Dc offset pop sound on solo buttons and Console status buttons

[tlmaen]

Hi,
when i press any solo button on my 4ke console, I get an almost fullscales dc sounding pop.
Its really annoying, specially with clients attending.
When one solo button is pressed, pressing another solo doesnt make any additional sound.
Also when i change the status of the console it makes the same loud sound.
Is there anywhere to start looking?
(All of the center section cards are completely recapped).
I figured out that there is a cut bus, but that seems to be a logic thing.
Tried to identify the Pfl/Afl bus in the service manual, but that doesn’t shed any light in to it…

Thanks for your help!
Happy eastern 

[tlmaen]

Tried to narrow down the Problem, so I powered the console with one bucket at a time, but no luck.
Even when all buckets are switched off, it still makes this pop sound.
So I guess its somewhere in the center section…

The VCA Solos doesnt make that sound.
Just the channel solos ant the change of the console status.

Any Ideas where to look?
I find the service manual not very helpful so far…

Thanks,
Tilmann

[tlmaen]

No one any idea...?
Still a big problem and takes away a very important function.

I heard from an old tech guy it might have something to do with grounding.
He remembered all sorts of things when a console is moved to another location...

Thanks,
Tilmann

[Clip6]

Can you zoom/facetime with good tech? Hate to see you still with this problem.

[radardoug2]

There are clues here. First, if adding solos does not give the click, the click relates to when solo is first initiated. Second, its not in a bucket, it is in the main module where solo is controlled. So look at where the solo audio first enters the monitor chain. It would indicate a failed cap, putting dc into the audio chain. You will need the appropriate extender cards for modules in the centre section. You will need at least a scope. Then its faultfinding 101. Study the schematics, and then decide where to start measuring.

[tlmaen]

Can you zoom/facetime with good tech? Hate to see you still with this problem.

You mean if I have a good tech? Or do you have a good tech?

[tlmaen]

There are clues here. First, if adding solos does not give the click, the click relates to when solo is first initiated. Second, its not in a bucket, it is in the main module where solo is controlled. So look at where the solo audio first enters the monitor chain. It would indicate a failed cap, putting dc into the audio chain. You will need the appropriate extender cards for modules in the centre section. You will need at least a scope. Then its faultfinding 101. Study the schematics, and then decide where to start measuring.

Sorry for my late reply, had a ton to record and mix (ITB).
Today is my Tech day.

I figured something out today.
In MIX mode you can hear it only if you press the solo button.
I RECORD mode its actually not the solo button, its the cut button that makes the sound.
Its hard to notice if you only press one, but I managed to press 8 at the same time, than you can hear it.
It is also dependent on the VCA Fader Level (VCAs to Mon pressed). The higher the fader the louder the noise.
If you have 40 faders up its quite loud!
Also each Channel has a different Pop level when you mute it and release it (all Faders at 0).
And: The pope sound is the loudest in RECORD mode, a good few db lower in REPLAY and some other db in MIX mode.
(The small Fader Solo makes a very low click, is the normal? Or should the be dead quiet?)

When I dead patch the pre VCA Ins Ret, switching the Status doesn't make any sound.
So its at least pre VCA...

To remember, it makes the pop sound by switching the status, even when no bucket is powered on, except the CS.
Maybe I have two different problems?

Makes me crazy.
I still try to figure out if its some kind of new wiring/grounding, because this was definitely not Present in My old Studio...

THANKS!

[Clip6]

thatstudioguy on instagram may be able to help.

[Dave Dicson]

We had this problem on a SSL 4K a long time ago. There was a bad run of some of the IC's that were used on the "20" card (very bottom card in the 651 - center section). Another problem is shorted transistors on the "20" card. I've had lots of them. On the "20" card, I added 8 fuses on the data lines to prevent shorted transistors. Never had anymore shorted transistors or blown fuses. Good luck.

[horizonsound]

Yes! The 82E20 card obviously went through a lot of design changes over time. There were many, many revisions to it, and I have seen lots of failures of these cards.
It gave me so much trouble that this was the first card I reverse engineered.

