Gossen Luna Pro SBC - Powered but not measuring

Hello everyone, I was hoping someone could help me solve this apparent problem I'm having with my light meter
After purchasing the 9 volt battery and plugging it into the Gossen, all seemed perfect: the battery test button functioned as it should and the needle moved into the correct area. However, the measuring button itself doesn't seem to do anything, I press it and nothing happens. I even thought it might be a question of the Gossen being miscalibrated, so I cranked the ISO up to 6400 and pointed it directly at a light source, and even still nothing happened, the needle didn't even move.
Am I just doing something wrong or is there something wrong with the Gossen itself?
Thanks in advance!

Welcome to Apug!


My first guess is a broken wire in the metering circuit, as the metering switch seems fine as it still enabled the battery check.

But I do not remember ever having read here at Apug of a dead Profisix.

Does it have a flash mode? If so it might be in flash mode!

markbau said:

Does it have a flash mode? If so it might be in flash mode!

Click to expand...

That would make it a Luna Pro F - a different meter.
If it is a Luna Pro F, the switch needs to be pushed to the regular position, rather than the flash metering position to work normally with ambient light.

markbau said:

Does it have a flash mode? If so it might be in flash mode!

Click to expand...

MattKing said:

That would make it a Luna Pro F - a different meter.

Click to expand...

Good point, maybe the OP mixed up meters.

I did not think of this as the "regular" designations of the two meters are very different.
(US Importer Berkey caused all that confusion with their new designations.)

Just a hunch, but have you tried rotating the dial? Regardless of ISO setting, if the reading is off the scale because the dial is too far to one side or the other, the needle will not move. Hold the red button down and rotate the dial from side to side. Worth a try.

And, here's the manual:

https://www.butkus.org/chinon/flashes_meters/luna-pro_sbc/Luna-pro_sbc.pdf

And the film speed setting has no influence on the circuit, it is just a readjustung of the different dial parts against each other.