Can you determine RGB pinouts with a multi meter?
Some multimeters have a diode tester so you could use that on any number of LEDs to find their forward voltage. This may not work on adressable LEDs. Other than this you can try to identify the LEDs and Google them to find the spec sheets Fv at the least, but bear in mind that this is usually fairly inaccurate but it could be your only option.

You could also check the output of the PSU for the LEDs and go from there about a correct supply voltage.

If I needed to test the pinout I would:


Try to find a schematic in the manual
Tap each contact with a lesser supply voltage till you get lights
Attempt to find the schematic and specs of the IC that is being used to make the LEDs adressable throughout the strip. This might also reveal the reccomended input as I would hope the ICs had a constant current driver (better running conditions for an LED than contant voltage).


Hopefully this is what your looking for!