Anthony.

[tlmaen]

Thanks for pointing out the ‘20’ card!
I searched the forum and found some threads about it.
As far as I understand it, it only handles the Group VCAs.
But I have the problem in every individual Channel!
(And as well when I change the Console Status)

Will definitely check the ‘20’ card.
When I bought the console, there was a used spare card in the box, probably damaged…

Thanks!
Tilmann

[Dave Dicson]

I have 3 "20" cards in use and 3 spare cards which I have fixed. I haven't needed one in years, thankfully.

[tlmaen]

Update:

I spend the whole day trying a lot of stuff finding the Problem.
- I disconnected all connections to the ADDAs (pulling EDACs in the Machine Room). No effect.
- I disconnected the complete external Patchbay (56 Tuchel Connectors directly under the Console). No effect.
At this point the console had no connection to the outside world, except for Main Out L/R.
I disconnected these two as well, no effect (You could still see the pop on the compressor, threshold fully clockwise, GR pinning the needle...)
- I disconnected all of the S23E Ribbons on the Fader Cards. That reduced the Pop from 0db Fullscale to -30db, not acceptable.
- Removed the S5E Ribbon from The upper bus cards, Pop Sound was Gone (Obviously, the connection to the Quad Bus).
  With this cable removed, I could switch between the Status with no Pop sound!
- When the QuadPan is activated the pop Sound is a little Bit reduced.

- Then I removed every fckn Channel one by one and pressed Solo to check if the pop sound is gone. No effect at all
- With all channels removed I measured the voltages
  Upper Bus Card was +18,3 (+20) +10,9 (+13) -18,3 (-20)
  On Pin 52 (spare to Channel Logic card CF82E12) I measured +10,9v! Is that correct?
  On Pin 53 (Broadcast Bus) I measured +10,9v! Is that correct? What is the Broadcast Bus?
  On Pin 57 (VCA to Mon Bus) I measured +18v! Is that correct?
  On Pin 58 (Slate Control Bus) I measured +10v! Is that correct?
  On Pin 59 (Ch Solo Cut Bus) I measured +11v! Is that correct?
  On Pin 60 (Status Mix Bus) I measured +10,9v! Is that correct?
  On Pin 61 (Mon Solo Cut Bus) I measured +11v! Is that correct?
  On Pin 62 (Machine Record Bus) I measured +11v! Is that correct?
  On Pin 63 (Status Record Bus) I measured +18v! Is that correct?
  On Pin 64 (Solo disable Bus) I measured +11v! Is that correct?
  On Pin 65 (VCA to Meter Bus) I measured +11v! Is that correct?

Lower Bus Card
  On Pin 1 (QB LF) I measured +20mv! Is that correct?
  On Pin 3 (QB LB) I measured +20mv! Is that correct?
  On Pin 5 (QB RF) I measured +24mv! Is that correct?
  On Pin 7 (QB RF) I measured +44mv! Is that correct?
  On Pin 74 (5v Fader off) I measured 0v! Is that correct?

I checked visually checked all of the QB Cards in the CS and also swapped the between channels (recently recapped), no burnt Rs or Cs
The 82E20 Card looks brand new, no signs of any burned Rs or Blown Cs

I am actually don't know where to look...
I try to narrow the problem down as much as I can before calling a tech. (Hard to find experienced SSL Techs here)

Any new Ideas...?

Thanks!
Tilmann

[horizonsound]

I've had the diodes fail that are part of the SL651 and SL681 solo switches.

If you pull out S17E cable from either under the 651 or the 681, this might identify if one of those two are the issue.

Anthony.

[tlmaen]

Thanks Anthony,
pulling the S17E Cable did not change nor save the Problem.

- Another thing I noticed today, If you press the Ready Group switches it makes the same Pop Sound.
  Some are quiet, some are extra loud...

I will have a tech coming in two weeks.
He Build and serviced the Studio since the mid eighties, and fixed the former 4E and 9J

Grr.

Tilmann