Gemini 1 - Hand Controller problem

[pmrid (Peter)]

For some reason, my Gemini 1 hand controller does not respond to direction controls using the RA/Dec arrow-keys. The main control box is connected by RS232 to a PC and does respond to commands sent from Gemini.Net using Maxim, but using the hand control for manual slews does not work. Anyone got any ideas?

Peter

[Marke (Mark)]

Does it have an internal battery ? if so could need replacing

[wasyoungonce (Brendan)]

Peter, does your Hand Controller (HC) display come up on boot?

Is the LED (below the menu) active?

Does the menu button work?

Did you try the "REV" buttons?

Have you just replaced the EPROM? I read somewhere that someone did this and they had to put to slew mode back to visual via RS232 for the system to restore...don't know why.

Is your cable to the HC ok?

You mentioned RS232. Gemini1's are particular about what or how much +5V is drawn from the system (PCB) and plugging in/out RS232, Auto-guider ports can shut-down the HC. Maybe remove them (all other devices) and try a re-boot. My Gemini BT was originally designed to use Gemini +5V but I found that sometimes plugging it in/out would cause the hand controller to go blank....aka a +5V line shut down.

Sorry lots of questions and you have probably already tried most...

Originally Posted by Marke

Does it have an internal battery ? if so could need replacing

..Nah..if backup batt dead you just get SRAM re-set on boot. The system will run with a dead Backup batt but lose settings and time when shut down.

Possibly a bad PTC Fuse F2...though more than likely a HC issue.

Brendan



A correction to the above and edit:

Gemini +5 volt regulator (U19) actually produces +5.4V and goes to 3 places. Two of these are thru Diodes D10 & D11 which drop this voltage to ~+5V and run the system ...aka CPU ect.

The +5.4V goes to the HC (pretty much by itself I think) and this feeds the HC thru J1 (DB15) +5.4V DC which powers the LED (I spoke above about, the HC LED) and display etc. The HC also gets +5V (from Gemini fuse F2) feed to it thru pin 1 of J1.

All this tells me if the LED (and probably display) are dead then you have lost +5.4V. If you have the display ok and the buttons do not work you have lost +5V via F2.

So try do the fault finding I mentioned with all points!.....and get back and I can make a rabid wayward assumption with no basis at all!

[cfranks (Charles)]

Is it the 'delux' version, with the LED display at the top. I have one of those (inc cable) for sale @ $110 posted if you find yours is faulty. New price is $285 + freight from Losmandy.

Charles

[pmrid (Peter)]

Originally Posted by wasyoungonce

Peter, does your Hand Controller (HC) display come up on boot?

Is the LED (below the menu) active?

Does the menu button work?

Did you try the "REV" buttons?

Have you just replaced the EPROM? I read somewhere that someone did this and they had to put to slew mode back to visual via RS232 for the system to restore...don't know why.

Is your cable to the HC ok?

You mentioned RS232. Gemini1's are particular about what or how much +5V is drawn from the system (PCB) and plugging in/out RS232, Auto-guider ports can shut-down the HC. Maybe remove them (all other devices) and try a re-boot. My Gemini BT was originally designed to use Gemini +5V but I found that sometimes plugging it in/out would cause the hand controller to go blank....aka a +5V line shut down.

G'day Brendan,
The HC functions normally in all other respects. The LED is operational,

All the boot process is normal, display normal, menu operation normal.

And the problem is present whether the RS232 is connected or not.

Haven't tried the REV button yet. Will give that a whirl. HC Cable looks fine.

I'm in the process of doing a full rebuild on that mount today and will be renewing all lings and connections. I'll report again after that.

Peter

[pmrid (Peter)]

Originally Posted by wasyoungonce

Have you just replaced the EPROM? I read somewhere that someone did this and they had to put to slew mode back to visual via RS232 for the system to restore...don't know why.

I omitted to answer this question. Brendan, this is the Gemini you repaired a few months back but it was the main control box you fixed. You didn't have the HC at all.

