Hi !
I built the Arduino DMX transmitter shield (http://www.arduino.cc/playground/Learning/DMX) with a SN75176B, then modified the code to send a 255 value to every channel, and loaded the code to the arduino, but I get mixed results. When I test the DMX signal with a battery operated MicroTech DMX tester, the signal is good, I can control every channel and the refresh rate is around 25Hz.
But if I connect the Arduino DMX output to any real DMX slave like Lightwave LX lamps, the lamp either doesn't light at all, or lights up for a few seconds then starts to blink very fast, and then shuts off.

I tried adding resistors to the DMX pins like in the Enttec Open DMX schematic, I tried fiddling with he timing of the arduino code. I tried a different 75176 chip and I'm not sure what to try next...

Do you have any idea of what I'm doing wrong?
Thanks a lot