Aux returns out of phase with Channels

[Eric Blomquist]

Hello everyone.  Here is one more problem I have been living with for quite a long time, (I'm the only analog SSL open to the public in Minneapolis, so not a whole lot of tech resources up here).   My aux channels return to the board virtually completely out of phase with the originating channels.  So say, take Channel 29, engage the stereo and four mono aux's, patch the aux's back in Channel 30-35 line inputs, and Channels 30-35 are all out of phase with Channel 29.  This is the same for every channel on the board.  Anyone have ideas?

[kilmister]

Patchbay wiring perhaps? At least easy way to fix it is to mod patch wiring.

-Paavo

[michaeldtech]

Umbilical patchbay?  You could swap the DL pins in the corresponding points.  Kind of strange unless the board was heavily "improved" by someone smarter than those in Begbroke.
Did you check your returns as well?  Mult OSC into returns and channels and sum the same way.
Maybe check buses and everything.  Strange.
Mike

[unitedreco]

hi eric

what kind of console ....frame and modules, never ever assume you have a 100% all original console that hasnt had a mod done to it, if you do you are blessed....one of the big mods was the buss balance , alot of guys who had e frame when trying to drop in a g,g+ channel couldnt, the g+ especially if it had an afl mod made the channels and the board not act properly to an extent, phasing on aux being one of them, it only took 1 channel to take down a console....theres more detail than what im sayin but this is the jist of it.

[Eric Blomquist]

Thanks for the advice guys...after the holiday weekend, I will be back in the studio, and will run the recommended tests.

[Eric Blomquist]

Hey guys,  my console is an 4072 E with a G+ computer with Ultimation.  64 channels are E channels, 8 are G channels.  The board has definitely been modded over time, I'm just not sure how much.  The console was originally from Unique Studios in NYC.  It was originally a 56 channel board that was extended to 72, my best guess...in 1994.  The returns are in phase, busses are in phase...just the aux's are out.  Bizarre.

Eric

[michaeldtech]

Wow.  My young blood and sweat are all over that desk.  Literally.  I tech'ed there overnights on and off 88-93.  It had been kept so dirty for it's first four years of life and I was part of a fresh shop crew trying to improve standards. 

That was done in 90 IIRC.  G+ mods in 89 under the SSL radar.  They got the parts directly from Computer Associates.

I would go directly to the MRAC pinout because it was re-made longer to allow for the extra bucket.  You can de-pin MRAC pins with a cut straw as a slide tool.  Or you can fudge it at the patch bay.
50% chance that it remixed OPP, 50% chance it recorded Madonna/Lenny Justify My Love.
Mike

[Eric Blomquist]

Hey Mike,

Thats amazing you worked on the console!  I would love to hear more stories.  After Unique closed, the console was in storage for a good while...then it was down in Florida, then brought here to Minnesota where it was used for a year...then sat in storage for another 3.  I'm trying to bring it back to former glory.  Lots of recapping has been done...knock on wood, the computer is in great shape.  You have any helpful advice on the console you can remember?  The other issue I am trying to trouble shoot right now is that some channels lean hard when sent to the center section.  Oscillator into line 25, put channel fader at 0, and LF hits -1.7db quieter than RF.  Move the fader up and down...and there is a constant 1.7db difference.  I have recapped every card on the channel.  I have swapped faders...all to no avail.  Do you hav recommendations for me to trouble shoot next?

Eric

[michaeldtech]

If you have re-capped the output sections of the module, then I think that the cal pots should be lubed with a little F5, exercised, and re-set.  After so much time they have to be in need of some proper care.
Mike

[Eric Blomquist]

Alright, I massaged the module output pots.  I popped the module back into the console (the bank off, no hotswapping) and put the console oscillator into the channel.  LF and RF were .2db apart, perfectly acceptable.  I let the oscillator run through the channel for 10 minutes...at moderate level that wasn't stressing the channel...the levels stayed perfectly consistent. Next, I sent signal from pro tools to the channel, nothing too hot, hitting the channel right around 0....almost instantly, the channel goes back to the RF outputting 1.3db greater than the LF.  I then stopped audio from PT.  I put the console oscillator into the channel, and RF outputs 1.3db greater than the LF.  Oh boy, any ideas?

[Eric Blomquist]

Aha!  I massaged the balance pot on the output card, and that seems to be solving the problem.  Were these the pots you were recommending Mike?