooting suggestions?
 

I suspect that it is an issue of voltage. You must provide at least 15 volts. Gemini loves 15 volts :-)
 

A fuse that might be at fault:

 

Depending upon your version type of PCB ).?? Below is an image of D10 on a Gemini 1 ver 2 pcb and ver 1 PCB..

Version 1 and some version 2's have diode D10 (dual common anode, in a SOT23-3 package), which is prone to "blowing" (usually caused by someone doing something, but they do run close to their tolerance) which will cut 5V to HC and many other Gemini ICs (depends upon how it "blows").??? You mentioned you have CR2032 thus there is a possibility you have one of these Gemini's.??? Later version Gemini 2s and ver 3 Gemini 1s didn't have this diode and instead had D10/D11, typical SMA diodes.

As Paul stated, Fuse F2 is the most common cause of the HC going blank see attached image.? Usually its marked "X14" but it might have other markings,

Any of these can cause HC and other Gemini issues.?? Get back on the Gemini version you have and if you are handy with a multimeter i can tell you where to probe to measure.?? If you have a bad "X14" you can jumper it with tweezers...if that gets the system working, you need to replace this fuse.? Get back we can advise on this

cheers






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Brendan
 

Response to 15 volts. I recently bought an GM8 and running it off a hardy garden tractor battery. Even though everything is working well, I'm probably missing something. Would I find value by adding a boost transformer to gain 15 -18 VDC? As luck would have it, I pulled the board out of my Kindrick power supply years ago to make room for a greater range of output plug sizes. All at 12vdc. Silly me. Thanks for Your Time!
 

The system runs fine on 12V DC. ?I ran my own on a computer PSU 12V out for two years. ?


To many obsess about the need for a higher voltage! But basic forces in a motor f=¡°sintheta BIL¡± where ¡°B¡± is magnetic flux density, ¡°I¡± is current and ¡°L¡± is length or motor wire conductor. ?

Using ohms law V/(IR) so ¡°I¡± (current) is increased if ¡°V¡± voltage is increased. ?


This is why a motor runs a little bit better with a slightly higher voltage ¡­.it¡¯s because it¡¯s slightly higher current. ?


But as said it is designed and ¡°will¡± run fine at 12V DC . ?Don¡¯t obsess over higher voltage. ?If I had an observatory ?then I¡¯d think about getting a 15-18V PSU. ?But 12V is universal for all accessories.


Oh, do I now use 12V DC? No, I mainly use 15/18VDC as I repair Geminis and it¡¯s easier for me to use this as output from my programmed Linear power supplies. ?I can compare current draw between units using same input parameters

FWIW
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Brendan
 

Brendan,

I respect the handson experience of seasoned users. Additionally, I would have had to craft a new socket so I wouldn't risk plugging a 12 volt GoTo into an 18 volt socket. I'd rather have a counter weight drop on my toe. And, I just made a new cable with a nifty 90 degree DIN plug. If memory serves, I have you to thank for that part number.

Bottom line, keep it simply. Why change it if it's working well?

1,000 Thanks,
Ernie?

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