ARGUS MD 222 A - help with battery solution

[ivconic]

You are telling me, that blue wire (see attachment, and on real unit also blue wire from battery) is not neccessary here?

Is that might cause "sound problem - constant sound after long using" mentioned by previous owner, if say, one of battery go below 5v6, and other stay 9v?

In regardless to Patrick shematic, without blue wire (battery central tap - 0V), its seems that unit will work ok, unless he reach 11.2V on source. Why blue wire exsist originaly from manufactured, if offfer only unstabillity and lower performance?

Sorry! I missed that!
That blue wire should be there, of course, it is central tap and connected to common ground.
But if you use single battery and generate from it symmetrical voltages; than it is redundant.
And your understanding is correct, if one battery goes down too soon ; it will affect detectors behavior.
Detector needs symmetrical power supply. Obviously +/-5V at rails.
Any of given solution should do.

[Harp]

In case of two wire option, what is the difference and how circuit know, is there +9V (red) and -9V (black), or 0V(black) and +18V(red), or 0V(red) and -18V(black)?

The circuit in schematic seems almost identically like Fig3 (symmetrical with zenner) and transistor schematic as I posted previous here https://tangentsoft.net/elec/bitmaps...ds/sijosae.png
I'll not understand what is purpose of third (blue 0V) wire, and is it necessary to create just one more (functionally identical) circuit that make symmetrical rail, if its present jet in a originally board?

[Harp]

And here we are! Are you still here?
I'm sorry for gap, that is life.
I was cleaned pcb with alcohol from flux, contact spray pots, it is shiny now, reasembled device, and it work.
I am not familiar with IB, so a ask a little help, what is what and how to setup.
I guess the first pot (lower, with on/off switch) is sensivity, the upper one is discrimination. What do two switch near the shaft and when to use it? I see that switch affected to both pots settings.
Have anyone a discrimination map for this device? Or even better user manual? How to use analog meter, which information I can read from it?

As you can see I dont know how to setup device for testing, so the results not become relevant.
Some photo in attach.

[bernte_one]

welcome back

[Harp]

I am done with air test video

https://www109.zippyshare.com/v/3SZgsv4T/file.html

or

https://www109.zippyshare.com/d/3SZg.../argus%201.mp4

Argus 1.mp4
16MB

Please somebody who have yt to copy this video and paste link here, otherwise he can stay on zippyshare only one month.