Hi, I am attempting to add a PFL mod to my original Mackie MS1202 mixer. A forum member graciously posted this schematic (from the original Manual) and I am re-posting it here for reference:
http://www.twin-x.com/groupdiy/albums/userpics/Mackie_MS1202.zip
I also attached just the Schematic portion that contains the Headphones section and Master section. The resistors I lifted (R29 and R30) are just below the very center of the page.
My goal is to be able to Cue any one of the (4) stereo input channels through the Phones. The signal should be pre-fader. I only need to be able to Cue one stereo channel at a time.
I have a nice little Grayhill 5-position stereo rotary switch that I'm going to mount to the front surface of the Mixer once I've got the basic principle worked out (the four channels, and headphone mute, will be the possible switch settings.) Here is what I have done so far:
1) Disable original Headphones output. I did this by lifting resistors R29 and R30. (This can be seen on "pt4" of the schematic.) This was successful; I am not getting anything out of the headphones now.
2) Just as a proof of concept, I ran a wire directly from the Tip input of a channel, to "just after" R30 and I ran a signal through that channel. The master meter is lighting up (so I know I'm getting signal), but even if I turn the Phones knob up all the way, I hear the input only extremely faintly and distorted.
I have a feeling that I need to do something simple (grounding something to something else?) but I'm a little embarrassed to admit I don't know what. So, any hints or things to try would be much appreciated!
rs
ps - I know I could get something that already does what I want for cheap. But this is largely for the learning experience. 8)
http://www.twin-x.com/groupdiy/albums/userpics/Mackie_MS1202.zip
I also attached just the Schematic portion that contains the Headphones section and Master section. The resistors I lifted (R29 and R30) are just below the very center of the page.
My goal is to be able to Cue any one of the (4) stereo input channels through the Phones. The signal should be pre-fader. I only need to be able to Cue one stereo channel at a time.
I have a nice little Grayhill 5-position stereo rotary switch that I'm going to mount to the front surface of the Mixer once I've got the basic principle worked out (the four channels, and headphone mute, will be the possible switch settings.) Here is what I have done so far:
1) Disable original Headphones output. I did this by lifting resistors R29 and R30. (This can be seen on "pt4" of the schematic.) This was successful; I am not getting anything out of the headphones now.
2) Just as a proof of concept, I ran a wire directly from the Tip input of a channel, to "just after" R30 and I ran a signal through that channel. The master meter is lighting up (so I know I'm getting signal), but even if I turn the Phones knob up all the way, I hear the input only extremely faintly and distorted.
I have a feeling that I need to do something simple (grounding something to something else?) but I'm a little embarrassed to admit I don't know what. So, any hints or things to try would be much appreciated!
rs
ps - I know I could get something that already does what I want for cheap. But this is largely for the learning experience. 8)