Peter

[wasyoungonce (Brendan)]

Originally Posted by pmrid

I omitted to answer this question. Brendan, this is the Gemini you repaired a few months back but it was the main control box you fixed. You didn't have the HC at all.

Peter

Yep ran it with my HC.

I have a HC diagram. So far:
Pretty much is 5.4V is present, the LED is on.
If the +5V was not present (pin 1, J1)then the display IC's would not be buffered with data (from the controller), it would lock up or disappear.
The keypad has a PIC micro controller that reads key presses and this uses +5V as well.

All in all looks like a bad HC cable or +5V is not going to all the appropriate places in the HC. My bet is cable. If the membrane was bad then some buttons would work and some not.

[pmrid (Peter)]

Originally Posted by wasyoungonce

Yep ran it with my HC.

I have a HC diagram. So far:
Pretty much is 5.4V is present, the LED is on.
If the +5V was not present (pin 1, J1)then the display IC's would not be buffered with data (from the controller), it would lock up or disappear.
The keypad has a PIC micro controller that reads key presses and this uses +5V as well.

All in all looks like a bad HC cable or +5V is not going to all the appropriate places in the HC. My bet is cable. If the membrane was bad then some buttons would work and some not.

I just did the strip and rebuild thing with no improvement. Next step is the cable to the HC. But a quick question about that - is that a standard RS232 cable or some sort of cross-over variant?

[wasyoungonce (Brendan)]

The cable is straight thru no crossover.

[pmrid (Peter)]

Originally Posted by wasyoungonce

The cable is straight thru no crossover.

Thanks Brendan.
It's turned to soup up here today and forecast for the weekend is wet, wet, wet. So I'll have a play with it in the morning and report back.
cheers
Peter

[pmrid (Peter)]

Originally Posted by wasyoungonce

The cable is straight thru no crossover.

Looks like this will have to wait until the next camel train to the city passes by. The only serial cables I have are the small type, 9-pin instead of the big ole'ones that are on the HC/G1.

Always some flamin' thing isn't it.
Peter

[wasyoungonce (Brendan)]

Peter you can pin to pin measure the resistance of each internal wire with a multimeter, best on low ohm's or if you meter has a low ohm's buzzer.

If your probes are not small enough you just wind a thin'ish wire piece around each to fit the pins.

Try flexing the cable near the connectors or along it's length to check the each cable internally isn't broken.

[pmrid (Peter)]

Hi Brendan,
interesting development - possibly unrelated symptoms but:

1. I found that by doing the ''hold-one-side-and-doubleclick-the-other trick' did work in getting the mount to move.

2. Now it won't guide. It is not acting on guide signals whereas it was guiding fine the very night before I tried the double-click trick mentioned above.

I'm going to have a look at that battery and see what the levels are. Is that a possible source of the problem do you think?

Peter

[wasyoungonce (Brendan)]

This is all very odd. Is the mount in visual mode?...won't guide in visual.

Battery is only there for +3V "backup" for SRAM and RTC. Once +12V applied, the PCB makes +5V (actually +5.4V) and this then supplies the system and SRAM & RTC via steering diodes.

So you can take the battery out when powered on. Or power on without it...you will have just lost time and SRAM data. Which will be lost again if shut-down with no battery inserted.

Still...I am confused by symptoms and goings on...they are all over the place. Moisture in the hand controller flex? Is the EPROM seated ok?

[pmrid (Peter)]

Ahhh blow: You will be familiar with the diagnostic technique that says before you open the case, examine everything between the seat and the keyboard. Well, it's good advice. I had the HC in All-Speed-Mode but whenever I connected via Gemini.Net, those settings overrode the HC and, of course, there it was inside the Gemini.Net settings - Visual Mode.

Sometimes it's difficult to resist the temptation to curse!!

Peter

[wasyoungonce (Brendan)]

Ahhh so it's all good?

[pmrid (Peter)]

Originally Posted by wasyoungonce

Ahhh so it's all good?

Still won't guide. Dammit!! AND NO CLUE WHY. Tonight I'll try a new RJ12 cable and see what happens.
P.