Turns out this was not the manual i was looking for. The concertmate 670 keyboard i have is a "Realistic" model made for Radio Shack and none of the diagrams on the owners manual i received matches up. HOWEVER, I must say the service Owners Manual provides was fast and efficient by being available online. The manual was in good readable condition and easily downloaded.
Thank´s for your help, I already recived these manual from you
Text excerpt from page 3 (click to view)
Owner�s Manual
killing ground lift switch that (unlike other acoustic preamp/DI's) works even when phantom power is applied to the preamp.
QUICK START
1. If you are using the XLR output, set the Pre / Post switch to "Post" position. 2. Adjust the Input gain so that the Clip/Low Battery light barely flashes with strong strumming. 3. Strum hard and raise the Smooth knob up until you hear the Compressor take the percussive edge off your highs. 4. Phase: Flip the Phase switch to the position that sounds best and suppresses mid-bass feedback 5. Notch: To squelch deep bass feedback, adjust the Notch dial between 1:00 and 2:30. The Notch is off in the 7:00 position.