Hi Chris!
I've already managed to get the PFL/AFL working, it was disabled on the monitor module. I've found 2 traces cut on the board and 1 pull down resistor on the enable trace to keep the pfl monitoring from switching up. Removed it, restored interrupted traces and everything works as it should.
Also I've reversed the blocks around the trimmers and found what they set.
VR8, VR9: set the post pan\width unity gain.
VR12, VR13: set the post fader global gain. I've adjusted them to have the same level between PFL and AFL with fader fully open.
VR10, VR11: trim the symmetry on the dbx 2150 vca, I've adjusted them to trim away all the 2nd harmonic.
VR14: it looks to inject a CV on the negative control ports of both 2150 vca, can't figure out why it is needed so I've left it untouched. Any input here is welcome, just for the sake of learn things
Of course trimming is done after recap!
No circuit diagrams I'm afraid but PFL is normally straight forward as an an output.
just follow the pfl button to the edge connector on a channel and then look at the master modules to see which one takes the pfl bus up onto it to an opamp input and then off the an output...
On the channel the switch may control a 4053 to switch the audio (a popular Calrec design) but just follow the logic to the IC read the datasheet for the pinout and switch then look at the pins it goes to on the 41612 connector.
Don't twiddle pre-sets unless there is a specific thing to adjust. Replace all the electrolytic caps first then measure it. Twiddling presents before replacing caps and testing everything normally causes issues. the number of "repairs that I have seen from people maxing out pre-sets is TO HIGH. haha measure first, repair, measure again.
April 09, 2005, 08:03:44 AM