SSL 4000 E 16khz noise on output quad buss aux

[CarloColugnati]

Hello everybody !
I'm Carlo , new to this forum.
I've really appreciated reading some of the posts in here ,thank you guys to share your knowledge !
Hope to do the same with what i know about this fantastic machines.

Now let's skip to the big fun !

I'm working on a SSL 4000E with G+ series EQ's/computer.
I have a problem with a fixed noise 16khz@-40db on the desk output (the whole patch raw)  and auxes.
I've tried several things like :

1)swapping front with rear mix cards
2)recapping cards
3)unplugging everything in the room

do you guys have any suggestion for me ?

[waltzingbear]

unplug the osc card in the center section, is the tone still there?

Alan

[CarloColugnati]

Hello Alan !

I've unplugged the oscillator card (82E34) and i still have the noise !

[waltzingbear]

a tone at that level sounds like its leaking from somewhere. You need to find where it is strongest. A circuit oscillating would be at +20dbV, not -40. Check all the channels at the direct outs and inserts. Still not found? Remove the channels, still there?

In other words eliminate sections and locate where it comes from. Then you can make progress on eliminating it.

look at the power supply rails with a scope, is the tone there?

Alan

[CarloColugnati]

I've checked the PSU and there is no noise on it .

I've found this tone on the insert send of channels 5-10-13-15 , and also on the group outputs bar from 1 to 32

Now i will switch off the buckets and remove incriminated channels and take a look.

Thanks again for support !

[CarloColugnati]

ok i've switched off the buckets with incriminated channels , the noise is the same , and appeared on other channels ....

this sounds like a stupid issue but hard to find ....

[Matt Sartori]

it sounds like a wifi router to me...
check where they are and switch them all off...


Matt

[Chris Simon]

Is it possible the noise is related to the onboard CRT for the computer? What happens if you turn the computer off?

Chris

[CarloColugnati]

turned the wifi off the noise have not been affected.

the automation/recall computer is already switched off for maintenance , broken reel disk reader .

you guys know if the screen sound floppy reader is compatible with the reel disk reader , looks like it's the same but with different jumper positions.

don't know maybe i have to start a new topic about disk reader...

[waltzingbear]

I believe he meant turn off the VDU in the center section when referring to turning off the computer, the horizontal flyback is around 16khz, could be leakage.

Alan

[Chris Simon]

Yes, that's what I meant, thanks. The VDU is powered by the computer power supply in the rack, isn't it?

[CarloColugnati]

Yup it's powered from the computer power supply 

Now it's not connected .

I've also unplugd DL connectors on the back of the patch bay one by one just to be sure that the noise it's not coming from audio cables

[Matt Sartori]

Yup it's powered from the computer power supply 

Now it's not connected .

I've also unplugd DL connectors on the back of the patch bay one by one just to be sure that the noise it's not coming from audio cables

any news on this?

Matt Sartori.

[waltzingbear]

if it is still there, turn off all the buckets, just have the center section on, is the tone still there?

[CarloColugnati]

Hello guys, sorry for disappearing !

Ive been far away from the desk for these days .

Will be back working on it tuesday , anyway with all the buckets switched off it still have the noise !