Really a simple ( dumb) question I think ... I'm replacing batteries to an older Argo control model ( dark blue 102B ).
Before replacement of the AA batteries ... no display when switched ON.
After replacement of the AA batteries ... normal looking display & operation when switched ON.

As I get no BATTERY FLAT display I assume the 3V lithium battery still is good.
But, I want to replace the 3V as I do not know its age.

Reading the manual: I just open the hatch and replace it ( being careful of static issues ).
I assume the the controller ON/OFF switch is in the OFF position .... YES?

Or, should it be ON (to supply voltage) when the 3V lithium is out of the holder so I don't lose memory?

Brooks

Brooks,
When I replaced mine last month, the switch was off. Just be sure the metal clip is bent back enough to ensure the battery is snug to make adequate contact.
Al

Hi Brooks,

Thanks for the post.

I had replied to your direct email via a cell phone whilst I was on an observing trip to Mauna Kea but I will also follow-up here for completeness.

The job of the lithium coin cell is to provide power to the time of day clock in the absence of any other power source.

It does not supply power to the non-volatile memory where the SETUPS are stored and that memory will retain its contents even when no power source exists.

We recommend you power the unit OFF when replacing the coin cell.

Thanks ... got it done.

Very sad about your fires .... we spent time around Katoomba a few years back on vacation. Glad it was spared but can't imagine the destruction to that area