I've put one of these together for a client and I'm trying to calibrate. Is there a procedure for calibration using a standard function generator?
Preferably one that I can count LEDs to align with as I don't have the purpose made JLM meter scale.
Also, I'm not understanding how to jumper the unit so the LEDs are in full brightness mode all the time. I can apply a jumper to position 1 and get the 2.5V dimming or I can remove it and I get the dim then brighter with level behavior.
For full brightness fit jumper in header which will link pin to 0v for full brightness.
Put in 1khz tone and turn input trimpot RV1 up until you have just lit the 40th red led. Then turn up VUPPM balance trimpot RV2 until the 40th green led just lights. Cal between VU and PPM is not done. Adjust input trimpot to maximum input level for your system.