rando@skipper.dfrf.nasa.gov (Randy Brumbaugh) (04/24/91)
I've received a lot of help on the net with light dimmer questions, and now I've got another . . . The theatre group I work with has standard 2 scene preset control boards with a 0-10 volt control signal output. The board is a TTI 12 channel model, if anyone should care. The board has a "dipless crossfader", like most. I understand what this does. My question is HOW does it do this? I took the cover off and saw a simple circuit board with several ICs and discrete transistors, so the circuit design was not obvious. Can anyone explain the principles or give an example circuit? Second (and a closely related question) recently the board started doing a sort of pulsing while fading from scene 1 to scene 2. It might be a neat disco effect, but really ruins a slow cross fade. This pulsing does not happen when fading using either the channel control fader or the grand master -- Only when using the XY cross fader. It happens even when fading to black using the cross fader as a split fader. It is a fairly old board. Has anyone seen these symptoms, or have any clue what the cause/fix might be? I suspect it would be easy to replace any of the components (assuming I could locate replacements). Also, I have tried switching dimmer packs and A/B switching with another similar control board. The problem is in the board, not the dimmers. Randy Brumbaugh rando@skipper.dfrf.nasa.gov