I have one fully functioning 4 gas analyzer SGA-9000, almost in like new condition with very little use.
When I got it, it was dead.
Then I bought another one and used it as a parts donor.
It was the opposite, totally used up and bad and also dead, so I just removed the parts I wanted and the case went in to the dumpster. Out of the two, I do got the first one going and it works like new, including the chemical O2 Sensor.
The SGA-9000 only has serial communication, no CAN bus in this old one.
If your only has the one chamber, then it is detecting the different absorption rates of the different wavelength in one single chamber. This was probably not possible at the time, they built the older model.
Hmmm your picture looks like it is the transmitter, based on the heat sink?
I am not sure.
The transmitter should be located across from it of the other side of the tube.
Usually only the transmitter broke. They have a lifespan like a light bulb and moving the analyzer around, while it was turned on, reduced the life span of the transmitter.
I have no idea about the password.
The SGA-9000 has 3 potentiometers for each gas to set the zero, the max and the span.
A complete calibration process of the SGA-9000 takes about 1 hour with different test gases.
I just love the quality of these machined aluminum parts for the bench.
No wonder, the price was over $ 10.000 for the base 2 gas unit in those days.