Synching two cameras with mixer audio

Si tienes un material completo de audio y por separado las tomas de apoyo, es muy dificial sincronizarlo manualemnte lo que debereas hacer es (como ya tienes sincronizado la camara 1) selecciona clip por clip de la camara 2  y con click derecho dale sincronizar.
Es lo que se me ocurre.
Saludos

first, make sure your sampling rate matches for the 3 sources and that both cameras were shot with the same frame rate (seems basic, but it doesn't always happen).   Although this may not be necessary, probably a good idea to convert so they all have matching sampling rates.   Back in the day, we needed genlocked cameras and seperate audio with a synch signal.  Now, I rarely have drifiting and I often edit events with this kind of configuration that last for as much as 90 minutes a take...   In terms of synching the 2 cameras (smrpix if one of the 2 camera is shooting intermittently I don't think Premiere will be able to synch them up, correct me if I'm wrong).  I'd then manually synch up the 2nd camera.  You might be able to run edit detection on the second camera and premiere may find all the edit points or not...  You'll find having a script a great help matching up the second camera.  I think you'll need to create a muticamera sequence with camera 1 and the mixer board audio and then open the multicamera sequence in the timeline (control click on the multicam sequence in the project/bin and choose open in timeline.  And then you can manually edit camera 2 into it...  It can seem complicated and not sure what your premiere skill level is....  so post back with any questions

Besides 'rate-stretch' you could also just resync at any point you need to. Besides the waveform, you can listen to the audio it will have an echo until they sync. (Let's say it can sync perfectly), in that case just move the audio track only (alt-left/right arrow) until the echo goes away and you are good to go. You can use the same technique down the line if you have drifting audio (likely).

Do it in two steps.

Since the cameras will synch together automatically do that.

Then add the board recording to another track and match it to the continuous-run camera manually usuing the waveforms as a visual guide.

If the board track is really a different length -- matching at the head but not the tail -- you'll have to use rate stretch on it to get it right.