388 Aux Buss Not Working

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Mark7

Mark7

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Not sure if it's something obvious that I'm missing. Tried both the 1/4" and RCA jacks, Aux Master at 100%, Aux Send on channel at 100%, Nada.
 
And you can’t get anything to work from any of the 8 input channels? And the PRE/POST switch is in the unlatched/up/PRE position (or it’s in POST and the channel fader is raised)?
 
The channel fader is raised and it's the same thing on channels 1 and 4 and with the switch in either position. I'm not going to try out every channel individually.
 
I would, in order to verify it is a global issue likely at the summing stage. That’s my advice.
 
Tried 7 of the 8 inputs (the 8th channel is being used as a mono effects return for printing delay to vocal tracks). All pre/post switches in the pre mode but all faders at unity gain. Channel aux sends and master controls at maximum. Nothing. I can't believe all 7 (or 8, since, what's the use of an aux buss that only works with one channel) aux sends are faulty so it must be something to do with the aux buss. Or I'm missing something in my set up. Which is...

Aux send to patch bay out (tried the aux send in a different out jack, same result)
Mic/instrument via aux send control on mixer channel to aux buss
Aux buss to delay via aux master
Delay out to patch bay in
Patch bay In to channel 8 mic in.

I suspect the signal isn't getting to the aux master. Confirmed this by switching monitoring to aux/eff aux only. No signal
 
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I had a look in the service section of the manual and I've realised there is no aux buss pcb card. So chances are it's either a faulty aux out jack, or the signal isn't getting from the aux send controls to the aux master control, or it's not getting from the aux master control to the aux out jack. Which means the aux out is faulty.
 
There’s not a dedicated PCB for each buss. The AUX and EFF summing and output amps are on the BUSS A or BUSS B PCB. The signals get there from the input channels via the BUSS PCB. I’d start by verifying the signal is getting from the BUSS PCB to the PCB with the summing amps.

It’s not a bad jack. If that was the case you’d still be able to hear signal when you select AUX/EFF as your monitor source, and see activity on the meter.

[EDIT]

Okay...memory refreshed. The AUX and EFF buss summing and output booster amps (U101 and U201) are on the MONITOR PCB.

What happens if you connect a source to the EFF IN or AUX IN jack? Can you hear that source when you select AUX/EFF in the monitor section?
 
Not at all, and I tried it with the Aux/Eff|L/R monitor switch in both positions in case it had been mislabelled. Neither the Effect nor the Aux Out jacks produced any sound or meter response when I ran my drum machine through them. Which is odd, because I know the effect send works.

For the record.

I plugged the mono output of the drum machine straight in to the Effect Out Jack
I set the Aux/Eff|L/R switch in the monitor section to Aux/Eff
I switched the monitor source in the tape section to Effect

Nothing (and yes, the drum machine was playing and, no it wasn't an empty pattern)

Then I did the same but with the drum machine plugged into the Aux Out jack and Aux selected as the monitor source. Again... Nothing.

I wonder if that might be because, as outputs, they're expecting an internal source?
 
Did you mean the aux and effect buss in jacks, beneath the effect return jacks? I never use those. I only ever use the aux/effect out back to effect return or stereo buss in loops.
 
Just to be clear, I've also tried it with the RCA jack. That doesn't seem to be emitting either but the RCA for the Effect out is,
 
Mark7 said:
Not at all, and I tried it with the Aux/Eff|L/R monitor switch in both positions in case it had been mislabelled. Neither the Effect nor the Aux Out jacks produced any sound or meter response when I ran my drum machine through them. Which is odd, because I know the effect send works.

For the record.

I plugged the mono output of the drum machine straight in to the Effect Out Jack
I set the Aux/Eff|L/R switch in the monitor section to Aux/Eff
I switched the monitor source in the tape section to Effect

Nothing (and yes, the drum machine was playing and, no it wasn't an empty pattern)

Then I did the same but with the drum machine plugged into the Aux Out jack and Aux selected as the monitor source. Again... Nothing.

I wonder if that might be because, as outputs, they're expecting an internal source?
Click to expand...

You’re connecting the output of the drum machine to the AUX OUT or EFF OUT on the 388? For sure that will never work. You can’t connect two outputs together and expect signal to pass.

Yes, when I suggested connecting a source to the EFF BUSS IN or AUX BUSS IN jacks that’s what I meant for you to do. That injects signal directly to those summing amps, bypassing the connector board from the input channel strips. We’re trying to narrow down where the trouble point may be.
 
Okay, so I tried that. First I connected the mono output of my drum machine to the Aux Buss In jack, switched the monitor select to Aux/Eff, switched monitor source to Aux and increased the level of the Aux Master control whilst the drum machine played a pattern. Only at its maximum limit of travel was I able to hear even the faintest sound.

Then, I switched to the Effect Buss In jack and changed the monitor source as required, This time the sound was good and strong even at a low volume.
 
But you can’t get signal from the input strips to the EFF buss? It only works if you inject signal at the EFF BUSS IN jack?

And with the AUX buss, is there a way you can hit the signal hard at the AUX BUSS IN jack and tell me if on transient peaks you get signal to pass but just on the peak and if so if it’s all crunchy? Like a hot kick drum from your drum machine and you get the kick to come through but only just for a tiny bit of time with each kick, like it’s tightly gated but it’s crunchy what you can hear? Or is it still no matter what you can just barely hear it?
 
You mean from the input strips to the Aux buss. Since that's the one I'm having the problem with.

Okay, this is weird. I tried sending the drum machine through the Aux buss in again and this time I am getting a good strong signal.
 
I checked on both jacks, because I can't see which is which, and they both gave good strong audible signals
 
No. I actually wanted you to confirm for me you could not get signals from the input channels to the EFF buss...I already know you have trouble with the AUX buss. Trust that when I ask you something it is what I want to know in order to try and help you. I proof read my posts.
 
Yes, I've been using the effect buss to add reverb and echo to my vocal whilst I've been tracking.
 
Yes, I've been using the effect buss to add reverb and echo to my vocal whilst I've been tracking.
 
And when I say, adding reverb and echo to the vocal, I mean printing it to the track (because without a second effects send I can't do it later).
 
Okay. Understood.

So since you’re getting signal at the AUX OUT jack when you have a source connected to the AUX BUSS IN jack, that tells me it’s not a problem with the AUX buss summing and output amp section on the MONITOR PCB. The first place I would look is to inspect the solder joints and connections where the M BUSS PCB (the long strip of PCB that spans across all of the mixer boards) connects to the MONITOR PCB.
 
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