Product review (1 stars): Disrupted Machine's Settings Cycles
Yep, it didn't work on my Respironics System One, either.  It kept making the settings cycle out of sequence, and I couldn't breathe with it.  It's difficult finding power packs that work for these machines.  Ironic that Phillips spends all this money to perfect the machine, then can't offer a readily-available OEM power supply to make it work.